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Vol. XVII No. 7 July 2015 Corporate Office: Plot 99, Sector 44 Institutional Area, Gurgaon -122 003 (HR), Tel : 0124-4951200 e-mail : [email protected] website : www.mtg.in Regd. Office: 406, Taj Apartment, Near Safdarjung Hospital, Ring Road, New Delhi - 110029. Managing Editor : Mahabir Singh Editor : Anil Ahlawat

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Microbes in Human Welfare

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The content for PMT Biology is very vast and does not allow students to engage in inquiry and develop meaningful knowledge. An essential topic for PMT is presented here to enable students grasp the topic, analyse the type of questions appearing in PMTs, and score HIGH.

microbes in human welfare Microbes or microorganisms are those organisms which are not visible to naked eye and can be observed only with the aid of a microscope because they have a size of 0.1 mm or less. Microbes belong to diverse groups of organisms including bacteria, fungi, protozoa, and microscopic plants. Viruses, viroids and prions are also included amongst microbes. Most of the microbes can be grown on nutritive media where they form colonies, e.g., bacteria, fungi. The colonies can be seen with naked eyes. Microbes are ubiquitous in our environment i.e., they are found in the soil, mud, water, air, body of other organisms, food products, clothes, shoes, optical instruments, nails, skin, etc. They may occur even at places where no other organism can possibly exist, e.g., inside thermal vents or geysers with temperature 100°C, under several metres thick snow where temperature is several degrees below 0°C, highly saline or extremely acidic environment, etc. The microorganisms influence man in several ways. Microbes are known to cause various diseases in man and other organisms and for deteriorating food, clothing, furniture, machinery etc. But some of their activities are useful for us. Such activities include antibiotic production, production of dairy products and fermented beverages, sewage treatment etc. Useful activities of microbes can be discussed under several heading as discussed ahead.

microbes in household products In our household we use a variety of microbes or products obtained from them. Curd, cheese, bread etc., which are part of our daily lives, are obtained by microbial activity.

dairy products Dairy products include curd, yoghurt, butter milk, cheese etc. 8

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curd The starter or inoculum used in preparation of milk products containing millions of lactic acid bacteria (LAB) like Lactobacillus are added to skimmed or cream milk at a temperature of about 40°C or less. They convert lactose sugar of milk into lactic acid. Lactic acid causes coagulation of milk protein casein. Milk is changed into curd. Besides the conversion of milk into lactic acid, the LAB also improve its nutritional quality by increasing vitamin B12. Curd is more nutritious than milk as it contains a number of vitamins and organic acids. LAB present in curd also check growth of disease causing microbes in stomach and other parts of digestive tract. Indian curd is used either as such or in other forms such as mattha, chhach or lassi. Yoghurt and butter milk Yoghurt is produced by curdling milk with the help of Streptococcus thermophilus and Lactobacillus bulgaricus. Butter milk is acidulated product which is formed by inoculating skimmed milk with starter culture of Streptococcus cremoris, S. lactis, Lactobacillus acidophilus, Leuconostoc species at 22°C for 18 hours. cheese Cheese is known to be the oldest food item in which microbes are used. There are two groups of cheese, fresh or unripened cheese and ripened cheese. The unripened cheese are made up of milk coagulated by acid or high heat e.g., cottage cheese, while ripened cheese are made through lactic acid bacterial fermentation and coagulated by an enzyme preparation. A large number of microorganisms play a role in the ripening process and different varieties of cheese are obtained depending upon the microorganisms used in production. The CO2 producing culture of Propionibacterium sharmanii is essential for giving swiss cheese its eye or holes, and flavour. Roquefort cheese uses Penicillium roqueforti while camembert cheese employs P.camemberti for ripening. • Soft cheese is ripened by the enzymes from yeast and other fungi that grow on the surface. • Hard cheese is ripened by lactic acid bacteria which grows throughout the cheese, die, autolyse and release hydrolytic

enzymes.

• The semisoft cheese is ripened by proteolytic and lipolytic organisms which soften the curd and give it a flavour.

dough for making food items Numerous food items such as ‘dosa’, ‘idli’, ‘jalebi’ and ‘bread’ are prepared by fermentation process in which one or more kinds of microbes are used. Dosa, uppma and idli are fermented preparation of rice and black gram. The ‘dough’ which is used for making dosa and idli is allowed to ferment overnight for 10 to 12 hours. The bacteria, which come from atmosphere (particularly Leuconostoc mesenteroides, Streptococcus faecalis) cause fermentation so that the dough increases in volume and gets sour. Increase in the volume of dough is due to carbon dioxide gas (CO2) that is released as a result of fermentation. Bread is made from flour obtained by grinding cereal grain usually wheat. Selected strains of Saccharomyces cerevisiae grown on molasses are used as baker’s yeast. A small quantity of yeast is added to wheat flour and kneaded. The kneaded flour is kept at warm temperature for a few hours. It swells up. The phenomenon is called leavening. Leavening is caused by secretion of three types of enzymes by yeast. They are amylase, maltase and zymase. Amylase causes breakdown of a small quantity of starch into maltose sugar. Maltase converts maltose into glucose. Glucose is acted upon by zymase. Zymase is a complex of several enzymes of anaerobic respiration which brings about fermentation. Fermentation of glucose mainly forms ethyl alcohol and carbon dioxide. The two cause swelling or leavening of dough. The leavened dough is baked. Both carbon dioxide and ethyl alcohol evaporate making the bread porous and soft.

single cell proteins A relatively new food source is single cell protein (SCP). Its production began in the late 1960s. The term refers to protein obtained from the large scale growth of microorganisms such as bacteria, yeasts and other fungi, and algae. The protein may be used for human consumption or animal feed. It may also be a useful source of minerals, vitamins, fats and carbohydrates. The common SCP are obtained from Spirulina, yeast and Fusarium graminearum. SCP is rich in high quality protein but poor in fat.

other household products Coconut water is fermented to produce a refreshing drink called toddy. It is a traditional drink in some parts of Southern India. The term toddy is also applied to sweet exudation got by tapping unopened spadix of coconut. Palm sugar or jaggery is produced by 10

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boiling it. The exudation is rich in natural yeasts which bring about its rapid fermentation to produce an intoxicating alcoholic drink. Arrack is obtained by distillation of fermented toddy. If allowed to ferment for more than 24 hours, toddy becomes unpalatable as alcohol is changed to vinegar. Microbes are also used to ferment fish, soyabean and bamboo shoots to make foods. A most popular type of fermented food is produced from soyabeans called tempeh kedele. It is important source of vitamin B12. Tofu and sofu are also obtained from soyabeans.

microbes in industrial products Fermentative activity of microbes is used industrially to obtain a number of products. The two common ones are beverages and antibiotics. The container, where fermentation is carried out, is called fermentor or bioreactor.

Fermented beverages Yeast species used in alcoholic fermentation are Saccharomyces cerevisiae (brewer’s yeast), S. ellipsoidens (wine yeast), S. sake (sake yeast) and S. pireformis (ginger beer/ale yeast). The nutrient medium is barley malt for beer, fermented rye malt for gin, fermented rice for sake, cashew-apple for fenny, potato for vodka, fermented cereals for whisky, fermented molasses for rum and fermented juices for wines and brandy.

baker’s and brewer’s yeasts The yeasts are basically of two types-baker’s yeast and brewer’s yeast. The selected strains of Saccharomyces cerevisiae, used in baking industry to bring about desired changes in flavour and texture of the baked products, are sold as baker’s yeast. They are available in the form of powder or cakes. The yeasts, which are used in the brewing industry for the preparation of alcoholic drinks, are collectively called brewer’s yeast. Different kinds of alcoholic beverages are produced by using different brewer’s yeast and the fermenting medium. Beer and wine are undistilled beverages whereas whisky, rum, gin, brandy, vodka and fenny are distilled beverages. Distilled beverages are called ‘hard liquors’ as they contain higher percentage of alcohol. Beer is an undistilled product of grain-mesh fermentation brought about by Saccharomyces cerevisiae and S. carlsbergensis. Wine is an undistilled product of fruit-juice fermentation brought about by Saccharomyces ellipsoideus. Fermentation can be done using three different methods: (i) Batch culture : In the batch culture, the conditions are set up and not changed from outside once the fermentation starts; for example, no more nutrients are added. This is why the process is described as a closed system. The process is stopped once sufficient product has been formed. The contents of the fermenter are then removed, the product isolated, the microorganism discarded and the fermenter is cleaned and set up for a fresh batch. (ii) Continuous culture : Continuous culture involves continuous long-term operation over many weeks, during which nutrient medium is added as fast as it is used, and the overflow is harvested. Although this is closer to the situation in natural environments, such as the gut, continuous culture has found only limited application. However, it is used for the production of single cell protein where a large biomass of cells is required. (iii) Fed batch culture : This is a compromise between the two systems. With fed-batch culture more control of the process is involved than with batch culture. The period of growth is extended by adding nutrients at low concentrations during the fermentation, and not adding all the nutrients at the beginning. One advantage of this is that the rate of growth can be regulated to keep pace with the rate at which oxygen can be supplied. The process is commonly used to produce yeast cells for the baking industry.

antibiotics The term ‘antibiotics’ was coined by Waksman (1942). Antibiotics (Fr. anti = against; bios = life) are chemical substances secreted by some microorganisms which inhibit the growth and development of other microbes. Antibiotics are obtained from eubacteria, fungi and actinomycetes. Most of them are produced by actinomycetes, specially the genus Streptomyces. The study of antibiotics began by the discovery of penicillin in 1929, when Alexander Fleming proved that the filtrate of a broth culture of Penicillium notatum has antibacterial properties in relation to Gram-positive bacteria. In 1940, Ernest Chain and Howard Florey commercially extracted a relatively stable preparation of penicillin. The chemical was extensively 12

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used in treating wounded American soldiers in world war II. Fleming, Chain and Florey were awarded Nobel Prize in 1945. Waksman and Woodruff isolated actinomycin in 1941 and streptothricin in 1942. Waksman and Albert (1943) and Waksman (1944) discovered streptomycin. Burkholder (1947) isolated chloromycetin. Over 7000 antibiotics are known. Table:

Some common antibiotics, their source and action. Antibiotics

Source

Action

Chloramphenicol

S. venezuelae

Typhoid, whooping cough

Erythromycin

S. erythreus

Diphtheria

Chloromycetin

S. lavendulae

Pneumonia

Streptomycin

S. griseus

Meningitis, Pneumonia, TB

Bacitracin

Bacillus licheniformis

Syphilis, Lymphonema

production of antibiotics Various steps involved in the production of an antibiotic have been summarised in the table given below.

bioactive molecules Cyclosporin - A is an important bioactive chemical produced by the fungus Trichoderma polysporum. It is an 11-membered cyclic oligopeptide. This chemical is used as an immunosuppressive agent in organ transplantation. Statin is produced by yeast Monascus purpureus. It is used as blood cholesterol lowering agent by acting as a competitive inhibitor of enzyme for cholesterol synthesis. Some microbes are used to obtain organic acids, enzymes etc.

organic acids Microbes are also used for commercial and industrial production of certain organic acids. The first organic acid produced through microbial fermentation was lactic acid (Scheele, 1789). Some other common organic acids produced through microbial activity are acetic acid, citric acid and butyric acid. There are mainly two steps in acetic acid or vinegar production. In the first stage yeast converts sugar into ethanol anaerobically while in the second step ethanol is oxidised to acetic acid aerobically by Acetobacter aceti. This process is called acetification. This organic acid is employed in pharmaceuticals, colouring agents, insecticides, plastics, etc. Citric acid is obtained through the fermentation carried out by Aspergillus niger and Mucor species on sugary syrups. Yeast can also be employed, provided its nutrient medium is made deficient of iron and manganese. Citric acid is employed in dyeing, engraving, medicines, inks, flavouring and preservation of food and candies. Lactic acid fermentation is carried out by both bacteria (e.g., Streptococcus lactis, Lactobacillus species) and fungi (e.g., Rhizopus). Clostridium acetobutylicum is the bacteria that is used for production of butyric acid.

enzymes Enzymes are proteinaceous substances of biological origin which are capable of catalysing biochemical reactions without themselves undergoing any change. Streptokinase (Tissue Plasminogen Activator or TPA) is an enzyme obtained from the cultures of some haemolytic streptococci. It has fibrinolytic effect. Therefore, it helps in clearing blood clots inside the blood vessels through dissolution of intravascular fibrin. Pectinases are obtained commercially from Byssochlamys fulva. Along with proteases, they are used in clearing of fruit juices. Other uses are in retting of fibres and preparation of green coffee. Lipases are lipid dissolving enzymes that are obtained from Candida lipolytica and Geotrichum candidum. Lipases are added in detergents for removing oily stains from laundry. They are also used in flavouring cheese.

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microbes in sewage treatment Sewage is waste water having food residues, animal and human excreta, detergents, discharges from commercial and industrial establishments and pathogenic microbes etc. Sewage poses many harmful effects such as: – It results in dissemination of water-borne diseases caused by microorganisms. – It may cause depletion of dissolved oxygen in water. Reduction in oxygen availability may kill aerobic aquatic organisms. – Untreated sewage produces offensive odour. Thus sewage treatment is essential for reducing harms done by it. Whenever untreated sewage is disposed into natural waters such as streams, ponds, lakes, etc., the normal amount of dissolved oxygen present in water, gets quickly utilised by microorganisms as a result of oxidation of organic matter present in sewage. Biochemical oxygen demand (BOD) is increased. BOD represents the amount of dissolved oxygen that would be consumed if all the organic matter in one litre of water were oxidised by microorganism (at 20°C). It is an indicator of water quality. Thus, high value of Biochemical Oxygen Demand (BOD) means the water is highly polluted by organic matter. Low value of BOD means the water is either normal or less polluted by organic matter. Sewage water can be purified by passing it through sewage treatment plants with the action of heterotrophic microorganisms. A sewage treatment plant separates solids from liquids by physical processes and purifies the liquid by biological processes. There are two stages of this treatment; primary or physical treatment and secondary or biological treatment.

primary treatment It removes floating and suspended solids from sewage through two processes: filtration and sedimentation. First, floating matter is removed through sequential filtration with small pore filter progressively. The filtrate is kept in large open settling tanks where grit (sand, silt, small pebbles) settles down. The sediment is called primary sludge while the supernatant is called effluent. The primary sludge traps a lot of microbes and debris. It is subjected to composting or land fill where anaerobic digestion removes the organic matter.

secondary treatment There are several methods of secondary treatment, e.g., oxidation tanks, trickling filter, and activated sludge system. In activated sludge system, the primary effluent is taken to aeration tanks. A large number of aerobic heterotrophic microbes grow in the aeration tank. They form flocs. Flocs are masses of bacteria held together by slime and fungal filaments to form mesh like structures. The microbes digest a lot of organic matter, converting it into microbial biomass and releasing a lot of minerals. As the BOD of the waste matter is reduced to 10-15% of raw sewage, it is passed into settling tank. Thus secondary treatment is more or less biological. The sediment of settling tank is called activated sludge. A part of it is used as inoculum in aeration tank. The remaining is passed into a large tank called anaerobic sludge digester. Anaerobic microbes digest the organic mass as well as aerobic microbes of the sludge. They are of two types, nonmethanogenic and methanogenic. Methanogenic bacteria produce a mixture of gases containing methane, H2S and CO2. The mixture called biogas is inflammable and is a source of energy. The spent sludge can be used as manure or part of compost. Finally the treated sewage effluent is subjected to chemical treatment for disinfection before releasing it into natural water bodies like rivers and streams.

river action plan Before 1985 very few cities and towns had sewage treatment plants. The municipal waste water was discharged directly into rivers resulting in their pollution and high incidence of water borne diseases. In order to protect the major rivers of India from sewage pollution, the Ministry of Environment and Forests, has initiated development of sewage treatment plants under the National River Conservation Authority, e.g., Ganga Action Plan (GAP), Yamuna Action Plan, Sutlej Action Plan, Gomti Action Plan etc. 14

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microbes in production oF biogas Biogas is a methane rich fuel gas produced by anaerobic breakdown or digestion of biomass with the help of methanogenic bacteria or methanogens Methanobacterium is a common methanogenic bacteria. Biogas is made up of methane (50-70%), carbon dioxide (30-40%) with traces of nitrogen, hydrogen sulphide and hydrogen. 50% of the combustible energy present in the organic waste can be changed into methane gas. The energy released from biogas depends upon the proportion of methane present in it. The calorific value of biogas is 23-28 MJ/m3. As the biogas production is an anaerobic process, it is carried out in an air tight, closed cylindrical concrete tank called a digester. The tank has a concrete inlet basin on one side for feeding fresh cattle dung. There is a concrete outlet on the outer side for removing the digested sludge. The top of the tank serves as the gas tank. It has an outlet pipe for the biogas. Biogas generation is a three-stage anaerobic digestion of animal and other organic wastes. The latter consist of lignin, cellulose, hemicellulose, lipids and proteins. Lignin cannot be broken down under anaerobic conditions. Cellulose digestion is slower than that of other substances. In the first stage of anaerobic digestion (solubilisation), facultative anaerobic decomposer microbes bring about enzymatic breakdown of complex organic compounds into simpler and soluble compounds often called ‘monomers’. For this, the decomposer microbes secrete cellulases, proteases and lipases (cellulolytic, proteolytic and lipolytic enzymes). In the second stage (acidogenesis), the simple soluble compounds of microbial digestion or monomers are acted upon by fermentation causing microbes. The latter change the monomers into organic acids. Organic acids, especially acetic acid, are acted upon by methanogenic bacteria in the third or final stage (methanogenesis). The methane bacteria convert organic acids as well as carbon dioxide into methane. The biogas thus formed is stored in tanks for supply. The technology of biogas production was developed in India by collaboration of Indian Agriculture Research Institute (IARI) and Khadi and Village Industries Commission (KVIC).

advantages of biogas Using organic wastes first for biogas generation has following advantages over their direct use as fuel or fertiliser: (i) It provides both energy and manure. (ii) Biogas has wider applications than the direct burning of organic wastes. (iii) The energy value of biogas is lower than that of organic matter but due to more efficient handling, the net energy output is roughly equal to the output in direct burning of organic wastes. (iv) Minimises the chances of spread of faecal pathogens. (v) The fertiliser value of the manure produced in biogas plants is similar to that of manure formed directly from organic wastes. (vi) Biogas use does not add to pollution.

microbes as biocontrol agents The natural method of pest and pathogen control involving use of viruses, bacteria and other insects (which are their natural predators and pests) is called biocontrol or biological control. For example, Lady bird beetle (beetle with red and black markings) feeds on aphids while dragonflies prey upon mosquitoes. Free living fungus Trichoderma exerts biocontrol over several plant pathogens. An example of microbial biocontrol agent that can be introduced in order to control butterfly caterpillars is the bacteria Bacillus MT BIOLOGY

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thuringiensis. These are available in sachets as dried spores. Spores of this bacterium contain insecticidal cry protein. These spores which are mixed with water and sprayed onto vulnerable plants such as Brassica and fruit trees, where these are eaten by the insect larvae. In the gut of the larvae, the toxin is released and the larvae get killed. The bacterial disease will kill the caterpillars, but leave other insects unharmed. Because of the development of methods of genetic engineering in the last decade or so, the scientists have introduced B. thuringiensis toxin genes into plants. Such plants are resistant to attack by insect pests. Bt-cotton is one such example, which is being cultivated in some states of our country. Baculoviruses are pathogens that attack insect pests and other arthropods. The majority of baculoviruses used as biological control agents belong to the genus Nucleopolyhedrovirus. These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications. They have been shown to have no negative impacts on plants, mammals, birds, fish or even on non-target insects. This is especially desirable when beneficial insects are being conserved to aid in an overall integrated pest management (IPM) programme, or when an ecologically sensitive area is being treated. • • • • • •

some other biocontrol agents Phytophthora palmivora - Controls growth of milkweed vine Cercospora rodmanii - Controls growth of Eichhornia crassipes Praying Mantis - Successful in combating scale insect Beauveria bassiana - Successfully employed in controlling potato beetle Rodolia cardinalis - Controls cottony cushion scale (Icerya purchasi) Cyrtorhinus mundulus - Controls sugarcane leaf hopper.

microbes as bioFertilisers Chemical fertilisers are being used in increasing amounts in order to increase output in high yielding varieties of crop plants. However, chemical fertilisers cause pollution of water bodies as well as ground water, besides getting stored in crop plants. Therefore, environmentalists are pressing for switch over to organic farming. Organic farming is the raising of unpolluted crops through the use of manures, biofertilisers and biocontrol agents that provide optimum nutrients to crop plants, keeping pests and pathogens under control. Biofertilisers are organisms which bring about nutrient enrichment of the soil by enhancing the availability of nutrients like nitrogen and phosphorus to the crops. Some of the important biofertilisers recommended for the use in agriculture are discussed ahead.

microphos biofertilisers They release phosphate from bound and insoluble states, e.g., Bacillus polymyxa, Pseudomonas striata, Aspergillus species.

Free living nitrogen fixing bacteria Free-living nitrogen fixing bacteria fix atmospheric nitrogen in the soil and make it available for the higher plants. The best example is Azotobacter. Apart from Azotobacter, some other genera of free living soil enhabiting bacteria such as Clostridium, Bacillus polymyxa, Beijerinckia, Klebsiella, Derxia and Rhodospirillum are also known to fix atmospheric nitrogen. Inoculation of soil with these bacteria helps in increasing yield and saving of nitrogen fertilisers. For example, Azotobacter occurring in fields of cotton, maize, jowar and rice, not only increase yield but also saves nitrogen fertiliser to the tune of 10–25 kg/ha. Its inoculation is available under the trade name of azotobactrin.

symbiotic nitrogen fixing bacteria They form a mutually beneficial association with the plants. The most important of the symbiotic nitrogen fixing bacteria is Rhizobium. The bacteria Rhizobium occurs freely in the soil but fails to fix nitrogen in the free state. It multiplies as soon as it gets to rhizosphere of leguminous plants, enters into their roots and forms specialised structures called root nodules. The bacteria fix atmospheric nitrogen only in the root nodules and that too when present in the bacteroid forms. The genus Rhizobium includes many species and each species further includes many strains. It has been observed that a specific strain of Rhizobium sp. gets symbiotically associated with specific species of leguminous plant, e.g., Rhizobium leguminosarum (in pea), R. meliloti (in alfalfa), R. trifolii (in clover), R. phaseoli (in beans), R. lupini (in lupines) and R. japonicum (in soybeans), etc. Therefore, it is important to apply specific strain of Rhizobium to a particular leguminous crop in order to get maximum advantage.Frankia, a nitrogen fixing mycelial bacterium (actinomycete), is associated symbiotically with the root nodules of several nonlegume plants like Casuarina, Alnus (alder) Myrica, Rubus, etc. 16

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loose association of nitrogen fixing bacteria Certain nitrogen fixing bacteria like Azospirillum live around the roots of higher plants without developing any intimate relationship. It is often called rhizosphere association. The bacteria obtain some plant exudate and use the same as part of their food requirement. The bacteria fix nitrogen and exude a part of the fixed nitrogen for use by the plant. The phenomenon is termed as associative mutualism or associative symbiosis.

Free living nitrogen fixing cyanobacteria A number of free living cyanobacteria or blue-green algae have the property of nitrogen fixation, e.g., Anabaena, Nostoc, Aulosira, Totypothrix, Cylindrospermum, Stigonema. Aulosira fertilissima is considered to be the most active nitrogen fixer of rice fields in India (Aiyer et al, 1972). Cylindrospermum licheniforme grows in sugarcane and maize fields. Cyanobacteria are extremely low cost biofertilisers.

symbiotic nitrogen fixing cyanobacteria Nitrogen fixing cyanobacteria (blue-green algae) form symbiotic association with several plants, e.g., cycad roots, lichens, liverworts, Azolla (fern). Azolla-Anabaena association is of great importance to agriculture. Anabaena azollae resides in the leaf cavities of the fern Azolla where it fixes nitrogen.

mycorrhiza It is a mutually beneficial or symbiotic association of a fungus with the root of a higher plant. The most common fungal partners of mycorrhiza are Glomus species. Depending upon the residence of the fungus, mycorrhizae are of two types– ectomycorrhiza and endomycorrhiza. In ectomycorrhiza the fungal mycelium completely encloses the feeder rootlets forming sheath or mantle. The hyphae penetrate the intercellular spaces of the root cortex to form a network, called the ‘Hartig net’. The mantle of fungal hyphae increases the absorptive surface of roots and hence serve better intake of nutrients such as nitrogen, phosphorus, calcium and potassium from the surrounding soil. Ectomycorrhizae are known to occur in several genera such as Pinus, Quercus, Betula, Alnus, Salix, Populus etc. In endomycorrhiza fungus does not form an external sheath of mantle. The fungus mostly lives in the intercellular spaces as well as intracellularly in the cortical cells of roots. Only a small portion of fungus lives outside the root. Such type of mycorrhizal association occurs in the roots of grasses, cereals, legumes, rubber, tea, tobacco, soybean, citrus and in many orchids (Neottia, Vanilla, Galeola, Epipogon, etc.). One of the important type of endomycorrhizae is vesicular-arbuscular mycorrhizae (VAM). In this association, the fungal mycelium forms some special kinds of organs, called vesicles and arbuscules, within the root cortical cells. They serve as the food storage organs of the fungus. Endomycorrhizae stimulate the absorption of phosphorus, zinc, copper, sulphur, potassium and various other elements by roots. They secrete antimicrobial substances to protect the plants from pathogen attack.

importance of biofertilisers (i) They increase the yield of plants by 15–35%. (iii) Farmers can prepare the inoculum themselves. (v) Biofertilisers do not allow pathogens to flourish.

(ii) Biofertilisers are effective even under semi-arid conditions. (iv) They improve soil texture. (vi) They produce vitamins and growth promoting biochemicals.

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New MCQs 1. The inoculum is added to the fresh milk in order to convert milk into curd, the term ‘inoculum’ here refers to (a) a starter rich in vitamin B12 (b) a starter rich in proteins (c) a starter containing millions of LAB (d) an aerobic digester. 2. Living organisms used to enrich the nutrient quality of the soil are called as (a) biocontrol agents (b) biofertilisers (c) synthetic fertilisers (d) natural fertilisers. 3. Which of the following beneficial bacteria is also present in the rumen of cattle? (a) Azotobacter (b) Rhizobium (c) Methanobacterium (d) Azospirillum 4. Which of the following is the biocontrol agent for cottony cushion scale (Icerya purchasi)? (a) Cyrtorhinus mundulus (b) Rodolia cardinalis (c) Beauveria bassiana (d) Phytophthora palmivora 5. During the primary treatment of sewage, solid particles that settle down are called (a) flocs (b) primary sludge (c) activated sludge (d) anaerobic sludge. 6. Members of which of the following microbial groups do not have much beneficial value? (a) Fungi (b) Prions (c) Bacteria (d) Protozoa 7. Which of the following statements is incorrect? (a) Word antibiotic is a misnomer. Anti is a Greek word that means ‘against’, and bio means ‘life’, together they mean ‘against life’ (in the context of disease causing organisms); whereas with reference to human beings, they are ‘pro life’ and not against. (b) Flocs are masses of bacteria with interwoven fungal filaments which form mesh like structures. (c) Components of biogas are methane (50 – 70%), carbon dioxide (30 – 40%) and traces of hydrogen, nitrogen and H2S. (d) None of these 8. A cholesterol lowering agent is obtained from (a) Aspergillus niger (b) Trichoderma polysporum (c) Pencillium notatum (d) Monascus purpureus 18

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9. _____ is the first step of sewage treatment. (a) Precipitation (b) Chlorination (c) Sedimentation (d) Aeration 10. Which of the following statements is correct with regard to biocontrol agents? (a) Ladybird beetles and dragonflies are used to get rid of aphids and mosquitoes. (b) Bacillus thuringiensis bacteria are used to control butterfly caterpillars. (c) Trichoderma species are used to control several plant pathogens. (d) All of these 11. Fumagillin is a (i) antibiotic obtained from (ii) and is effective against (iii) . (a) (i) broad spectrum (ii) Aspergillus fumigatus (iii) Salmonella (b) (i) specific (ii) Penicillium griseofulvum (iii) spirochaetes (c) (i) broad spectrum (ii) Gliocladium virens (iii) Shigella (d) (i) Specific (ii) Streptomyces venezuelae (iii) Pseudomonas 12. Which of the following are the characteristics of a good antibiotic? (a) Harmless to host with no side effect (b) Ability to destroy all strains of pathogen (c) Quick action (d) All of these 13. Rancidity of butter is due to (a) gluconic acid (b) citric acid (c) butyric acid (d) lactic acid. 14. Leavening of kneaded flour mixed with yeast is caused by enzyme (a) amylase (b) maltase (c) zymase (d) all of these. 15. Toddy is a traditional drink of some parts of South India which is obtained by (a) unopened spadices of coconut (b) soyabean and wheat (c) tender bamboo shoots (d) rice and black gram.

(a) A-q; B-s; C-t; D-r (c) A-r; B-s; C-q; D-t

Exam Section 1. Viruses of the genus Nucleopolyhedrovirus are employed as (a) gobar gas producers (b) biological control agents (c) anaerobic sludge digesters (d) antibiotics (e) atmospheric nitrogen fixing agents. (Kerala PMT 2014) 2. Select the correct pair of microorganism and the product obtained from it. (a) Monascus purpureus - produces large holes in Swiss cheese. (b) Saccharomyces cerevisiae - used for making wine and beer after distillation. (c) Streptococcus - produces streptokinase which is used to remove clots. (d) Aspergillus niger - produces citric acid and butyric acid. (AIIMS 2014)

3. Wine and beer are produced directly by fermentation whereas brandy and whisky require both fermentation and distillation. This is because (a) fermentation is inhibited at an alcohol level of 10-18% (b) distillation prolongs storage (c) distillation improves quality (d) distillation purifies the beverage. (AIIMS 2014)

(b) A-r; B-s; C-q; D-p (d) A-t; B-q; C-s; D-r (Karnataka CET 2014)

8. Microorganism used for commercial production of acetic acid is (a) Saccharomyces cerevisiae (b) Aspergillus niger (c) Acetobacter (d) Clostridium butylicum. (J & K 2014)

9. Which of the following microbes is correctly matched with its function? (a) Aspergillus niger – Production of lactic acid (b) Trichoderma – Lowers blood cholesterol polysporum (c) Saccharomyces – Production of citric acid cerevisiae (d) Methanogenic – Gobar gas formation bacteria (AIIMS 2014) 10. Microbe used for biocontrol of pest butterfly caterpillars is (a) Saccharomyces cerevisiae (b) Bacillus thuringiensis (c) Streptococcus sp. (d) Trichoderma sp. (NEET - Karnataka 2013)

6. ‘Roquefort cheese’ is ripened by using a (a) bacterium (b) type of yeast (c) cyanobacteria (d) fungus. (Karnataka CET 2014)

11. Which one of the following microbes forms symbiotic association with plants and helps them in their nutrition? (a) Azotobacter (b) Aspergillus (c) Glomus (d) Trichoderma (AIPMT Prelims 2012) 12. A nitrogen-fixing microbe associated with Azolla in rice fields is (a) Spirulina (b) Anabaena (c) Frankia (d) Tolypothrix. (AIPMT Prelims 2012) 13. Which one of the following is an example of carrying out biological control of pests/diseases using microbes? (a) Trichoderma sp. against certain plant pathogens. (b) Nucleopolyhedrovirus against white rust in Brassica. (c) Bt-cotton to increase cotton yield. (d) Lady bird beetle against aphids in mustard. (AIPMT Prelims 2012)

7. Match the microbial products listed under Column I with the related microbes given under Column II. Choose the appropriate option from the given choices. Column I Column II A. Citric acid p. Methanobacterium B. Cyclosporin A q. Monascus purpureus C. Statin r. Aspergillus niger D. Gobar gas s. Trichoderma polysporum t. Clostridium butylicum

14. Match the items in Column I with those in Column II and select the correct answer from the codes given below. Column I Column II P. Blue green algae as (i) Ectomycorrhiza biofertilisers Q. Fungi as biofertilisers (ii) Thiobacillus sp. R. Free living nitrogen (iii) Anabaena sp. fixing bacteria S. Phosphate solubilising (iv) Clostridium sp. bacteria

4. Yeast is used for commercial production of (a) methanol (b) ethanol (c) butanol (d) citric acid.

(AMU 2014)

5. Statin, a blood-cholesterol lowering agent, is commercially obtained from (a) Trichoderma polysporum (b) Acetobacter aceti (c) Clostridium butylicum (d) Monascus purpureus. (AMU 2014)

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(a) (b) (c) (d)

P-(iii), Q-(i), R-(iv), S-(ii) P-(iii), Q-(i), R-(ii), S-(iv) P-(iii), Q-(iv), R-(i), S-(ii) P-(iv), Q-(ii), R-(i), S-(ii) (WB JEE 2012)

15. Free living bacteria that can fix N2 from soil is (a) Clostridium (b) Azotobacter (c) Beijerinckia (d) all of these. (Odisha 2012) 16. Due to which of the following organisms, yield of rice is increased? (a) Sesbania (b) Bacillus popilliae (c) Anabaena (d) Bacillus subtilis (CBSE 1999; BHU 2012) 17. Which one of the following is not a biofertiliser? (a) Agrobacterium (b) Rhizobium (c) Nostoc (d) Mycorrhiza (AIPMT Prelims 2011) 18. An organism used as a biofertiliser for raising soyabean crop is (a) Azotobacter (b) Azospirillum (c) Rhizobium (d) Nostoc. (AIPMT Prelims 2011) 19. Which one of the following is not used in organic farming? (a) Glomus (b) Earthworm (c) Oscillatoria (d) Snail. (AIPMT Prelims 2011) 20. Consider the following statements (A–D) about organic farming. (A) Utilises genetically modified crops like Bt cotton. (B) Uses only naturally produced inputs like compost. (C) Does not use pesticides and urea. (D) Produces vegetables rich in vitamins and minerals. Which of the above statements are correct? (a) B, C and D (b) C and D only (c) B and C only (d) A and B only (AIPMT Mains 2011) 21. Select the correct statement. (a) Acetobacter aceti produces citric acid. (b) Saccharomyces cerevisiae is used as clot buster. (c) Penicillium notatum restricts the growth of Staphylococci. (d) Methanogens are found in aerobic conditions. (AIIMS 2011) 22. Biogas produced by fermentation of manure, sewage, cattle dung, etc., predominantly comprises (a) methane, nitrogen and hydrogen (b) methane and carbon dioxide (c) methane and carbon monoxide (d) methane and nitric oxide. (DUMET 2011) 20

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23. Trichoderma species are potentially useful as (a) biopesticides (b) biofertilisers (c) methanogens (d) vectors for genetic engineering. (DUMET 2011) 24. Biogas production is carried out by (a) thermoacidophiles (b) methanogens (c) halophiles (d) ruminants. (AFMC 2011) 25. Which one of the following is a bacterial biofertiliser? (a) Anabaena (b) Nostoc (c) Rhizobium (d) Oscillatoria (J & K 2011) 26. Which of the following is not used as a biopesticide? (a) Trichoderma harzianum (b) Nuclepolyhedrovirus (c) Xanthomonas campestris (d) Bacillus thuringiensis (CBSE 2009) 27. Which is not a biofertiliser? (a) Rhizobium leguminosarum (b) Anabaena (c) Bacillus thuringiensis (d) Nostoc

(DPMT 2008)

28. An insecticide extracted from the leaves of neem is (a) aldicarb (b) malathion (c) rotenone (d) azadirachtin. (UP-CPMT 2008) 29. Most potential organism for the production of insecticide is (a) Xanthomonas oryzae (b) Bacillus thuringiensis (c) Erannis tiliaria (d) Heliothis zea (Odisha 2007) 30. Which of the following is free living aerobic and nonphotosynthetic nitrogen fixing bacterium ? (a) Azotobacter (b) Rhizobium (c) Anabaena (d) Clostridium (J & K 2004, 2005)

Assertion & Reason The following questions consist of two statements each : assertion (A) and reason (R). To answer these questions, mark the correct alternative as directed below : (a) If both A and R are true and R is the correct explanation of A. (b) If both A and R are true but R is not the correct explanation of A. (c) If A is true but R is false. (d) If both A and R are false. 1. Assertion : Curd is more nutritious than milk as it contains a number of organic acids and vitamin B12. Reason : LAB present in curd check growth of disease causing microbes in stomach.

2. Assertion : Pathogens often develop resistance to existing antibiotics.

Reason : The resistance is generally produced due to extrachromosomal genes present in plasmids.

3. Assertion : Citric acid was the first organic acid to be produced from the microbial fermentation in starchy and sugary medium. Reason : Rancidity of butter is due to formation of citric acid.

4. Assertion : Rennet is an extract from the stomach of calf that contains enzyme rennin. Reason : Rennet is added in detergents for removing oily stains from laundry.

5. Assertion : A high Biochemical Oxygen Demand (BOD) indicates the presence of large number of microorganisms in a water body which suggests a high level of pollution. Reason : BOD is the amout of oxygen taken up by microorganisms that decompose organic waste matter in water.

6. Assertion : The excreta of cattle is used for the generation of biogas, commonly called gobar gas. Reason : Methanogens, which grow aerobically on cellulose material help in the production of gobar gas.

7. Assertion : Nucleopolyhedrovirus has been shown to have no negative impacts on plants, mammals, birds, fish or even on non-target insects. Reason : Nucleopolyhedrovirus is excellent genus for species specific narrow spectrum insecticidal applications.

Short Answer Type Questions 1. Milk starts to coagulate when lactic acid bacteria (LAB) is added to warm milk as a starter. Mention any other two benefits LAB provides. 2. What does “leg” in leghaemoglobin refer to? Why is this pigment called oxygen-scavenger? 3. Explain various methods used for carrying out fermentation process. 4. Describe the steps involved in the production of an antibiotic. 5. (i) How is activated sludge produced during sewage treatment? (ii) Explain how this sludge is used in biogas production. 6. Compare biocontrol agents and biofertilisers. 7. Explain the scientific reason for growing Azolla pinnata in the rice field. .

Answer

Key

New MCQs 1. (c) 6. (b) 11. (a)

2. (b) 7. (d) 12. (d)

3. (c) 8. (d) 13. (c)

4. (b) 9. (c) 14. (d)

5. (b) 10. (d) 15. (a)

Exam Section 1. 6. 11. 16. 21. 26.

(b) (d) (c) (c)

(c) (c)

2. 7. 12. 17. 22. 27.

(c) (b)

(b) (a) (b) (c)

3. 8. 13. 18. 23. 28.

(d) (c)

(a) (c) (a) (d)

4. 9. 14. 19. 24. 29.

4.

(d) (b)

(a) (d) (b) (b)

5. 10. 15. 20. 25. 30.

(c)

5.

(a)

(b) (d)

(d) (c) (c) (a)

Assertion & Reason 1. 6.

(b) (c)

2. 7.

(b) (a)

3.

(d)

Short Answer Type Questions 1. Two benefits provided by LAB are : (i) It increases nutritional quality of curd by increasing vitamin B12 content. (ii) It checks the growth of disease-causing organisms in the gut. 2. The ‘leg’ in leghaemoglobin refers to leguminous plants. The leghaemoglobin is referred to as oxygen scavanger because it combines rapidly with O2 to avoid any inhibitory effect of oxygen on the enzyme nitrogenase. 3. Fermentation can be done using three different methods: (i) Batch culture : In the batch culture, the conditions are set up and not changed from outside once the fermentation starts; for example, no more nutrients are added. This is why the process is described as a closed system. The process is stopped once sufficient product has been formed. The contents of the fermenter are then removed, the product isolated, the microorganism discarded and the fermenter is cleaned and set up for a fresh batch. (ii) Continuous culture : Continuous culture involves

continuous long-term operation over many weeks, during which nutrient medium is added as fast as it is used, and the overflow is harvested. Although this is closer to the situation in natural environments, such as the gut, continuous culture has found only limited application. However, it is used for the production of single cell protein where a large biomass of cells is required. (iii) Fed-batch culture : This is a compromise between the two systems. With fed-batch culture more control of the process is involved than with batch culture. The period of growth is extended by adding nutrients at low concentrations during the fermentation, and not adding all the nutrients at the beginning. One advantage of this is that the rate of growth can be regulated to keep pace with the rate at which oxygen can be supplied. The process is commonly used to produce yeast cells for the baking industry. MT BIOLOGY

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4. Various steps involved in the production of an antibiotic are as follows:

5. (i) A large number of aerobic heterotrophic microbes grow in the aeration tank. They include bacteria, some filamentous fungi, yeast and protozoans. These aerobes grow in “flocs” and consume a major part of organic matter so that the BOD of sewage is reduced. Now the effluent is passed through a sedimentation tank where microbial flocs are allowed to settle down. The settled materials is called ‘activated sludge’. (ii) A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters. The aerobic microbes in the sludge get killed. The anaerobic bacteria digest the organic

mass including dead bacteria and fungi in the sludge and produce mixture of gases like methane, hydrogen sulphide and CO2 which constitute biogas. The left out sludge is used as manure. 6. The natural method of pest and pathogen control involving use of viruses, bacteria and other insects (which are their natural predators and pests) is called biocontrol or biological control. For example, Lady bird beetle (beetle with red and black markings) feeds on aphids while dragonflies prey upon mosquitoes. Free living fungus Trichoderma exerts biocontrol over several plant pathogens. An example of microbial biocontrol agents that can be introduced in order to control butterfly caterpillars is the bacteria Bacillus thuringiensis. Biofertilisers are the microorganisms such as bacteria, cyanobacteria, fungi etc., which bring about soil nutrient enrichment, maximise the ecological benefits and minimise the environmental hazards. 7. Azolla pinnata is a free floating fresh water fern which multiplies rapidly, doubling every 5–7 days. The fern can coexist with rice plants because it does not interfere with their growth. A symbiotic blue green algae, Anabaena azollae resides in the leaf cavities of the fern. It fixes nitrogen. A part of the fixed nitrogen is excreted in the cavities and becomes available to the fern. The decaying fern plants release the same for utilisation of the rice plants. When field is dried at the time of harvesting, the fern functions as the green manure, decomposing and enriching the field for the next crop. 

U N S C R A MB L E

ME

Unscramble the given words using the references given below. Scrambled letters 1. 2. 3. 4. 5.

POIETEP VSAINONI IRPOAMRACOPIOGTN GNYOLSYECO BVNILFIORA

6. TCIFOIRNBITOIAFO 7. YHRONTAKORE 8. PECLTSOUAL 9. INCTNLAOIC 10. ESRKAPTSIOTEN

Clues Antigenic determinant. A stage of ecological succession. Helps in rapid multiplication of plants. An ecological study at community level. Also called yellow enzyme and its deficiency causes cheilosis. Plant breeding for improved food quality. Male birth. Plant cell organelle which stores substances like starch, fat and proteins. Peptide hormone that acts opposite to parathyroid hormone in Ca2+ metabolism. Helps in clearing blood clots inside the blood vessels.

Words ........................................... ........................................... ........................................... ........................................... ........................................... ........................................... ........................................... ........................................... ........................................... ...........................................

Readers can send their answer with complete address by 10th of every month to win exciting prizes. Winners’ name with their valuable feedback will be published in next issue. 22

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BOGGLERS

 If you have a bone marrow transplant, your blood can have the donor’s DNA and your salival and hair DNA will be your own. It has caused people to be wrongly arrested based on DNA evidence.  If you could type 60 words per minute, eight hours a day, it would take approximately 50 years to type the human genome.  If you were to lay out all the arteries, capillaries and veins in one adult, end-to-end, they would stretch about 60,000 miles (100,000 kilometers). Even more interesting is that, the capillaries, which are the smallest of the blood vessels, make up about 80 percent of this length. By comparison, the circumference of the Earth is about 25,000 miles (40,000 km). That means a person’s blood vessels could wrap around the planet approximately 2.5 times.  Across the animal kingdom, heart rate is inversely related to body size. In general, the bigger the animal, the slower is its resting heart rate. A blue whale’s heart is about the size of a compact car, and beats only five times per minute. A shrew, on the other hand, has a heart rate of about 1,000 beats per minute.  The average strawberry has 200 seeds. It’s the only fruit that bears its seeds on the outside.  Honey bee is the only insect that produces food eaten by man. Honey is the only insect created food with therapeutic, medicinal, nutritional and cosmetic value.  The honey bee’s wings stroke incredibly fast, about 200 beats per second, thus making their famous, distinctive buzz. A honey bee can fly for upto six miles, and as fast as 15 miles per hour.  While awake, your brain generates between 10 and 23 watts of power or enough energy to power a light bulb.  Much like fingerprints, everyone also has a unique tongue print.  The acid in your stomach is so powerful that it can dissolve razor blades.  It is impossible to tickle yourself. Actually two brain regions are involved in the processing how tickling feels. The somatosensory cortex processes touch and the anterior cingulate cortex processes pleasant information. Both these regions are less active during self-tickling as compared to tickling performed by someone else.  The earth has more than 80,000 species of edible plants.  Pomology is the branch of horticulture that is concerned with study and cultivation of fruits.  The world’s most popular fruit is the tomato. Tomatoes have more genes than humans.  Fallopian tube is no wider than the head of a pin.  The female human body is capable of giving birth to 35 children in one lifetime.  The human reproductive system contains the largest and smallest cells. Sperm cell is smallest (5 mm × 3 mm in size) and female’s ovum is the largest human cell (about 120 mm is diameter).  There is a positive correlation between vitamin D and testosterone levels in men. The more sunlight exposure a man gets the more likely it is that he has elevated testosterone levels.  Cuddling helps to heal physical wounds faster due to the release of oxytocin, which is proven to reduce swelling.  Laughter is usually the best natural medicine for stress. It lowers levels of cortisol, adrenaline, etc., which are stress aggravating hormones; and it releases feel-good hormones, such as endorphins.  While sitting at your desk, make clockwise circles with your right foot, while doing this, draw the number “6” in the air with your right hand. Your foot will change the direction.  Intelligent people have more zinc and copper in their hair.  The surface area of human lung is equal to tennis court.  Human nose can detect 50,000 different scents.  The HIV-genome, which is about 10,000 nucleotides long, can exist as 106020 different sequences. To compare there are 1011 stars in the Milkyway galaxy and 1080 protons in the universe.  Coral reefs are the most diversified of all ecosystems on Earth.  Madagascar is an example of biodiversity hotspot because almost all of its living organisms cannot survive anywhere else on Earth. 

MH-CET Maharashtra Common Entrance Test

1. In the first step of monohybrid cross experiment, Mendel selected pea plants which were (a) pure tall as male and pure dwarf as female (b) pure tall as female and pure dwarf as male (c) heterozygous tall as male and pure dwarf as female (d) heterozygous tall as female and pure dwarf as male. 2. In Griffith’s experiment, the conversion of R-type to S-type of Diplococcus pneumoniae when mixed with heat killed S-type is called (a) mutation (b) transduction (c) transfection (d) transformation. 3. Semi-dwarf rice variety IR-8 was developed in (a) Taiwan (b) Philippines (c) India (d) China. 4. Which one of the following is a non-endospermic seed? (a) Sunflower (b) Coconut (c) Groundnut (d) Wheat 5. Which one of the following is not a mycoherbicide? (a) Phytophthora palmivora (b) Xanthomonas sp. (c) Alternaria crassa (d) Fusarium sp. 6. During anaerobic respiration the conversion of pyruvate into acetaldehyde, along with co-enzyme TPP, the cofactor required is (a) Mg++ (b) Mn++ ++ (c) Fe (d) Zn++. 7. An international treaty known as Montreal Protocol was signed to control emission of (a) uV rays (b) ozone (c) CFC (d) oxygen. 8. Chloroplasts in higher plants are ________ shaped. (a) kidney (b) lens (c) bean (d) dome 24

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9. Pollen grain develops from _________ of anther. (a) epidermis (b) endothecium (c) tapetum (d) sporogenous tissue 10. In processing of eukaryotic hnRNA, during protein synthesis tailing involves __________ of RNA. (a) addition of adenylate residues at 3’ end (b) addition of methyl guanosine triphosphate at 3’ end (c) addition of methyl guanosine triphosphate at 5’ end (d) removal of introns 11. In a cross between red kernelled and white kernelled varieties of wheat showing polygenic inheritance the phenotypic ratio in F2 generation will be (a) 1 : 6 : 15 : 20 : 15 : 6 : 1 (b) 1 : 4 : 6 : 4 : 1 (c) 1 : 2 : 1 (d) 2 : 1. 12. In angiosperms during development of embryo the suspensor cells develop from (a) oospore (b) integument (c) endosperm (d) cotyledon. 13. Manganese, calcium and chloride ions present in PSII play an important role in (a) absorption of light (b) CO2 assimilation (c) photolysis of water (d) ATP synthesis. 14. Which process does the following equation represent ? C6H12O6 + 2NAD + 2 ADP + 2 Pi → 2 CH3 – CO – COOH + 2 NADH2 + 2 ATP (a) Complete glycolysis (b) Complete aerobic respiration (c) Complete anaerobic respiration (d) Complete fermentation 15. The cloning vector M13 has genetic material (a) ssRNA (b) dsRNA (c) ssDNA (d) dsDNA.

16. Earthworm is a (a) herbivore (c) tertiary consumer

(b) secondary consumer (d) detritivore.

17. To induce formation of organs in a callus it is necessary to provide (a) growth hormones (b) water (c) soil (d) antibiotics. 18. Anemophily is not observed in (a) maize (b) jowar (c) sugar cane (d) Salvia. 19. In an ecosystem, the biotic components herbivores are (a) photosynthetic (b) chemosynthetic (c) macroconsumers (d) microconsumers. 20. The visible portion of light spectrum useful in photosynthesis is referred to as (a) RFlP (b) PAR (c) VAM (d) VNTR. 21. The microbe Pseudomonas denitrificans produces vitamin (a) K (b) D (c) B2 (d) B12. 22. If there are 1280 microspores in a tetralocular anther, how many microspore mother cells will be there in its each pollen chamber ? (a) 80 (b) 160 (c) 240 (d) 1280 23. Which one of the following plants does not help in vegetative propagation by leaves ? (a) Begonia (b) Kalanchoe (c) Bryophyllum (d) Oxalis 24. Given below are some reactions and the enzymes involved. Identify the correct pairs. Column I Column II 1. Fructose 1, 6 diphosphate A. Enolase → 3PGAl + DHAP 2. Citrate → Cis-aconitate B. Thiokinase 3. Succinyl Co A → Succinate C. Aconitase 4. 2 PGA → PEP D. Aldolase (a) 1-D, 2-C, 3-B, 4-A (b) 1-A, 2-B, 3-C, 4-D (c) 1-B, 2-A, 3-D, 4-C (d) 1-C, 2-D, 3-A, 4-B 25. Human skin colour is an example of (a) intragenic interaction (b) interallelic interaction (c) quantitative inheritance (d) pleiotropy. 26. During DNA replication, the addition of nucleotides on the lagging strand occurs (a) towards the replicating fork (b) at a faster rate than leading strand (c) continuously (d) discontinuously.

27. The technique of producing large number of genetically similar plants within short time by tissue culture is called (a) organogenesis (b) somatic hybridisation (c) micropropagation (d) protoplast culture. 28. How many sense codons code for 20 known essential amino acids ? (a) 61 (b) 62 (c) 63 (d) 64 29. Which one of the following is not a natural method of vegetative propagation ? (a) Runner (b) Foliar buds (c) Stem tuber (d) Grafting 30. Transposons are sequences of (a) DNA (b) mRNA (c) rRNA (d) tRNA. 31. A 340 Å long segment of DNA molecule has 20 thymine nitrogenous bases, what will be the number of guanine nitrogen bases in the same segment ? (a) 10 (b) 40 (c) 80 (d) 160 32. The final electron acceptor during ETS in respiration is (a) hydrogen (b) oxygen (c) FMN (d) ubiquinone. 33. The time taken from the fixation of CO2 to the formation of one glucose molecule is about _________ seconds. (a) 20 (b) 40 (c) 60 (d) 90 34. The secondary metabolite obtained from Catharanthus roseus is (a) vincristine (b) anthocyanin (c) menthol (d) nicotine. 35. large stout, nocturnal flowers producing copious nectar and emitting fermenting fruity odour, are the adaptations for (a) entomophily (b) ornithophily (c) chiropterophily (d) anemophily. 36. During biogas production acetic acid is transformed into the final product by the enzymes of (a) Clostridium (b) Pseudomonas (c) Penicillium (d) Methanobacillus. 37. The gymnospermic endosperm differs from an angiospermic endosperm because in gymnosperms it is (a) haploid and developed from female gametophyte (b) diploid and developed from female gametophyte (c) triploid and developed after fertilisation (d) triploid and developed before fertilisation. MT BIOLOGY

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38. What is not true about emasculation of a flower while performing an artificial cross ? (a) It is removal of anthers from flower. (b) It is done before anthesis. (c) It is to avoid self pollinaton. (d) It is done in flowers of plants selected as male parent. 39. Pusa Shubhra is a variety of (a) cauliflower (b) chilli (c) wheat (d) cabbage. 40. Which of the following is correct pair of pyrimidine bases? (a) Adenine and thymine (b) Adenine and guanine (c) Thymine and cytosine (d) Guanine and cytosine 41. In the nomenclature of enzyme restriction endonuclease the Roman numeral indicates (a) number of times it is used (b) the order of discovery from source (c) number of cuts on DNA (d) number of recombinants formed. 42. Environmental biotic factor that helps in pollination is (a) air (b) water (c) wind (d) insect. 43. How many types of gamete will be produced by an individual having genotype AaBbcc ? (a) Four (b) Three (c) Two (d) One 44. Self pollination which involves two different flowers of the same plant, is called (a) autogamy (b) geitonogamy (c) xenogamy (d) hybridisation. 45. The initial step in preparation of beer is (a) malting (b) carboxylation (c) clarification (d) distillation. 46. A desirable change in genotype of an organism is obtained by (a) DNA replication (b) protein synthesis (c) rDNA technology (d) mRNA formation. 47. Considering mode of asexual reproduction, match the Column I with Column II and select the correct option. A. B. C. D. (a) (c) 26

Column I yeast Penicillium Filamentous algae Chlamydomonas A-iii, B-iv, C-i, D-ii A-iv, B-iii, C-ii, D-i MT BIOLOGY

Column II i. Fragmentation ii. Zoospores iii. Budding iv. Conidia (b) A-ii, B-iii, C-i, D-iv (d) A-iii, B-ii, C-i, D-iv

TODAY | July ‘15

48. How much of the energy released during aerobic respiration is approximately conserved in the form of ATP ? (a) 20% (b) 40% (c) 60% (d) 100% 49. The deflection of pitch angle between two successive steps (rungs) of DNA is (a) 72° (b) 54° (c) 36° (d) 18°. 50. Which one of the following is a CAM plant ? (a) Maize (b) Kalanchoe (c) Sugar cane (d) Jowar 51. One of the following cells secretes a hormone (a) cells of leydig (b) cells of Sertoli (c) primary spermatocyte (d) secondary spermatocyte. 52. Find the odd one out, with respect to X-linkage. (a) Haemophilia (b) Myopia (c) Nephritis (d) Night blindness 53. The first fossil of Australopithecus was discovered in (a) Olduvai Gorge, Tanzania (b) Fayum deposits of Egypt (c) Siwalik hills in India (d) Tuang in South Africa. 54. Which of the following options are correct ? 1. Heroin

– Stimulant

2. Marijuana

– Cardiovascular

3. Cocaine

– Hallucinations

4. Morphine (a) 1, 2 and 3 (c) 2, 3 and 4

– Sedative (b) 1, 3 and 4 (d) 1, 2, and 4

55. Serotonin and melatonin are hormones, secreted by (a) pancreas (b) pineal body (c) pituitary gland (d) thymus. 56. The characters such as pointed elongated snout, and strong and stout forelimbs, well developed claws are observed in __________ adaptation. (a) arboreal (b) aerial (c) cursorial (d) fossorial 57. Deposition of ________ in the joints causes gout. (a) urea (b) uric acid (c) guanine (d) ammonia 58. The glycoprotein, fertilizin is secreted by (a) ovum (b) ovary (c) sperm (d) testis.

59. In the given diagram I and II indicate

67. More than 95% of transgenic animals are (a) rabbits (b) mice (c) fish (d) cows. 68. Pick the odd homologous pair out. (a) Bartholin’s Gland – Cowper’s Gland (b) Clitoris – Penis (c) Mons pubis – Glans penis (d) labia majora – Scrotum 69. Which is not the function of lymph? (a) Transport RBCs (b) Drain excess tissue fluid (c) Transport lymphocyte and antibodies (d) Transport absorbed fat

(a) (b) (c) (d)

chromomere and chromonemata centromere and secondary constriction secondary constriction and satellite telomere and satellite.

60. Find the correct match. Column A Column B i. Mackeral Rastrelliger ii. Honey bee Apis iii. Mirgal Tacchardia iv. Silkworm Bombyx (a) ii and iv (b) i and ii (c) iv only (d) i and iii

Column C Freshwater fish Wax Marine water fish Mulberry silk

70. A cuckoo laying eggs in the nest of other species of birds, is an example of (a) adelphoparasitism (b) broodparasitism (c) ectoparasitism (d) hyperparasitism. 71. The reptiles, like dinosaurs were dominant in _________ period. (a) cretaceous (b) jurassic (c) tertiary (d) triassic 72. Select the correct identification group of labelled parts I, II, III.

61. A Red list of endangered species is maintained by (a) CSIR (b) IuCN (c) NEERI (d) WlS. 62. The Human Genome Project (HGP) was initiated in (a) 1988 (b) 1990 (c) 1992 (d) 1994. 63. Ectoderm gives rise to (a) cornea, heart, bronchi, dentine (b) adrenal cortex, tongue, liver, retina (c) lungs, adrenal medulla, dermis, thyroid (d) enamel of teeth, nails, adrenal medulla, hair. 64. Helper T – cells : lymphokines as Killer T – cells : __________ (a) Interferons (b) lysozymes (c) Perforins (d) Prostaglandins 65. Epicanthal skin fold and simian crease are characteristics of (a) Down’s syndrome (b) Klinefelter’s syndrome (c) Thalassaemia (d) Turner’s syndrome. 66. Following are all breeds of cows except (a) Jersey (b) Nagpuri (c) Sahiwal (d) Sindhi.

(a) (b) (c) (d)

I – Scala vestibuli, II – Scala media, III – Scala tympani I – Scala vestibuli, II – Scala tympani, III – Scala media I – Scala tympani, II – Scala media, III – Scala vestibuli I – Scala media, II – Scala tympani, III – Scala media

73. The transgenic animals are generally produced for all of the following needs except (a) testing of chemical safety (b) testing of vaccine safety (c) stimulation of pathogenicity (d) production of pharmacologically important proteins. 74. Match the following. i. Mercury A. low blood pressure, blindness ii. lead B. Hyperkeratosis, liver cirrhosis iii. Arsenic C. Bone deformation, testicular atrophy iv. Cadmium D. Abdominal pain, haemolysis E. Anaemia, convulsions (a) i-E, ii-D, iii-C, iv-B (b) i-D, ii-E, iii-B, iv-C (c) i-C, ii-B, iii-D, iv-A (d) i-B, ii-C, iii-D, iv-E MT BIOLOGY

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75. Choose the correct group of labellings.

(a) (b) (c) (d)

I – Trophoblast, II – Archenteron, III – Micromeres I – Trophoblast, II – Blastocoel, III – Megameres I – Trophoblast, II – Archenteron, III – Inner mass cells I – Trophoblast, II – Blastocoel, III – Inner mass cells

76. All of the following animals are ureotelic except (a) frog (b) snake (c) turtle (d) toad. 77. The study of blood vessels is termed as (a) angiology (b) cardiology (c) haematology (d) histology. 78. Plasma cells are derived from (a) cytotoxic T – cells (b) helper T – cells (c) memory B – cells (d) memory T – cells. 79. Darwin’s theory of evolution cannot explain (a) arrival of fittest (b) natural selection (c) prodigality of production (d) struggle for existence. 80. During ovulation, the ovary releases (a) oogonia (b) ootid (c) primary oocyte (d) secondary oocyte. 81. Juxtaglomerular cells of kidney secrete hormone (a) angiotensinogen (b) angiotensin II (c) coherin (d) renin. 82. The marine fish among the following varieties is (a) Stromateus (b) Labeo (c) Cirrihina (d) Catla. 83. Which of the following animals was selected by Morgan for studying linkage ? (a) Apis indica (b) Agrobacterium tumefaciens (c) Drosophila melanogaster (d) E. Coli 84. The increase in blood flow to heart stimulates secretion of (a) renin (b) oxytocin (c) antidiuretic hormone (d) atrial natriuretic factor. 85. Heaviness with severe chest pain which may disappear with rest indicates (a) angina pectoris (b) atherosclerosis (c) arteriosclerosis (d) hyperthyroidism. 28

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86. The coordinator between nervous and endocrine system is (a) thalamus (b) hypothalamus (c) epithalamus (d) colliculus. 87. Match the pairs of diseases and pathogens. Column I Column II 1. Malaria a. Wuchereria bancrofti 2. Filariasis b. Helminth 3. Typhoid c. Plasmodium falciparum 4. Schistosomiasis d. Salmonella typhi (a) 1-c, 2-b, 3-a, 4-d (b) 1-d, 2-a, 3-b, 4-c (c) 1-a, 2-b, 3-c, 4-d (d) 1-c, 2-a, 3-d, 4-b 88. The clot formation can be prevented by treatment with ________ in gene therapy. (a) DNase (b) recombinant vaccine (c) TPA (d) TGF-B 89. Select the correct match. (a) Gibbon – Cercopithecoidea (b) lemur – Prosimii (c) New World Monkey – Hominoidea (d) Tarsier – Anthropoidea 90. Atrial Natriuretic Factor (ANF) decreases (a) blood pressure (b) secretion of renin (c) Na+ excretion (d) vasodilation. 91. Morula formed at the end of cleavage is ________ celled. (a) 14 (b) 16 (c) 18 (d) 20 92. Select the correct pair. (a) Adaptive radiation – Darwin’s Finches (b) Connecting link – Sewall – Wright effect (c) Genetic drift – Peppered moth (d) Industrial melanism – Archaeopteryx 93. How many pairs of sympathetic ganglia are present in ANS ? (a) 10 (b) 12 (c) 22 (d) 31 94. The first vaccine produced by Edward Jenner, was for protection against (a) hepatitis (b) influenza (c) chicken pox (d) small pox. 95. Which are the phagocytic cells from given diagram ?

(a) I and V (c) I and IV

(b) I and III (d) I and II

96. Forceful muscular contractions of uterine wall is involved in (a) implantation (b) lactation (c) micturition (d) parturition.

Answer

Key

1.

(b)

2.

(d)

3.

(b)

4.

(a, c) 5.

97. In mechanism of hormone action, which of the following is not a second messenger ? (a) Cyclic AMP (b) IP3 (c) Ca++ (d) Mg++

6.

(a)

7.

(c)

8.

(b)

9.

(d)

10. (a)

98. One of the following pair of animals is an example of commensalism. (a) Sacculina – Crab (b) Plasmodium – Anopheles (c) Golden Jackal – Tiger (d) Ascaris – Man 99. What is “afterbirth” referred to ? (a) Amniotic fluid passing out (b) Expulsion of baby (c) Expulsion of placenta, umbilical cord and foetal membrane (d) Secretion of hormone relaxin 100. Which group of cranial nerves control eye ball movements ? (a) Optic, Abducens, Pathetic (b) Optic, Oculomotor, Trochlear (c) Oculomotor, Abducens, Auditory (d) Oculomotor, Abducens, Trochlear

(b)

11. (b)

12. (a)

13. (c)

14. (a)

15. (c)

16. (d)

17. (a)

18. (d)

19. (c)

20. (b)

21. (d)

22. (a)

23. (d)

24. (a)

25. (c)

26. (d)

27. (c)

28. (a)

29. (d)

30. (a)

31. (c)

32. (b)

33. (d)

34. (a)

35. (c)

36. (d)

37. (a)

38. (d)

39. (a)

40. (c)

41. (b)

42. (d)

43. (a)

44. (b)

45. (a)

46. (c)

47. (a)

48. (b)

49. (c)

50. (b)

51. (a)

52. (c)

53. (d)

54. (c)

55. (b)

56. (d)

57. (b)

58. (a)

59. (d)

60. (a)

61. (b)

62. (b)

63. (d)

64. (c)

65. (a)

66. (b)

67. (b)

68. (c)

69. (a)

70. (b)

71. (b)

72. (a)

73. (c)

74. (b)

75. (d)

76. (b)

77. (a)

78. (c)

79. (a)

80. (d)

81. (d)

82. (a)

83. (c)

84. (d)

85. (a)

86. (b)

87. (d)

88. (c)

89. (b)

90. (a)

91. (b)

92. (a)

93. (c)

94. (d)

95. (a)

96. (d)

97. (d)

98. (c)

99. (c)

100. (d) 

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ACROSS 2. An antibiotic produced from Class Actinomycetes which was the first drug to be successful against tuberculosis. (12) 7. A light harvesting structure containing aggregates of photosynthetic accessory pigments that is located on the surface of thylakoid membranes in all cyanobacteria and red algae. (14) 8. A common benign tumour composed of well differentiated fat cells. (6) 9. A technique for in vitro fertilisation in which an individual sperm cell is introduced into an egg cell. (4) 12. The consumption of vegetation usually on grassland by animals particularly cattle and sheep. (7) 13. A group of cells, which can be microorganisms or of animal or plant origin, that are grown under specific conditions of nutrient levels, temperature, pH, oxygen levels, osmotic factors, light, pressure etc. (7) 15. An inherited pattern of behaviour that appears in a similar form in all normally reared individuals of the same sex and species. (6) 17. The aqueous fluid formed by the excretory organs of animals for the removal of metabolic waste products. (5) 21. The function or position of an organism or population within an ecological community. (5) 22. A white colloidal carbohydrate of high molecular weight that occurs in ripe fruit and vegetables. (6) 23. A bottom-living marine fish, commonly known as ‘Electric Ray’ which discharges electricity that is sufficient to make the prey unconscious. (7) 25. The angle between a branch or leaf and the stem it grows from. (4) 27. Tissue consisting of protein fibrils that may accumulate between cells in various animal tissues. (7) 28. They are one internode long small runners which are found in rosette plants at the ground or water level. (6) 29. A fleshy fruit that develops from either one or several fused carpels and contains one or many seeds. (5) 30. A scientist who crystallised Tobacco Mosaic Virus (TMV) for the first time. (7)

DOWN 1. 3. 4. 5.

The removal of introns and fusion of exons to form functional RNAs. (8) The number of infectious virus particles present in a suspension. (5) The third geological epoch of the Palaeocene period. (9) A technique of injecting substances into cells, cell organelles and other microscopic structures using a micropipette. (14)

6. The uptake of water by substances that do not dissolve in water, and results in swelling of the substance. (10) 10. Denoting a compound consisting of molecules that have only single bonds. (9) 11. A fat-soluble vitamin that cannot be synthesised by mammals and other vertebrates and must be provided in the diet. (7) 14. A neuron that has one main process, the axon, extending from its cell body. (8) 16. The outermost layer of cells of the body of an animal. (9) 18. A horizontal underground stem that often sends out roots and shoots from its nodes. (7) 19. Any enzyme that breaks down nucleic acids into nucleotides. (8) 20. A floral arrangement in which the ovary is completely enclosed by the receptacle so that stamen and perianth arise above it, from the top of the receptacle. (7) 24. The thickened horny forewings of the beetles, which cover and protect the membranous hindwings when the insect is at rest. (6) 26. A coenzyme derived from the vitamin B (nicotinic acid), that participates in many biological dehydrogenation reactions. (3) 

30

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Maximise your chance of success and your seat in AIPMT and other PMTs by reading this column. This section is specially designed to optimise your preparation by practising more and more. It is a unitwise series having chapterwise question bank, allowing you to prepare systematically and become more competent. Recall question or single concept question – indicated by a single finger. Application question or question which requires 2 or 3 concepts to solve - indicated by 2 fingers. Application question or question which requires 3 or more concepts - indicated by 3 fingers.

UNIT-I : DIVersITY IN The LIVING WOrLD chApTer-1 : The LIVING WOrLD Multiple choice Questions 1. Which of the following are twin characteristics of growth? A. Increase in mass B. Increase in number C. Differentiation of cells D. Organisation of cells (a) A and C (b) B and D (c) A and B (d) B and C 2. Which of the following is not considered as defining property of growth? (a) Consciousness (b) Cellular organisation (c) Metabolism (d) Reproduction 3. First step in taxonomy is (a) description of the organism (b) identification of the organism (c) nomenclature of the organism (d) classification of the organism. 4. The specific epithet of the scientific names Mangifera indica and Solanum nigrum are (a) Mangifera and Solanum, respectively (b) indica and nigrum, respectively (c) indica and Solanum, respectively (d) Mangifera and nigrum respectively.

5. Match Column-I with Column-II and select the correct option from the codes given below. Column-I Column-II A. Binomial nomenclature (i) Hippocrates B. The Darwin of the 20th (ii) Ernst Mayr century C. Father of botany (iii) linnaeus D. Father of medicine (iv) Theopharastus (a) A-(iii), B-(ii), C-(iv), D-(i) (b) A-(iii), B-(ii), C-(i), D-(iv) (c) A-(i), B-(ii), C-(iii), D-(iv) (d) A-(ii), B-(iii), C-(iv), D-(i) 6. Put these classification terms in sequence, starting with the group with the most variation. I. Class II. Genus III. Phylum IV. Species V. Family VI. Order (a) III, I, VI, V, II, IV (b) IV, II, V, VI, I, III (c) III, I, V, VI, II, IV (d) IV, II, VI, V, I, III 7. Binomial nomenclature was given by (a) lamarck (b) linnaeus (c) Darwin (d) Tijo and levan. 8. Select the incorrect match from the following. (a) (b) (c) (d)

Common Name Mango Wheat Cat Housefly

Genus Mangifera Triticum Panthera Musca

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Family Anacardiaceae Poaceae Felidae Muscidae

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9. Select the mismatched pair. (a) Historia Plantarum (b) Systema Naturae (c) Historia Naturalis (d) Historia Generalis Plantarum

18. Hippocrates introduced and defined the word ‘species’. – – – –

Hippocrates linnaeus Pliny the Elder John Ray

10. A group of individuals, which are able to breed among themselves and produce their own kind is known as (a) Genus (b) Species (c) Family (d) Order. 11. ‘Taxa’ differs from ‘taxon’ due to (a) this being a higher taxonomic category than taxon (b) this being the lower taxonomic category than taxon (c) this being the plural of taxon (d) this being the singular of taxon. 12. Family is placed between (a) Order and Genus (b) Genus and Species (c) Class and Order (d) Phylum and Class. 13. ‘Key’ is a taxonomical aid used for the identification of organisms. Each statement in key is called _______. (a) couplet (b) lead (c) both (a) and (b) (d) none of these 14. Match Column-I with Column-II and select the correct option from the codes given below. Column-I Column-II A. Botanical garden (i) Preserved plant specimens B. Zoological park (ii) Preserved plant and animal specimens C. Museum (iii) living plants D. Herbarium (iv) living wild animals (a) A-(i), B-(ii), C-(iii), D-(iv) (b) A-(iii), B-(iv), C-(ii), D-(i) (c) A-(iii), B-(iv), C-(i), D-(ii) (d) A-(i), B-(ii), C-(iv), D-(iii) 15. Which of the following is the largest herbarium? (a) New york Botanical Garden (b) Royal Botanical Garden, Kew (c) Madras Herbarium, Coimbatore (d) Herbarium of National Botanical Research Institute, lucknow.

True or False 16. Metabolic reactions can be carried out outside the body of an organism in cell free systems. 17. living organisms show internal growth due to addition of materials and formation of cells inside the body, i.e., intussusception. 32

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19. Hornbill (a bird) is the symbol of the Bombay Natural History Society. 20. Modern taxonomy studies primitiveness, advancement and interrelationships of species. 21. Sir Julian Huxley is the father of new systematics. 22. Subspecies or variety is a distinct breeding subgroup of species having certain distinguishing characteristics that separate its members from other members of species. 23. Family is a taxonomic category which contains one or more related genera. 24. Natural History Museum is located in Chicago. 25. Herbarium is a store house of collected plant specimens that are dried, pressed and preserved on sheets.

Match The columns 26. Match Column I with Column Column I A. Impressions and remains of microorganisms B. Binomial nomenclature C. Genera with single Species D. unit of classification which may represent any level E. Taxonomic category containing one or more related orders

II. (i)

Column II linnaeus

(ii) Monotypic (iii) Taxon (iv) Class

(v) Microfossils

27. Match Column I with Column II. (There can be more than one match for items in Column I) Column I Column II A. linnaeus (i) Systema Naturae B. Defining property of (ii) Response to stimuli living organisms C. Pliny the Elder (iii) First system of artificial classification D. Taxonomic aids (iv) Botanical gardens E. Family (v) Species Plantarum (vi) Consciousness (vii) Historia Naturalis (viii) Museum (ix) Taxonomic category containing one or more related genera (x) Placed between order and genera in taxonomic hierarchy

passage Based Questions 28.(A) Complete the given passages with appropriate words or phrases. Growth is an (i) increase in mass of an individual. In unicellular organisms (ii) is the means of growth as well as reproduction. In multicellular organisms growth and reproduction are mutually (iii) . living organisms show internal growth due to addition of materials and formation of cells inside the body. Such a method is called (iv). Chemically growth is the result of difference between (v) and (vi) . (vii) can occur when catabolism exceeds anabolism. (B)

Read the given passage and correct the errors, wherever present. According to the rules of binomial nomenclature each organism is given two names consisting of the two words, generic and specific. Two species belonging to same genus can have similar specific names. The specific name is written first followed by generic name. Generic name begins with a small letter whereas specific name begins with a capital letter. Scientific names are derived from Spanish language.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 29. Assertion : Organisms are named according to binomial nomenclature. Reason : Scientific name consists of two words, one generic and other vernacular. 30. Assertion : New names in binomial nomenclature are derived from latin language or are latinised. Reason : latin language is dead and will not change in form or spellings with the passage of time. 31. Assertion : Reproduction cannot be an all-inclusive defining characteristic of living organisms. Reason : There are many living organisms which do not reproduce e.g., mules, sterile worker bees, etc.

32. Assertion : The taxonomic hierarchy includes seven obligate categories viz. Kingdom, Phylum or Division, Class, Order, Family, Genus and Species. Reason : Subkingdom, Subphylum or Subdivision, Subclass, Suborder, etc are intermediate categories. 33. Assertion : Solanum is a polytypic genus. Reason : Solanum has a large number of closely related species, e.g., S.nigrum, S.tuberosum, S.melongena, etc. 34. Assertion : Petunia and Datura show some similarities. Reason : Petunia and Datura are placed in the same Family Brassicaceae. 35. Assertion : Botanical garden is a store house of collected plant specimens that are dried, pressed and preserved on sheets. Reason : Herbarium is a specialised garden having collections of living plants for reference. 36. Assertion : Classical taxonomy studies evolution and interrelationships of species. Reason : Classical taxonomy considers species to be dynamic. 37. Assertion : Monograph is a treatise having all information about a particular taxon. Reason : Manual is a handy book containing information for identification of names of species found in an area. 38. Assertion : Systematics is the branch of biology that deals with classification of organisms. Reason : Aim of classification is to group the organisms in an orderly manner.

Figure Based Questions 39. Refer the given table, which shows different organisms with their taxonomic categories and answer the following questions. Common Name

Biological Name

Family

Order

Class

Housefly

Musca domestica

A

Diptera

Insecta

Datura

Datura datura

Solanaceae

B

Dicotyledonae

Wheat

Triticum aestivum

Poaceae

Poales

C

Cat

D

Felidae

Carnivora

Mammalia

(a) Select the correct words for A, B, C and D. (b) Give the name of the one more Family belonging to Order B. (c) Give the name of another Genus belonging to Family A. MT BIOLOGY

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40. Refer the given flow chart and answer the following question.

(a) In the given flow chart A, B, C, D and E represent the characteristics features of herbarium, botanical garden, zoological park, museum and key respectively. Write the best suitable statements for A, B, C, D and E. (b) Identify the suitable words for (i), (ii), (iii), (iv), (v) and (vi).

chApTer-2 : BIOLOGIcAL cLAssIFIcATION Multiple choice Questions 1. In the 5-Kingdom classification, the Kingdom that includes the blue-green algae, nitrogen-fixing bacteria and methanogenic archaebacteria, is (a) Protista (b) Monera (c) Plantae (d) Fungi. 2. Bacteria are grouped under four categories according to their shape. Study the given figures and select the correct option regarding this.

(a) (b) (c) (d)

A Cocci Spirilla Bacilli Bacilli

B Bacilli Bacilli Spirilla Spirilla

C Spirilla Vibrio Vibrio Cocci

D Vibrio Cocci Cocci Vibrio

3. Why is a capsule advantageous to a bacterium? (a) It protects the bacterium from desiccation. (b) It provides means of locomotion. (c) It allows bacterium to “hide” from host’s immune system. (d) Both (a) and (c). 34

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4. Which of the following statements is incorrect? (a) Pathogenic bacteria cause 90% of human diseases. (b) A large number of antibiotics are produced by Actinomycetes (e.g, Streptomyces), which are a Class of Fungi. (c) N2-fixing bacteria pick up free N2 from soil atmosphere and convert it into nitrogenous compounds. (d) Archaebacteria differ from other bacteria in having a different cell wall structure and this feature is responsible for their survival in extreme conditions. 5. In which of the following groups, the mode of nutrition is both autotrophic and heterotrophic? (a) Fungi (b) Animalia (c) Monera (d) Both (a) and (b) 6. Read the given statements. A. Artificial system studies homology in characters viz. morphology, anatomy, molecular systematics, etc. B. Natural system gives information about both natural relationships and phylogeny. C. Natural system uses habit and habitat as criteria for classification. D. Artificial system often results in placing of unrelated organisms in a group. Of the above statements (a) A and B are correct, C and D are incorrect (b) B and D are correct, A and C are incorrect. (c) A, B and D are correct, C is incorrect (d) A, B and C are correct, D is incorrect. 7. Five kingdoms of Whittaker were based on (a) nutrition (b) structural complexity (c) ecological role (d) all of these. 8. Which of the following organisms have been placed under Kingdom Protista ? (a) Chrysophytes and dinoflagellates (b) Euglenoids (c) Slime moulds and protozoans (d) All of these 9. Study the given figure showing structure of Euglena, and select the option that correctly identifies A, B, C and D.

A (a) Cytostome

B

C

Photoreceptor Paramylum bodies (b) Contractile Photoreceptor Paramylum vacuole bodies (c) Cytostome Stigma Paramylum bodies (d) Cytostome Stigma Myonemes

D Myonemes Chloroplast Chloroplast Chloroplast

10. Which of the following statements regarding the Class Phycomycetes is correct? (a) These are found in aquatic habitats and on decaying wood in moist and damp places or as obligate parasites on plants. (b) Mycelium in these fungi is aseptate and coenocytic. (c) Asexual reproduction occurs by motile zoospores and by non-motile aplanospores. (d) All of these. 11. Study the given figure of structure of TMV (Tobacco Mosaic Virus) and select the option that correctly identifies the labellings A and B.

A B (a) ssDNA Capsomeres (b) dsDNA Capsomeres (c) ssRNA Capsomeres (d) dsRNA Tail fibres 12. Select the incorrect statement regarding heterocyst. (a) Heterocyst is a large sized thin walled cell occurring only at terminal position in filamentous cyanobacteria. (b) The wall of heterocyst is impermeable to oxygen but permeable to nitrogen. (c) Heterocyst contains enzyme nitrogenase and is specialised to perform nitrogen fixation. (d) PS II is absent in heterocyst. 13. Which of the following statements is true about viruses? (a) All viruses known to man are obligate parasites. (b) Some viruses have cellular structure and are saprophytes. (c) Viruses are filterable facultative parasites. (d) Viruses are capable of performing metabolic activities on their own.

14. Fungi can be distinguished from algae on the basis of (a) cellulosic cell wall and heterotrophic nature (b) chitinous cell wall and lacking chloroplast (c) heterotrophic food habit and chloroplast presence (d) none of the above. 15. Bryophytes comprise of (a) dominant phase of gametophyte which produces spores (b) small sporophyte phase and generally parasitic on gametophyte (c) sporophyte is of longer duration (d) dominant phase of sporophyte which is parasitic.

True or False 16. Classification based on evolutionary relationships of organisms is called phylogenetic system of classification. 17. An inert virus can be crystallised and stored indefinitely. 18. The viral genome gets integrated with host DNA in lytic phase of reproductive cycle of virulent phages. 19. The outer membrane of bacterial cell has hydrophilic channels of b-barrel proteins called porins. 20. Bacteria perform anoxygenic photosynthesis whereas cyanobacteria perform oxygenic photosynthesis. 21. Zygote is the only diploid structure in organisms having life cycle with gametic meiosis. 22. Euglenoids store their carbohydrates as paramylon, scattered throughout the cytoplasm. 23. The brown colour of brown algae is due to the presence of large amount of fucoxanthin. 24. In several cases, fungal hyphae get closely packed and lose their individuality to form a compact tissue called pseudoparenchyma. 25. Deuteromycetes are also called imperfect fungi because they show autrotophic mode of nutrition.

Match The columns 26. Match Column I with Column II. Column I Column II A. Cytotaxonomy (i) Based on characteristics of chemical constituents B. Chemotaxonomy (ii) Systematic classification based on evolutionary history C. Cladistics (iii) Divides organisms into Plantae, Protista and Animalia D. Three-domain (iv) Based on comparative system cytological studies E. Three Kingdom (v) Divides cellular life forms classification into archaea, bacteria and eukarya MT BIOLOGY

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27. Match Column I with Column II. (There can be more than one match for items in Column I) Column I Column II A. Glycocalyx (i) Attachment to a surface B. Bacteria causing (ii) Thermoplasma disease in plants C. Bacteria having (iii) Cleaning agents in tooth dual ability to paste tolerate high temperature as well as acidity D. Diatomite (iv) Added to paints for enhancing night visibility E. Alginic acid (v) Thermoproteus (vi) Xanthomonas citri (vii) Macrocystis (viii) Protection from toxic chemicals and drugs (ix) Agrobacterium tumefaciens (x) Sargassum

(b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 29. Assertion : Mycoplasma are pathogenic in animals and plants. Reason : Mycoplasma lack cell wall and can survive 30.

31.

32.

passage Based Questions 28.(A) Complete the given passage with appropriate words or phrases. Algae do not occur generally in dry (i) habitats. They usually possess (ii) and are (iii) in nutrition. Their cell walls are made up of true (iv) . Food reserve in algae is (v) or related polysaccharide and (vi) . (vii) spores and gametes are quite common in the members of this group. (B)

34.

Read the given passage and correct the errors, wherever present.

35.

Sclerotia and rhizomorphs are the means of sexual reproduction in fungi. Rhizomorphs are perennating bodies made up of compact masses of hyphae whereas sclerotia are rope like twisted subterranean masses of hyphae. Vegetative reproduction in fungi occurs through spores. The sexually produced spores are called mitospores,e.g., basidiospores, conidia, etc. Asexually produced spores are called meiospores, e.g., ascospores, chlamydospores etc.

36.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A 36

33.

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37.

38.

without oxygen. Assertion : Viroids are small infectious RNA particles which are devoid of protein coat. Reason : Viroids contain more than 900 nucleotides and do not contain any genes. Assertion : Hopanoids are pentacyclic sterols found in plasma membrane of some bacteria. Reason : Hopanoids stabilise the plasma membrane. Assertion : Halobacterium is able to live under high salt conditions like salt beds, salt marshes, etc. Reason : Halobacterium contains red carotenoid pigment in its cell membranes which protects it against harmful solar radiations and also lacks sap vacuoles hence can avoid plasmolysis. Assertion : Euglenoids pile up at the bottom of water reservoirs and from big heaps called diatomite. Reason : The reserve food material of euglenoids is in the form of volutin globules. Assertion : In many Basidiomycetes the central septal pore possesses a barrel shaped inflation known as dolipore septum. Reason : Septal pores allow movement of substances between adjacent cells. Assertion : Dikaryotic cells in fungi represent intervening stage between plasmogamy and karyogamy and contain two haploid nuclei. Reason : Fungal cellulose or chitin is basically made up of acetyl glucosamine. Assertion : In lichens, mycobiont and phycobiont are symbiotically associated in which algae is predominant and fungi is a subordinate partner. Reason : The fungus provides food and alga protects the fungus from unfavourable conditions. Assertion : Individuals of sporozoa lack locomotory organs. Reason : All sporozoans are parasites. Assertion : Kingdom Protista includes all eukaryotic organisms. Reason : Membrane bound organelles and an organised nucleus is absent in Protista.

Figure Based Questions 39.

Refer the given figure of different types of fungal spores (A, B, C, D and E).

(a) Identify the type of spore represented by A, B, C, D, and E. (b) (i) Which of the above spores are motile spores? Give two examples of fungi in which they occur. (ii) Which spore is formed exogenously? Identify the Class of Fungi of which they are characteristic. (iii) Give examples of fungi in which spore C is found. (iv) Which spore is characteristic of Class Ascomycetes? 40. Refer the given figure and answer the following questions.

2. Which of the given genera is homosporous? (a) Cycas (b) Pinus (c) Selaginella (d) Lycopodium 3. Choose the correct statement. (a) Bryophytes can live in soil but are dependent on water for sexual reproduction. (b) The sex organs in bryophytes are unicellular. (c) In bryophyte the main plant body is a gametophyte which is differentiated into true root, stem and leaves. (d) Common example of liverwort is Polytrichum. 4. Prothallus of petridophytes is (a) conspicuous, small, multicellular, free-living, photosynthetic thalloid gametophyte (b) inconspicuous, small, multicellular, free-living, photosynthetic thalloid gametophyte (c) inconspicuous, large, unicellular, free-living, photosynthetic thalloid gametophyte (d) inconspicuous, small, multicellular, free-living, non-photosynthetic thalloid saporophyte. 5. Identify the given figures of algae and select the correct option.

A (a) (b) (c) (d)

(a) The given life cycles, (A and B) are found in protists. Identify the type of cycle A and B. (b) Give the examples of groups in which these two cycles (A and B) are found respectively (c) Differentiate between life cycle A and B.

chApTer-3: pLANT kINGDOM Multiple choice Questions 1. Which of the following is responsible for peat formation? (a) Marchantia (b) Riccia (c) Funaria (d) Sphagnum

Fucus Dictyota Dictyota Porphyra

B Polysiphonia Polysiphonia Porphyra Polysiphonia

6. What is common in all the three, Funaria, Dryopteris and Ginkgo? (a) Presence of archegonia (b) Well developed vascular tissues (c) Independent gametophyte (d) Independent sporophyte 7. Consider the following statements with respect to gymnosperms and angiosperms. A. Double fertilisation is an event unique to gymnosperms. B. Angiosperms range in size from microscopic Wolffia to tall trees of Sequoia. C. In gymnosperms the seeds are not covered. D. The gymnosperms are heterosporous. MT BIOLOGY

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Of the above statements (a) A and B alone are correct (b) C alone is correct (c) B and C alone are correct (d) C and D alone are correct. 8. Examine the figure given below and select the correct option giving all the four parts (A, B, C and D) rightly identified.

A B C D (a) ArchegoFemale Gemma Rhizoids niophore thallus cup (b) ArchegoFemale Bud Food niophore thallus (c) Seta Sporophyte Protonema Rhizoids (d) AntheridMale Globule Roots iophore thallus 9. Selaginella and Salvinia are considered to represent a significant step toward evolution of seed habit because (a) female gametophyte is free and gets dispersed like seeds (b) female gametophyte lacks archegonia (c) megaspores possess endosperm and embryo surrounded by seed coat (d) embryo develops in female gametophyte which is retained on parent sporophyte. 10. Compared with the gametophytes of the bryophytes, the gametophytes of vascular plants tend to be (a) smaller but have larger sex organs (b) larger but have smaller sex organs (c) larger and have larger sex organs (d) smaller and have smaller sex organs. 11. Examine the figures A, B, C and D. In which one of the four options all the items A, B, C and D are correct?

(a) (b) (c) (d)

A Chara Equisetum Selaginella Funaria

B Marchantia Ginkgo Equisetum Adiantum

C Fucus Selaginella Salvinia Salvinia

D Pinus Lycopodium Ginkgo Riccia

12. In plants showing diplontic life cycle (a) sporophytic generation is represented by one-celled zygote (b) gametophyte is dominant free living and photosynthetic (c) sporophyte is dominant, photosynthetic and independent (d) none of these. 13. Gymnosperms are referred to as “naked seed plants” because (a) they lack ovule (b) they lack ovaries (c) they lack pollen grains (d) they lack archegonia. 14. Coralloid roots associated with N2 fixing cyanobacteria are found in (a) Equisetum (b) Marchantia (c) Cycas (d) Lycopodium. 15. Haplo-diplontic life cycle is found in (a) Bryophytes (b) Pteridophytes (c) both (a) and (b) (d) none of these.

True or False 16. The plant body of mosses, may be thallose or foliose. 17. Archegonia are female organs of Bryophytes, Pteridophytes and Gymnosperms. 18. In Funaria, the male receptacle is surrounded by rosette of divergent perichaetial leaves. 19. In Pteridophytes, sperms are generally bi or multiflagellate. 20. Ferns are grown as ornamental plants for their delicate and graceful leaves. 21. Heterospory is pre-requisite to pollination and seed formation. 22. A distinct ovary, style and stigma is absent in Gymnosperms. 23. In Gymnosperms, phloem is without sieve tubes. 24. young leaves of Cycas show circinate ptyxis. 25. In Angiosperms the development of endosperm takes place before fertilisation and hence it is haploid.

38

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Match The columns 26. Match Column I with Column II. Column I Column II A. Carpospores (i) Ectocarpus B. Fouling of ships (ii) Sphagnum C. Coenobium (iii) Equisetum D. Peat moss (iv) Porphyra E. Scouring (v) Volvox F. Ephedrine (vi) Ephedra 27. Match Column I with Column II. (There can be more than one match for items in Column I) Column I Column II A. Agar (i) Gelidium B. Food supplement (ii) Selaginella for space travellers C. Heterosporous (iii) Chlorella pteridophytes D. Triploid (iv) Salvinia endosperm E. Dwarf shoots (v) Eucalyptus (vi) Gracilaria (vii) Spirulina (viii) Acacia (ix) Pinus (x) Ginkgo

passage Based Questions 28.(A) Complete the given passage with appropriate words or phrases.

(B)

The plant body of liverworts is (i) and may be (ii) or (iii). leaves when present are without (iv) and branching is generally (v) . (vi) are present in capsule of liverworts whereas (vii) are absent. Read the given passage and correct the errors wherever present. Ferns are seed producing vascular plants which inhabit dry areas. They constitute the smallest living group of primitive vascular plants. Ferns dominated the earth in permian period. leaves are large and called ramenta. Mature leaves show circinate ptyxis. younger parts of their stem, leaves and petiole possess hairs called fronds.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as :

(a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 29. Assertion : In Angiosperms, the sporophylls are aggregated to form flowers. Reason : In Gymnosperms, the sporophylls are aggregated to form cones. 30. Assertion : Syngamy is generative fertilisation and triple fusion is vegetative fertilisation in Angiosperms. Reason : Both male and female gametes are involved in syngamy whereas only one male gamete and two vegetative nuclei are involved in triple fusion. 31. Assertion : In Angiosperms, all the cells of embryo sac are haploid. Reason : In Angiosperms, embryo sac formation is preceded by meiosis. 32. Assertion : Cycas is also called living fossil. Reason : Cycas possesses a number of characters of extinct Pteridosperms and Cycads. 33. Assertion : True stem and leaves are absent in Bryophytes. Reason : In Bryophytes sporophyte is parasitic over gametophyte. 34. Assertion : Bryophytes especially mosses form dense mats over the soil and prevent soil erosion. Reason : Marchantia often grows in acidic marshes and produces peat. 35. Assertion : Gymnosperms do not attain great heights. Reason : Roots and vascular tissues are absent in Gymnosperms. 36. Assertion : Both green algae and higher plants possess the same type of chlorophylls, a and b. Reason : Cell walls of higher plant possess cellulose whereas algal cell walls are made up of chitin. 37. Assertion : Colony of Volvox called coenobium is hollow and has fixed number of cells. Reason : The alga Volvox rotates during swimming, therefore also known as rolling alga. 38. Assertion : In green algae sexual reproduction occurs through palmella stage. Reason : In palmella stage two flagellated, thick walled cellls lie close to each other embedded in mucilagenous mass. MT BIOLOGY

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Figure Based Questions Given below is the diagrammatic haplontic life cycle of Chlamydomonas.

3. Match the following list of animals with their level of organisation and choose the correct sequence. Column I Column II A. Organ level (p) Pheretima B. Cellular level (q) Fasciola C. Tissue level (r) Spongilla D. Organ system level (s) Obelia (a) A - (s), B - (r), C - (p), D - (q) (b) A - (s), B - (q), C - (r), D - (p) (c) A - (q), B - (s), C - (r), D - (p) (d) A - (q), B - (r), C - (s), D - (p) 4. Which of the following is a common feature of mammals? (a) They undergo moulting. (b) They have seven cervical vertebrae. (c) They are carnivores. (d) They have ventral nerve cord. 5. In which one of the following, the genus name, its two characters and its Phylum are not correctly matched, whereas the remaining three are correct? Genus name Characters Phylum (a) Pila

Refer the given life cycle and answer the following questions. 39. (a) In the given cycle, what do phase I and phase II represent respectively? (b) Identify structures X, y and Z. Give the characteristic features of X. 40. (a) Describe the processes P, Q and R. (b) Identify the process S. (c) What kind of life cycle does Chlamydomonas exhibit? Justify your answer.

chApTer-4: ANIMAL kINGDOM Multiple choice Questions 1. The kind of coelom represented in the diagram given below is characteristic of

(a) roundworm (b) earthworm (c) tapeworm (d) cockroach. 2. Choose the wrong statement. (a) Teeth in Chondrichthyes are modified ctenoid scales. (b) Air bladder in Osteichthyes regulates buoyancy. (c) In amphibians, the tympanum represents the ear. (d) long bones in birds are pneumatic. 40

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(b) Asterias

(c) Sycon

(i) (ii) (i) (ii)

(i) (ii) (d) Periplaneta (i) (ii)

Body segmented Mollusca Mouth with radula Spiny skinned Echinodermata Water vascular system Pore bearing Porifera Canal system Jointed appendages Arthropoda Chitinous exoskeleton

6. Body cavity of Coelenterata is called (a) haemocoel (b) spongocoel (c) coelenteron (d) pseudocoelom. 7. The non-cellular layer present between pinacoderm and choanoderm in body wall of poriferans is known as (a) mesoderm (b) middle lamellae (c) mesenchyme (d) none of these. 8. Which one of the following categories of animals, is correctly described with no single exception in it? (a) All reptiles possess scales, have a three chambered heart and are cold blooded (poikilothermal). (b) All bony fishes have four pairs of gills and an operculum on each side. (c) All sponges are marine and have collared cells. (d) All mammals are viviparous and possess diaphragm

for breathing. 9. Chordates differ from nonchordates in having (a) notochord (b) dorsal hollow nerve cord (c) pharyngeal gill slits (d) all of these.

10. Study carefully the given flowchart and fill in the blanks (A), (B), (C), (D) and (E).

(c) A-liver fluke; B-Male roundworm; C-Nereis; D-Hirudinaria (d) A-liver fluke; B-Female roundworm; C-Nereis; D-Hirudinaria

True or False 16. Coelenterates have organ system level of body organisation. 17. Roundworms, annelids and molluscs are protostomes. 18. Porifers and cnidarians are diploblastic animals as their embryos have two germinal layers, ectoderm and endoderm. A (a) (b) (c) (d)

Cellular level Cellular level Cellular level Cellular level

B Bilateral symmetry Radial symmetry Bilateral symmetry Radial symmetry

C Radial symmetry Bilateral symmetry Radial symmetry Bilateral symmetry

D

E

PseudoCoelomates coelomates Coelomates Pseudocoelomates Coelomates Pseudocoelomates PseudoCoelomates coelomates

11. In most simple type of canal system of Porifera, which of the following ways exhibit water flow? (a) Ostia → Spongocoel → Osculum → Exterior (b) Spongocoel → Ostia → Osculum → Exterior (c) Osculum → Spongocoel → Ostia → Exterior (d) Osculum → Ostia → Spongocoel → Exterior 12. Amphibians share with reptiles all of the following characters except (a) ventral heart (b) external fertilisation and indirect development (c) dioecious, oviparous (d) cold blooded or poikilotherms. 13. Which of the following is a hemichordate? (a) Herdmania (b) Doliolum (c) Balanoglossus (d) Branchiostoma 14. Prototherian mammals like platypus are good examples for (a) viviparous type (b) oviparous (c) ovoviviparous type (d) parthenogenic type. 15. Identify the figures A, B, C and D and select the correct option.

(a) A-liver fluke; B-Male roundworm; C-Hirudinaria; D-Nereis (b) A-liver fluke; B-Female roundworm; C-Hirudinaria; D-Nereis

19. Pseudometamerism or false segmentation is characteristic of Phylum Annelida. 20. Internal fertilisation takes place in birds. 21. In indirect development, the young ones do not resemble the adults. 22. In spiders, exchange of gases takes place through book lungs. 23. Chitinous cuticle forms the exoskeleton in arthropods. 24. Cliona is commonly, called as “The Venus’ flower basket”. 25. Rod shaped bodies called rhabdites are present in the epidermal cells of Platyhelminthes.

Match The columns 26. Match Column I with Column II. Column I Column II A. Respiratory pigment (i) Frog haemocyanin B. Buccopharyngeal (ii) Pila respiration C. Renette cell (iii) King crab D. Book gills (iv) Ascaris E. Connules (v) Physalia F. Dactylozooids (vi) Spongia 27. Match Column I with Column II. (There can be more than one matches for items in Column I) Column I Column II A. Mouth circular (i) Petromyzon and jawless B. Placoid scales (ii) Scoliodon C. uropygial glands (iii) Struthio D. Marsupium (iv) Didelphis or brood pouch E. Presence of pinna (v) Chimaera (vi) Myxine (vii) Columba (viii) Rattus (ix) Macropus (x) Cavia MT BIOLOGY

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passage Based Questions 28.(A) Complete the given passage with appropriate words or phrases. Birds are (i) animals. Their (ii) are modified into wings. No (iii) is present in birds except uropygial glands at the base of (iv) . The upper and lower jaws in birds are modified into (v) . Their alimentary canal has additional chambers; (vi) for storing and softening food and (vii) for crushing food. Additional (viii) are connected to lungs to supplement respiration and heart is (ix) chambered. (B) Read the given passage and correct the errors wherever present. Amphibians are warm blooded animals. Their skull is monocondylic. The heart in amphibians is two chambered. Kidneys are metanephric. Their larval forms are ureotelic whereas adults are ammonotelic. Fertilisation is internal and twelve pairs of cranial nerves are present in them.

Assertion & reason In each of the following questions, a statement of Assertion (A) is given and a corresponding statement of Reason (R) is given just below it. Of the statements, mark the correct answer as : (a) if both A and R are true and R is the correct explanation of A (b) if both A and R are true but R is not the correct explanation of A (c) if A is true but R is false (d) if both A and R are false. 29. Assertion : True metamerism is present in annelids. Reason : The body of annelids is divided both externally as well as internally into a number of segments and external divisions correspond to internal division. 30. Assertion : Direct development is present in Hydra. Reason : In direct development, the young ones do not resemble the adults. 31. Assertion : Schizocoelom is found in echinoderms. Reason : The mesoderm arises from wall of embryonic gut as hollow outgrowths which form schizocolem. 32. Assertion : The inhalent pores in sponges are called ostia. Reason : Sponges have cellular level of organisation. 33. Assertion : Aschelminthes are called as pseudocoelomates. Reason : In Aschelminthes, mesoderm is present as scattered pouches in between ectoderm and endoderm. 34. Assertion : Cnidoblasts or stinging cells are present in coelenterates. Reason : Cnidoblasts are reserve totipotent cells which can be converted into any type of cell. 35. Assertion : In ctenophores locomotion takes place through comb plates. 42

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Reason : Comb plates are comb like ciliary plates present on the body of ctenophores. 36. Assertion : Adhesive organs, like suckers are present in flukes and hooks and suckers are present in tapeworms. Reason : Flukes and tapeworms are parasites and adhesive organs give them a firm grip on or in the host’s body. 37. Assertion : Amphids and phasmids are sense organs found in Phylum Aschelminthes. Reason : Amphids are glandulosensory in nature and phasmids are chemoreceptors. 38. Assertion : Blood vascular system in arthropods is of open type. Reason : In arthropods, blood does not flow in definite vessels but is present in irregular spaces called lacunae.

Figure Based Questions 39. Refer the given figure and answer the following questions.

(a) Identify the structures A, B, C and D. (b) Describe structure B. (c) In which subphylum, structure B is present throughout the life and extends from the anterior end to the posterior end of the body? Give one example of organism belonging to this group. (d) In which subphylum structure B is present only in the tail of larva and disappears in adult whereas structure A is replaced by dorsal ganglion in adult? Give one example of the organism belonging to this group. 40. Refer the given figure and answer the following questions.

(a) Identify the generic names of organisms A, B, C and D. (b) What is the mode of nutrition in organism A? Which structures supplement its mode of nutrition? (c) Describe various cells found in the epidermal layer of body wall of organism B. (d) To which Phylum organism C belongs? How does it defend itself from its enemies. (e) Describe the body cavity coelom and musculature found in organism D?

sOLUTIONs (b) (i) (ii) (iii) (iv) (v) (vi)

CHAPTER-1 : THE lIvING wORlD

1. 6. 11. 16. 18.

(c) 2. (d) 3. (b) 4. (b) 5. (a) (a) 7. (b) 8. (c) 9. (a) 10. (b) (c) 12. (a) 13 (b) 14. (b) 15. (b) True 17. True False : The word ‘species’ was introduced or defined by John Ray. 19. True 20. True 21. True 22. True 23. True 24. False : Natural History Museum is located in london. 25. True 26. A-(v), B-(i), C-(ii), D-(iii), E-(iv) 27. A-(i, v), B-(ii, vi), C-(iii,vii), D-(iv, viii), E-(ix, x) 28.(A) (i) irreversible (ii) cell division (iii) exclusive (iv) intussusception (v) anabolism (vi) catabolism (vii) Negative growth (B) According to the rules of binomial nomenclature each organism is given two names one name consisting of the two words, generic and specific. Two species belonging to same genus can cannot have similar specific names. The specific generic name is written first followed by generic specific name. Generic name begins with a small capital letter whereas specific name begins with a capital small letter. Scientific names are derived from Spanish latin language. 29. (c) 30. (a) 31. (a) 32. (b) 33. (a) 34. (c) 35. (d) 36. (d) 37. (b) 38. (b) 39. (a) A – Muscidae B – Solanales C – Monocotyledonae D – Felis catus (b) Convolvulaceae (c) Stomoxys (stable fly) 40. (a) A – A store house of collected plant specimens that are dried, pressed and preserved on sheets. B – Collection and maintenance of living plants for reference. C – Enclosed areas where animals are kept in open enclosures instead of cages. D – A place used for storage, preservation and exhibition of objects of natural history, art and antiquities. E – A dichotomic table of alternate characters known as couplet each character of couplet is called as lead.

41×29 Moscow ex-situ Andman and Nicobar Islands indented bracketed

CHAPTER-2 : BIOlOGICAl ClASSIFICATION

1. 6. 11. 16. 18.

(b) 2. (c) 3. (d) 4. (b) 5. (c) (b) 7. (d) 8. (d) 9. (c) 10. (d) (c) 12. (a) 13. (a) 14. (b) 15. (b) True 17. True False : The viral genome gets integrated with host DNA in lysogenic phase of reproductive cycle of virulent phages. 19. True 20. True 21. False : Zygote is the only diploid structure in the organisms having life cycle with zygotic meiosis. 22. True 23. True 24. True 25. False : Deuteromycetes are called imperfect fungi because they lack sexual reproduction. 26. A-(iv), B-(i), C-(ii), D-(v), E-(iii) 27. A-(i, viii), B-(vi, ix), C-(ii, v), D-(iii, iv), E-(vii, x) 28.(A) (i) terrestrial (ii) chlorophyll (iii) autotrophic (iv) cellulose (v) starch (vi) oil globules (vii) Motile (B) Sclerotia and rhizomorphs are the means of sexual vegetative reproduction in fungi. Rhizomorphs Sclerotia are perennating bodies made up of compact masses of hyphae whereas sclerotia rhizomorphs are rope like twisted subterranean masses of hyphae. Vegetative Asexual reproduction in fungi occurs through spores. The sexually produced spores are called mitospores, meiospores e.g., basidiospores, conidia ascospores , etc. Asexually produced spores are called meiospores mitospores, e.g., ascospores oidia, chlamydospores etc. 29. (b) 30. (c) 31. (b) 32. (a) 33. (d) 34. (b) 35. (b) 36. (d) 37. (a) 38. (c) 39. (a) : A – Zoospores B – Sporangiospores C – Chlamydospores D – Ascospores E – Basidiospores (b) (i) Zoospores (A) are motile spores that occur is some Phycomycetes, e.g. Phytophthora and Albugo. They bear 1-2 flagella anteriorly, posteriorly or laterally. (ii) Basidiospores (E) are nonmotile meiospores which are formed exogenously on short outgrowth of clubshaped structure called basidium. MT BIOLOGY

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(iii) Spore C(Chlamydospore) is found in Rhizopus and Mucor. (iv) Spore D(Ascospore) is characteristic of Class Ascomycetes. 40. (a):

39.

A – life cycle with zygotic meiosis B – life cycle with gametic meiosis

(b)

life cycle showing zygotic meiosis is found in dinoflagellates and cellular slime moulds. life cycle showing gametic meiosis is found in majority of protozoan protists, diatoms and acellular slime moulds.

(c)

Differences between life cycle with zygotic meiosis and life cycle with gametic meiosis are as follows. life cycle with zygotic meiosis

life cycle with gametic meiosis

1. Zygote is the only diploid All structures except structure in the life cycle. gametes are diploid. 2. The dominant individual in The dominant individual in the life cycle is haploid hence the life cycle is diploid hence the life cycle is haplontic. the life cycle is diplontic. 3. Meiosis takes place at the Meiosis occurs only at the time of zygote germination. time of gamete formation. CHAPTER-3 : PlANT kINGDOm

1. (d) 6. (c) 11. (c)

2. (d) 7. (d) 12. (c)

3. (a) 8. (a) 13. (b)

4. (b) 9. (d) 14. (c)

5. (b) 10. (d) 15. (c)

16. False : The plant body of mosses is always leafy. 17. True 18. False : In Funaria, the male receptacle is surrounded by rosette of divergent perigonial leaves. 19. True

20. True

23. True

24. True

21. True

22. True

25. False : Endosperm development takes place before fertilisation in gymnosperms, hence it is haploid. 26. A-(iv), B-(i), C-(v), D-(ii), E-(iii), F-(vi) 27. A-(i, vi), B-(iii, vii), C-(ii, iv), D-(v, viii), E-(ix, x) 28.

(B)

44

(A) : (i) – dorsiventral (ii) – thallose (iii) – foliose (iv) – midrib (v) – dichotomous (vi) – Elaters (vii) – peristome teeth Ferns are seed producing seedless vascular plants which inhabit dry humid areas. They constitute the smallest largest living group of primitive vascular plants. Ferns dominated the earth in permian carboniferous period. leaves are large and called ramenta fronds. Mature young MT BIOLOGY

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leaves show circinate ptyxis. younger parts of their stem, leaves and petiole possess hairs called fronds ramenta. 29. (b) 30. (a) 31. (a) 32. (a) 33. (b) 34. (c) 35. (d) 36. (c) 37. (b) 38. (d) (a) : In the given life cycle of Chalmydomonas, phase I represents asexual phase and phase II represents sexual phase. (b) X – Palmella stage Y – Akinete Z – Zoospores In palmella stage, a large number of near naked cells devoid of flagella lie inside a mass of mucilage. The stage develops in response to toxic chemicals and unfavourable water conditions. 40. (a) : P is oogamy. In oogamy there is a fusion of large food laden, non-flagellated female gamete and smaller motile male gamete. Q is anisogamy. In anisogamy, the fusing gametes are structurally similar but differ in size and behaviour. One of the two gamete is larger called macrogamete or female gamete and the other is smaller, termed microgamete or male gamete. R is isogamy. In isogamy, both the fusing gametes are morphologically and physiologically similar. They may be flagellated or non-flagellated. (b) S represents zygotic meiosis. (c) Chlamydomonas exhibits haplontic life cycle. This can be explained as follows: The plant body is unicellular and haploid. It gives rise to haploid gametes. Gametes fuse to produce diploid zygote. Meiosis occurs at the time of zygote germination. Zygote is the only diploid phase in its life cycle. CHAPTER-4 : ANImAl kINGDOm

1. (a) 6. (c) 11. (a)

2. (a) 7. (c) 12. (b)

3. (d) 8. (b) 13. (c)

4. (b) 9. (d) 14. (b)

5. (a) 10. (d) 15. (d)

16. False : Coelenterates have tissue level of body organisation. 17. True

18. True

19. False : Pseudometamerism is found in tapeworms whereas true metamerism is characteristic of Annelida. 20. True

21. True

22. True

23. True

24. False : Euplectella is commonly known as “The Venus’ flower basket” whereas Cliona is commonly known as ‘The Boring sponge’. 25. True 26. A-(ii), B-(i), C-(iv), D-(iii), E-(vi), F-(v) 27. A-(i, vi), B-(ii, v), C-(iii,vii), D-(iv,ix), E-(viii, x)

28.(A) (i) warm blooded (ii) forelimbs (iii) skin gland (iv) tail (v) beak (vi) crop (vii) gizzard (viii) air sacs (ix) four (B) Amphibians are warm cold blooded animals. Their skull is monocondylic dicondylic. The heart in amphibians is two three chambered. Kidneys are metanephric mesonephric. Their larval forms are ureotelic ammonotelic whereas adults are ammonotelic ureotelic. Fertilisation is internal external and twelve ten pairs of cranial nerves are present in them. 29. (a) 30. (c) 31. (d) 32. (b) 33. (a) 34. (c) 35. (b) 36. (a) 37. (c) 38. (a) 39. (a) A – Dorsal hollow nerve cord B – Notochord C – Pharyngeal gill slits D – Post anal part (tail) (b) Notochord (B) is a solid unjointed, stiff but flexible rodlike structure situated on the dorsal side between the dorsal hollow nerve cord and the alimentary canal. (c) In Subphylum Cephalochordata, structure B (notochord) is present throughout life and extends from the anterior end to the posterior end of the body. E.g. Branchiostoma. (d) In Subphylum urochordata, structure B (notochord) is present only in tail of the larva and disappears in adults. Structure A (Nerve cord) is found in larva but is replaced by dorsal ganglion in adult. E.g. Herdmania. 40. (a) A - Taenia B- Aurelia C - Octopus D - Palamneus

(b) Organism A (Taenia) shows parasitic mode of nutrition. Its body is divisible into scolex, neck and strobila. Scolex contains cone like rostellum at its top. Rostellum bears chitinous hooks in two circlets. On the middle part of scolex, 4 cup shaped suckers are present. Hooks and suckers are adhesive organs which help these parasites to attach firmly to the body of host from which they derive nutritiion. Hence, these structures supplement their parasitic mode of nutrition. (c) The epidermis of organism B consists of the following cells. (i) Epitheliomuscular cells. They provide protection and act as muscles. (ii) Cnidoblasts ( = stinging cells). A cnidoblast (also called nematoblast) has nematocyst (‘stinging organ’). The nematocyst consists of capsule, shaft and thread tube. The nematocysts are used for defence and offence. (iii) Interstitial cells. They are reserve cells and are called totipotent cells which can be converted into any type of cells, (iv) Nerve cells. They form a primitive nervous system. (v) Sensory cells. They are sensory in function. (d) Organism C (Octopus) belongs to Phylum Mollusca. It ejects inky fluid in water and forms a screen for defence from its enemies. (e) Body cavity is an extensive haemocoel filled with blood and surrounding the heart, alimentary canal, hepatopancreas, gonads, and other internal parts. Coelom is reduced to vestiges associated with reproductive system and certain glands. Musculature includes one pair of muscles in cephalothorax and eight pairs of dorso-ventral muscles in pre-adomen, running from dorsal to ventral surface of body, on either lateral side or body wall. 

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H GH

YIELD FACTS

Class XII

Sexual Reproduction in Flowering Plants-I –

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4

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formation and their subsequent fusion during fertilisation. Sexual reproduction is also called amphimixis.

4

• Sexual reproduction is the formation of new individuals through the gamete

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3 –

4

– BHU

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– J&K

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2 Kerala

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2012 2011

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arises just inside the corolla and the pistil or gynoecium (female reproductive organ), which lies in the centre of the flower.

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• The essential parts of a flower are the androecium (male reproductive organ), which

AMU

• The outermost whorl of floral parts is composed of sepals, collectively called the calyx. Petals, together called the corolla, form the next inner whorl. Sepals and petals constitute the non-essential parts of a flower.

AIIMS

receptacle - calyx, corolla, androecium and gynoecium.

4

• A complete flower consists of four whorls of floral appendages attached on the

2010

highly condensed internodes and leaves specialised variously to act as different floral parts or organs (like sepals, petals, stamens and carpels).

–

• Flower is considered to be a modified shoot (shoot of determinate growth) with

2009

reproductive phase. Flower is the most important part, which is concerned with sexual reproduction.

AIPMT/NEET

• In angiosperms, the main sporophytic plant body (2n) bears flowers during

Analysis of various PMTs from 2009-2014

developed root, stem, leaves and flowers makes the dominant phase while haploid gametophytes are microscopic, short lived and are dependent on sporophytes physically as well as physiologically. In their life cycle, sexually reproducing angiosperms exhibit most advanced, highly complex and longest sporophytic generation in the plant kingdom.

2013

• Life cycle in angiosperms is diplontic, in which the diploid sporophyte with well

• Each anther consists usually of two lobes connected

•

•

•

•

•

Homologies of flower parts • Carpel • Ovule

: Megasporophyll : Integumented

megasporangium • Embryo sac : Female gametophyte • Egg : Female gamete • Stamen : Microsporophyll • Pollen or pollen grain : Microspore • Germinating pollen grain : Male gametophyte

together by a sort of midrib known as the connective. Each lobe of the anther contains two pollen sacs or microsporangia; thus there are four pollen sacs or four microsporangia in each anther. Such anthers having 2 anther lobes and 4 microsporangia are called dithecous anthers or two celled anthers. However, at maturity, two microsporangia of an anther lobe get united by dissolution of partition wall between them. In some plants e.g., china rose, anther is having only single anther lobe and 2 microsporangia instead of 4. Such anthers are called monothecous anthers or one celled anthers. A rare case is Arceuthobium, where there is only one microsporangium per anther i.e., monosporangiate condition. The young anther is a homogeneous mass of meristematic cells surrounded by an epidermis. Soon groups of hypodermal cells in each of the four corners become distinguished from the surrounding cells by their large size, dense cytoplasm and prominent nuclei. These cells, which are arranged in plate-like or crescentshaped vertical rows, form the archesporium of the anther. The archesporial cells enlarge radially and divide periclinally resulting into outer primary parietal cells and inner primary sporogenous cells. The primary parietal cells undergo repeated periclinal and anticlinal divisions giving rise to 3-5 concentric layers which eventually from the anther wall. The primary sporogenous cells function as microspore mother cells.

Structure of microsporangium (pollen sac) • In a transverse section, a typical microsporangium appears

near circular in outline. It consists of two parts — outer wall and central homogenous sporogenous tissue. The four types of wall layers are: – Epidermis of single layer for protection. – Endothecium of single layer for dehiscence of anther. • Endothecium is the sub-epidermal layer of the anther

S ta m e n, m i c ro S p o r a n g i u m a n d pollen grain • Androecium consists of stamens as its units. The stamens

or microsporophylls are regarded as the male reproductive organs of the flower. • Each stamen consists of three parts - filament, anther and connective. • The filament is the slender stalk of the stamen, and the anther is the expanded head, borne by the filament.

wall. Mostly there is a single layer of endothecium, but sometimes, as in Coccinia indica, it is two layered. The cells of endothecium are radially elongated and attain their maximum development when pollen grains mature. The radial and inner tangential walls of these cells have characteristic fibrous thickening bands. Usually these bands are U-shaped or ring shaped, but in Melothria maderaspatana they occur in the form of two overlapping spirals. These bands are formed at the expense of the starch stored in endothecial cells. MT BIOLOGY

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pollens of an anther lobe are packed in a bag like structure called pollinium. In certain members of Family Orchidaceae, the pollinium is less compact and comprises smaller loose groups of pollen grains termed as massulae. • When 4 pollens of a tetrad do not separate and remain attached, they are known as compound pollen grains (e.g., Drimys, Drosera). • Polyspory is the occurrence of more than 4 spores in a pollen tetrad, e.g., Cuscuta reflexa. • The presence of fibrous bands, differential expansion

of inner and outer tangential walls and hygroscopic nature of endothecial cells play an important role in the dehiscence of anthers. – Middle layers 1-4 in number. – Tapetum, the innermost parietal layer with cells having dense cytoplasm and large nuclei. • Sporogenous tissue fills the whole interior of a microsporangium.

Functions of tapetum • Tapetum provides nourishment to developing microspores. It also secretes callase enzyme which dissolves callose substances by which 4 pollens of a pollen tetrad are united, hence separating microspores or pollens of a tetrad. • Tapetum secretes sporopollenin coated übisch bodies whose function is not clearly determined yet. Some consider them to assist in transport and deposition of sporopollenin at pollen wall while some consider them just to be a byproduct of sporopollenin. • Tapetum also secretes pollen kitt, the outermost oily, thick, sticky, coating of pollen grains, mainly composed of lipids and carotenoids. It is secreted in case of entomophilous pollen grains.

microsporogenesis • The process of formation of microspores from sporogenous •

•

• •

• 50

tissue is known as microsporogenesis. The sporogenous cells may directly function as microspore mother cells (also called pollen mother cells or PMCs) or they may undergo a few mitoses to add up to their number before entering meiosis. Each PMC, by a meiotic division, gives rise to a group of four haploid microspores. Aggregates of four microspores are referred to as microspore tetrads. In some cases, one microspore is formed from one pollen mother cell, e.g., Family Cyperaceae. Usually the arrangement of microspores in a tetrad is tetrahedral or isobilateral, however decussate, (e.g., Magnolia, Atriplex) linear (e.g., Halophila) and T-shaped (e.g., Aristolochia) tetrads are also found. In members of Asclepiadaceae and Orchidaceae, all the MT BIOLOGY

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Dehiscence of anther • Anther dehisces due to certain changes which take place in its wall layers at maturity. These changes are affected by environmental conditions. • The endothecial layer of the anther wall has fibrous bands on its inner tangential walls, except along the line of dehiscence. This region, which is marked by the presence of thin walled cells, is known as stomium. The hygroscopic nature and differential expansion of the tangential walls of the endothecium cells are mainly responsible for anther deshiscence. • Mostly, the stomium extends as a narrow strip throughout the length of the anther and hence the dehiscence is usually longitudinal. But in certain taxa the anther dehisces through a terminal valve (e.g., Berberidaceae), apical pore (e.g., Solanum, Polygala) or irregularly (e.g., Najas). • Sometimes the endothecial cells do not possess fibrous bands (e.g., Cassia). In such cases the anther dehisces due to unequal thickenings of its radial walls. In cleistogamous flowers, the endothecium is highly reduced and the pollen tube comes out through anther wall.

• Pollen grains are released from the anthers either at 2-celled stage or at 3-celled stage. They are released during

M-phase of cell division cycle (mitotic nuclear division stage) after going through the G1-phase (preparatory stage for DNA synthesis), S-phase (DNA synthesis stage) and G2-phase (preparatory stage for nuclear division). The 3-celled pollen grains are released during late M-phase, having two sperm nuclei. In the 2-celled pollen, the generative nucleus remains undivided and contains double the amount of DNA of sperm nucleus. Here the generative nucleus divides in the pollen tube.

Pollen grain • Pollen grain (microspore) is the first cell of the male

gametophyte. • Each pollen grain or microspore is a haploid, oval or rounded

structure. It has two layers: exine and intine. The exine appears first as a thin layer, but later becomes considerably thick and can be differentiated into two layers – ektexine (also called sexine) and endexine (also called nexine). The ektexine is further differentiated into a basal foot layer a middle bacula and an upper tectum. The bacula which consists of radially extended rods, forms various sculpturing pattern on the exine. • The exine is chiefly composed of sporopollenin.

Sporopollenin is absent in the pollen grains of Zostera.

• The thin areas of the exine are called germ pores or

germ slits. Inner layer called intine is thin, smooth and is composed of pectocellulose. • The cytoplasm of pollen grain contains dictyosomes,

mitochondria and endoplasmic reticulum. Pollen grains are densely cytoplasmic as long as they are in tetrads. But soon after their release from the tetrad, they undergo considerable enlargement and as a result their cytoplasm becomes highly vacuolated.

Sporopollenin is considered to be the oxidative polymer of carotenoids and/or carotenoid esters. It is one of the most resistant organic materials. It is not degraded by any enzyme. It is not affected by high temperature, strong acid or strong alkali. Because of the sporopollenin, pollen grains are well preserved as fossils.

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development of male gametophyte • The development of the male gametophyte is more or less • •

•

•

•

•

uniform in all flowering plants. Development of male gametophyte is precocious that is it begins inside the microsporangium or pollen sac. The size of the nucleus increases and it divides mitotically to produce a bigger vegetative or tube cell and a smaller generative cell. The tube cell has a vacuolate cytoplasm which is rich in food reserve and cell organelles. Its nucleus becomes large and irregular. The generative cell undergoes a lot of change in shape during pollen development. Its cytoplasm is highly reduced but contains the usual cell organelles along with a prominent nucleus. Male gametes are formed by a mitotic division in the generative cell. This may take place after the release of pollen from the anther or while the pollen are still confined to the anther. Thus, in the former condition the pollen are shed at the 2-celled stage and in the latter at the 3-celled stage. After reaching the stigma, the intine grows out through a germ pore into slender pollen tube.

which is single or many chambered, is termed ovary. • The ovary contains one or more round or oval, egg-like

bodies, known as the ovules which are attached to the placenta. Each ovule contains a large oval cell known as the embryo sac. The ovary gives rise to the fruit and ovules give rise to the seeds after fertilisation.

Structure of ovule • An ovule or integumented megasporangium develops

•

• •

• •

•

from the base or the inner surface of the ovary. It is small, generally an oval structure and consists chiefly of a central body of tissue, the nucellus and one or two integuments. Each ovule is attached to the placenta by a small stalk called the funiculus. The ovule lacking the funicle is called sessile. The place of attachment of the funiculus with the main body of the ovule is called the hilum. In an inverted ovule, the funicle fuses with the main body of the ovule, forming a sort of ridge, known as the raphe. The upper end of the raphe which is the junction of the integuments and the nucellus is called the chalaza. The nucellus, a mass of parenchymatous cells, is equivalent to megasporangium. On the basis of quantity of nucellus, ovules are of two types: tenuinucellate (nucellus is very thin) and crassinucellate (nucellus is massive). Ovules having single integument are called unitegmic ovule. It is common in Gamopetalae. Ovules having 2 integuments are called bitegmic ovule, e.g., members of Polypetalae and monocots. When nucellus is not surrounded by integuments, the ovule is called ategmic, e.g., Santalum album, Loranthus. Supernumerary integuments, i.e., more than two

piStil, ovule and embryo Sac • Gynoecium is female reproductive whorl of the flower. It is

• •

•

• 52

composed of one or more carpels or pistils. The carpels are modified leaves which bear the ovules, and also called the megasporophylls. Each carpel consists of three parts, i.e., stigma, style and ovary. The stigma is the terminal end of the style upon which the pollen grains fall, and is generally knob-like and sticky. The style is the slender projection of the ovary and bears stigma at its terminal end. The surface of the style may be smooth or covered with hairs. In many cases, these hairs collect the pollen grains. The swollen basal part of the carpel MT BIOLOGY

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integuments have also been reported in some taxa. In Asphodelus and Trianthema, a third integument, called aril, arises from the base of the ovule and it covers completely the other two integuments. In many Euphorbiaceae, an outgrowth arises from the tip of the outer integument which turns backward and partially envelops the ovules. This outgrowth is called caruncle. • A small opening is left at the apex of the integuments; this is called the micropyle. When there are two integuments then the inner integument is formed first followed by the formation of the outer integument. • In the basal part of the nucellus, in between the embryo sac and vascular bundles, there is a group of cells with lignified and suberized walls, which is called

•

•

•

•

hypostase. These cells usually have poor cytoplasmic contents and deformed nuclei, but occasionally they may have dense cytoplasm and thin walls like glandular cells. Hypostase is known to occur in many diverse families like Apiaceae, Loranthaceae, Euphorbiaceae, Liliaceae and Elaeagnaceae. In some taxa such as Costalia, Costus, Rheum and Agave a few modified cells of the nucellus are present at the top of the embryo sac and these cells are referred to as epistase. A large oval cell lying embedded in the nucellus towards the micropylar end is the embryo sac or female gametophyte. This makes the most important part of the mature ovule. It is the embryo sac, which bears the embryo later on.

integuments (i.e., body of ovule) are at right angle to stalk or funiculus, e.g., in Primulaceae and Ranunculaceae. • In campylotropous ovule, the body of the ovule gets curved and micropyle is directed downwards. Further, micropyle is not in line with chalaza and funicle lies at right angles to chalaza, e.g., in Capparidaceae, Chenopodiaceae, etc. • In amphitropous ovule, curvature is observed both in the body of ovule and embryo sac. The embryo sac assumes horse shoe-shape, e.g., in Papaveraceae, Alismataceae and Butomaceae, etc. • Circinotropous is found in family cactaceae, e.g., Opuntia. Here the ovule is straight first, later on due to more growth on one side the ovule gets inverted, but this unilateral growth still continues till the ovule becomes straight again. In this manner, the funiculus takes a complete round around the body of ovule.

• Any ovular structure which directs the growth of pollen tube

towards micropyle of ovule is called obturator. It acts as a type of bridge for pollen tube. Obturator may originate from funiculus or placenta.

types of ovule • Depending upon position of micropyle in relation to chalaza

• •

•

•

and funiculus, 6 types of ovule have been recognised in angiosperms. These are orthotropous, anatropous, hemianatropous, campylotropous, amphitropous and circinotropous. Orthotropous or atropous or straight is the most primitive and simplest type of ovule in angiosperms. This is erect (i.e., micropyle at upper end) and here micropyle, chalaza and funiculus lie in a same straight line, e.g., in Polygonaceae and Piperaceae. Anatropous or inverted is the most common type of ovule found in angiosperms (i.e., in 82% of angiosperm families). Here, body of the ovule gets inverted and micropyle is on lower side. Further micropyle and funiculus lie side by side and micropyle is close to hilum. In hemianatropous or hemitropous ovule, nucellus and

megasporogenesis • Formation of megaspore (n) from megaspore mother cell

(2n) inside the ovule is called megasporogenesis. • In the hypodermal region of nucellus towards the micropylar end develops a primary archesporial cell. • The primary archesporial cell divides to form outer parietal cell and inner sporogenous cell. The sporogenous cell functions as megaspore mother cell (MMC), which undergoes reduction division to form 4 haploid megaspores. • Only one megaspore remains functional and the other 3 degenerate. Only the functional megaspore develops into MT BIOLOGY

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female gametophyte. This type of embryo sac is called monosporic.

development of female gametophyte • The functional megaspore is the first cell of female •

•

•

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• •

•

•

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gametophyte or embryo sac. The nucleus of megaspore undergoes free nuclear mitotic divisions to form 8 nuclei and gives rise to embryo sac or female gametophyte, the process is called megagametogenesis. Out of 8 nuclei, 4 nuclei are arranged at each pole. One nucleus from each pole migrates to the centre to form two polar nuclei which further fuse to form a diploid or secondary nucleus. Three nuclei at the base of embryo sac form antipodal cells. The remaining 3 nuclei at the micropylar end get surrounded by cytoplasm and are called egg apparatus. Thus a typical angiosperm embryo sac, at maturity, though 8-nucleate is 7 celled with 3 micropylar, 3 chalazal and one central cell. It is formed by one meiosis and three mitosis. In egg apparatus, one cell is larger and is called the egg or oosphere and the other two are called synergids. Synergids are short-lived (one of them degenerates long before fertilisation and second after entry of pollen tube into embryo sac). These synergids help: – In growth of pollen tube towards egg by secreting chemotropically active substances. – In nutrition of embryo sac by absorption and transport of food from nucellus through their filiform apparatus. Filiform apparatus in the form of finger like projections from cell wall is present in upper part of each synergid. MT BIOLOGY

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•

•

•

•

The filiform apparatus is useful for the absorption and transportation of materials from the nucellus to the embryo sac. Hook like structures help in easy penetration of pollen tube and liberation of male gamete from the pollen tube. Egg is the constant feature of embryo sac. It fuses with one male gamete to form zygote (syngamy) and hence embryo. The central cell consists of two polar nuclei. Two polar nuclei fuse to form single diploid secondary nucleus or definitive nucleus. The typical 8 nucleate 7 celled embryo sac, found in 80% flowering plants is called Polygonum type of embryo sac. Oenothera type of monosporic embryo sac develops from single functional megaspore of micropylar end (not chalazal). Oenothera embryo sac is four nucleated having egg apparatus and a single polar nucleus in centre. Antipodals are absent. This type is characteristic of the Family Onagraceae. Tetrasporic embryo sac is of different types viz. Peperomea, Penaea, Fritillaria, Plumbagella, Plumbago, Drusa and Adoxa.

pollination • The transfer of pollen grains from anther to the stigma is

called pollination. • Pollination in angiosperms generally takes place at 2-celled stage (rarely 3-celled stage) of microspores or pollen, i.e., pollen having vegetative cell and generative cell. • If the pollen grains are transferred to the micropyle of the ovule directly, the pollination is called direct pollination, e.g., gymnosperms. Since the ovules are enclosed in the ovary in angiosperms, the pollination is called indirect pollination. • Pollination is of two types – self pollination and cross pollination.

Self pollination • The transfer of pollen grains from anther to stigma of

• •

• •

same flower or genetically similar flower is called self pollination. Self pollination is of two types – autogamy and geitonogamy. Autogamy is the transfer of pollen grains from anther to stigma of same flower. Geitonogamy is the transfer of pollen grains from the anther of one flower to the stigma of another flower present in the same inflorescence or in the same plant. Geitonogamy occurs between bisexual flowers or unisexual flowers of the same plant. Geitonogamy is genetically equivalent to self pollination but ecologically it is cross pollination.

1. 2. 3.

• Flowers show many contrivances (devices) to ensure self

pollination such as: – In some plant, flowers are bisexual and both sexes mature at the same time (homogamy). – In some cases, flowers are bisexual and cleistogamous, i.e., remain closed (e.g., Commelina benghalensis). – In some cases, pollination occurs in bud condition before the opening (anthesis) of flower, (e.g., pea, wheat, etc.) Advantages of self pollination • The advantages of self pollination are: – It maintains the parental characters or purity of the race indefinitely. – Self pollination is used to maintain pure lines for hybridisation experiments. – The plant does not need to produce large number of pollen grains. – Flowers need not to develop devices for attracting insect pollinators. – It ensures seed production. – Self pollination eliminates some bad recessive characters.

Disadvantages of self pollination • The disadvantages of self pollination are: – New useful characters are seldom introduced. – Vigour and vitality of the race decreases with prolonged self pollination. – Immunity to diseases decreases. – Variability and hence adaptability to changed environment is reduced.

cross pollination • Cross pollination (or allogamy or xenogamy) is the

process when pollens are transferred from anther of one flower to stigma of flower of a genetically different plant of same species. • Dichogamy ( flowers maturing at different times), dicliny or unisexuality, herkogamy (presence of natural and physical barrier between androecium and gynoecium), heterostyly and self sterility are the main reasons or adaptations for cross pollination in bisexual flowers.

What are the functions of tapetum? For its pollination, the orchid Ophrys speculum has picked up one of the most selective attraction. How is this insect-plant relationship beneficial only to the plant? How do synergids help in the nutrition of embryo sac? MT BIOLOGY

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Advantages of cross pollination • The advantages for cross pollination are: – Cross pollination introduces genetic recombinations and hence variations in the progeny. – Cross pollination increases the adaptability of the offspring towards changes in the environment. – The plants produced are usually larger and the offspring have characters better than the parents due to the phenomenon of hybrid vigour. – The plants produced are more resistant to diseases. – New and more useful varieties can be produced through cross pollination. – The defective characters of the race are eliminated and replaced by better characters. Disadvantages of cross pollination • The disadvantages of cross pollination are: – It is highly wasteful because plants have to produce a large number of pollen grains and other accessory structures in order to suit the various pollinating agencies. – Some undesirable characters may creep in the race. – The very good characters of the race are likely to be spoiled. – As external agency is involved so the chance factor is always there.

agents of pollination • The transfer of pollen grains from plant to plant in cross

pollination takes place through biotic agencies (living agencies) or through abiotic agencies (non-living agencies).

Anemophily • The pollination taking place by means of wind is known as anemophily. E.g., Zea mays (maize), grasses, mulberry, date palm, Salix, Cannabis etc. • Main features of wind pollinated flowers are : – Non-essential whorls such as calyx, corolla, bracts and bracteoles are not showy. – Flowers are devoid of scent and nectar. 56

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– In case of unisexual flowers, the male flowers are more

– – –

– –

in number than female flowers and in case of bisexual flowers, the stamens are generally numerous. Both the stigmas and anthers are exserted. Plants produce a very large quantity of dusty pollen grains. Pollen grains are dry, very small sized, non-sticky and unwettable, so that they can be carried by wind to long distances. Stigma is hairy, feathery (grasses) or branched to catch the wind borne pollens. Anemophily is associated with reduction in the number of ovules per ovary. Biological justification for this reduction is that chances for windborne pollen reaching the right stigma are remote. If the flowers of windpollinated plants were to produce many ovules most of them would have remained unfertilized. In grasses there is just one ovule per ovary.

Hydrophily • Pollination which occurs with the help of water is called hydrophily. • Main features of water pollinated flowers are : – Inconspicuous and small flowers. – Odour, nectar and colour is absent in flowers. – Flower whorls, if present then coated by wax. – Pollen grains are small, light weighted, non-sticky and coated by wax. – Stigma is unwettable but sticky. • Hydrophily is of two types— hypohydrophily and epihydrophily. • Hypohydrophily occurs below the surface of water, e.g., Ceratophyllum, Najas, Zostera. • Zostera is submerged marine perennial plant where the pollens are exceptionally long (upto 250 mm) and needlelike. They look more like pollen tubes. The specific gravity of these pollens is almost the same as that of sea water. Consequently, they can freely float in water at any depth. The stigma is also very long in this plant. If a pollen comes in contact with the stigma, it coils around the latter. • Epihydrophily takes place over the surface of water, e.g., Potamogeton, Vallisneria, Myriophyllum, Ruppia maritima. • Vallisneria (ribbon weed) is a classic example of this type. It is a submerged dioecious plant. The flowers are borne under water. Upon attaining maturity the male flowers get detached from the parent plant and float on the surface of water. The anthers project beyond the margins of the sepals. • The pistillate flowers also develop under water. At the time of pollination they are brought to the surface by thin, long

and slender stalk. Due to its weight a small cup-shaped depression is formed around the female flower. If male flowers, floating on the surface, come close to the female flowers they tumble down into the depression. • The anthers strike the exposed stigma, and the pollen mass is transferred to it. After pollination the stalk of the pistillate flower undergoes spiral torsion. The coils draw closer and tighten, bringing the pollinated flowers under water once again. The fruits mature in submerged condition.

Entomophily • Pollination by insects is called entomophily. Many insects such as bees, wasps, ants, hover bees, moths, butterflies, grasshopper, locusts, beetles, dragon flies, bugs, thrips are involved in pollination. • Main features of insect-pollinated flowers are : – Nectar is produced by nectar glands of flower which attracts the pollinators for feeding. – Some flowers produce edible pollen grains which attract the pollinators to visit the flowers e.g., Rosa, Clematis, Magnolia. – Flowers are fragrant and emit scent and odour e.g., Jasminum, Cestrum etc. – Flowers are bright coloured, they have coloured leaves, petals, sepals, stamens or sometimes stigma, e.g., leaves in Euphorbia pulcherrima, bracts in Bougainvillea. – Small flowers occur in groups and thus, become more conspicuous. – Stigma also secretes some exudates which make stigma sticky. This sticky stigma can get pollens easily. – Th e p o l l e n g r a i n s a r e spiny, heavy and surrounded by a yellow oily sticky substance called pollenkit. 57



– To sustain animal visits, the flowers have to provide

rewards to the animals.Nectar and pollen grains are the usual floral rewards. In some species floral rewards are in providing safe places to lay eggs; e.g., Yucca, Amorphophallus. • Insect pollinated plants show different mechanisms for pollination such as: – In Salvia (sage plant), a member of family labiatae, pollination occurs by bees and there is a special mechanism called “turn pipe mechanism” or “lever mechanism” of pollination. – ‘ Fly trap mechanism’ of pollination occurs in Aristolochia. Flies are attracted by foul-rotten tobacco like odour. – ‘Trap door mechanism’ of pollination occurs in Ficus species (having hypanthodium inflorescence). – In orchid ( Ophrys speculum) pollination occurs by act of pseudocopulation by the wasp called Colpa. Appearance and odour of Ophrys flower is similar to female wasp and hence male wasps are mistaken and they land on Ophrys flowers to perform act of pseudocopulation and thus pollination takes place. This plantinsect relationship is useful only to plant. – The plant Yucca has developed an obligate symbiotic relationship with the moth Tageticula, both the species, moth and the plant, cannot complete their life cycles without each other. The moth deposits its eggs in the locule of the ovary and the flower, in turn, gets pollinated by the moth. The larvae of the moth come out of the eggs as the seeds starts developing.

Ornithophily • Pollination of flowers by birds is called ornithophily. Ornithophilous flowers have tubular (Nicotiana glauca), cup-shaped (Callistemon) or urn-shaped (some members of Ericaceae) corollas. • Ornithophilous flowers are large sized, brightly coloured, usually odourless and they produce a large amount of mucilagenous nectar for drinking by birds. E.g., Strelitzia reginae is pollinated by sun birds, Bignonia by humming birds, Aloe vera by sun bird and Salmelia by crow and mainas. MT BIOLOGY

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• Humming birds are the most common group of flower

three categories depending upon the benefits (rewards) which they provide to the pollinators :

Malacophily • Pollination by snails is called malacophily. This type of pollination is seen in some plants such as Lemna, Aroids, etc. Myrmecophily • It is the pollination of flowers by means of ants, e.g., some members of family Rubiaceae.

– Food providing flowers, e.g., Salvia and bees,

Significance of pollination

visiting birds in America. Honey creepers are common pollinators in Africa and Asia. Humming birds are mostly attracted to bright red coloured, odourless flowers. • Flowers pollinated by insects/birds can be grouped into

humming birds and Bignonia, sun birds and Strelitzia. – Sex providing flowers, e.g., Ophrys and Colpa

wasp. – Nursery providing flowers, e.g., Yucca and yucca

moth, fig and wasp.

Chiropterophily • Pollination of flowers by means of bats is called

chiropterophily. Bat pollinated flowers are dull-coloured with strong fermenting or fruity smell, abundant nectar and pollen grains. Examples of chiropterophilous plants are Kigelia, Adansonia, etc.

– Pollination is a means of taking the male gametophyte

for its growth near the female gametophyte. – Pollen-pistil interaction determines the suitability

of pollen for carrying out the process of sexual reproduction. – It has freed the seed plants from the dependence on external water during fertilisation. – It can be manipulated to produce pure lines as well as desired varieties. • After successful pollination, pollen germinates on stigma followed by the process of fertilisation. Fertilisation eventually leads to development of seeds containing embryo.

pollen storage • Some of the methods currently used for pollen storage are as follows : – Dry and Cold storage : Sub-freezing temperatures (–5°C to – 10°C) and low relative humidty (25 to 50%) have

generally proved optimum for storing pollen in viable condition. – Cryogenic storage: Application of cryogenic technique (storage in liquid nitrogen, at –196°C) to preserve pollen viability

for prolonged duration has been found suitable for several economically important crops. At –196°C pollen undergo negligible metabolic changes in terms of physiological and biochemical processes which otherwise might render them inviable. This method has also been recommended for convenient and economical storage and transport of germplasm. – Organic solvents : Acetone, benzene, ethanol, ether, chloroform and phenol, are generally regarded as toxic to organisms. However, it has been demonstrated beyond doubt that pollen grains kept in these organic solvent can germinate in vitro and even effect fertilisation. (Iwanami et al, 1988). • Some of the practical applications of pollen storage are: – To hybridise plants that flower at different times and locations or show non-synchronous flowering. – To provide a constant supply of short-lived (recalcitrant) pollen. – To facilitate supplementary pollination for improving yield. – To eliminate the need to grow male lines continuously in breeding programmes. – To ensure the availability of pollen throughout the year without using nurseries or artificial climate growth rooms. – To study pollen allergens and the mechanism of self-incompatibility. – Long-term germplasm storage, especially of unique genotypes.

4. 5. 6. 58

“Geitonogamy is genetically equivalent to self pollination but ecologically it is cross pollination”. Justify this statement. Give two characteristic features of entomophilous flowers. How is malacophily different from myrmecophily? MT BIOLOGY

TODAY | JULY ‘15

1. The device that guides the pollen tube in the cavity of ovary is (a) obturator (b) transmitting tissue (c) placenta (d) synergids. 2. Which one is the female gamete in embryo sac? (a) Synergid (b) Antipodal cell (c) Oosphere (d) Central cell 3. Embryo sac represents (a) megaspore (c) megasporophyll

(b) megagametophyte (d) megagamete.

4. What does the filiform apparatus do at the entrance into ovule? (a) It brings about opening of the pollen tube. (b) It guides pollen tube from a synergid to egg. (c) It helps in the entry of pollen tube into a synergid. (d) It prevents entry of more than one pollen tube into the embryo sac.

11. The sequence of development of embryo sac is (a) archesporium → megaspore → megasporangium → embryo sac (b) archesporium → megaspore → megaspore mother cell → embryo sac (c) archesporium → megaspore mother cell → megaspore → embryo sac (d) megaspore mother cell → archesporium → megaspore → embryo sac. 12. A typical angiosperm embryo sac at maturity is eight nucleate and (a) single celled (b) four celled (c) seven celled (d) eight celled. 13. Given figure represents the four wall layers (P, Q, R and S) of an anther. Cells of which of the following layers develop fibrous thickenings of a-cellulose on the inner and radial walls, and help in the process of dehiscence?

5. If there are 4 pollen mother cells in an anther, what will be the number of pollen grains? (a) 16 (b) 12 (c) 8 (d) 4 6. An ovule in which the nucellus and embryo sac lie at right angle to the funicle is (a) hemitropous (b) campylotropous (c) anatropous (d) orthotropous. 7. Male gametes in angiosperms are formed by the division of (a) generative cell (b) vegetative cell (c) microspore mother cell (d) microspore. 8. In flowering plants, a mature male gametophyte is derived from a pollen mother cell by (a) two mitotic divisions (b) one meiotic and two mitotic divisions (c) three mitotic divisions (d) a single meiotic division. 9. A plant has 24 chromosomes in “microspore mother cell”. The number of chromosomes in its endosperm will be (a) 36 (b) 24 (c) 12 (d) 48. 10. Pollen grains are shed at which stage? (a) 2 celled (b) 3 celled (c) Usually at 2-celled, but sometimes at 3-celled (d) Single celled

(a) P (c) R





(b) Q (d) S

14. The egg apparatus of angiosperm comprises (a) an egg cell and two antipodals (b) an egg cell and two synergids (c) an egg cell and two polar nuclei (d) an egg cell and the central cell. 15. Exine of pollen grain is made up of a highly resistant fatty substance called (a) pectocellulose (b) lignocellulose (c) sporopollenin (d) pollen kit. 16. Which of the following statements about sporopollenin is false ? (a) Exine is made up of sporopollenin. (b) Sporopollenin is one of the most resistant organic materials. (c) Exine has apertures called germ pores where sporopollenin is present. (d) Sporopollenin can withstand high temperatures and strong acids. MT BIOLOGY

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17. In angiosperms, functional megaspore develops into (a) embryo sac (b) ovule (c) endosperm (d) pollen sac. 18. Pollination by the agency of snails is known as (a) ornithophily (b) chiropterophily (c) entomophily (d) malacophily. 19. One advantage of cleistogamy is (a) it leads to greater genetic diversity (b) seed dispersal is more efficient and widespread (c) seed set is not dependent on pollinators (d) each visit of a pollinator results in transfer of hundreds of pollen grains.

26. Even in absence of pollinating agents, seed-setting is assured in (a) Commellina (b) Zostera (c) Salvia (d) fig. 27. Which one of the following pairs of plant structures has haploid number of chromosomes? (a) Nucellus and antipodal cells (b) Egg nucleus and secondary nucleus (c) Megaspore mother cell and antipodal cells (d) Egg cell and antipodal cells 28. Study the given figure of an embryo sac and select the correct option regarding A, B, C and D.

20. Chiropterophily means (a) pollination by snails (b) pollination by bats (c) pollination by wind (d) pollination by insects.

21. Wind pollinated flowers are (a) small, brightly coloured, producing few pollen grains (b) small, producing large number of dry pollen grains (c) large, producing abundant nectar and pollen grains (d) small, producing nectar and dry pollen grains.

(a) Cells labelled as ‘A’ are ususally present at micropylar end. (b) Cells labelled as ‘C’ and ‘D’ are usually present at chalazal end. (c) ‘B’ represents polar nuclei which may fuse to form a diploid secondary nucleus. (d) Cells labelled as ‘A’ are diploid cells.

22. The type of pollination involving transfer of pollen grains from anther to the stigma of the same flower is known as (a) geitonogamy (b) xenogamy (c) autogamy (d) apogamy. 23. The type of pollination that brings genetically different types of pollen grain to the stigma of a plant is called (a) xenogamy (b) geitonogamy (c) chasmogamy (d) autogamy. 24. Maize and grasses are generally pollinated by (a) bees (b) butterflies (c) birds (d) wind. 25. Match the items in Column I with those in Column II and select the correct answer from the codes given below. Column I Column II 1. Funicle A. Small opening of ovule 2. Integuments B. Stalk of ovule 3. Chalaza C. Protective envelopes of ovule 4. Hilum D. Junction part of ovule and stalk 5. Micropyle E. Basal part of the ovule (a) 1-B; 2-C; 3-E; 4-D; 5-A (b) 1-A; 2-C; 3-B; 4-D; 5-E (c) 1-B; 2-C; 3-A; 4-D; 5-E (d) 1-B; 2-D; 3-E; 4-A; 5-C 60

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29. Select the incorrect statement regarding sexual reproduction in flowering plants. (a) Pollen grain is the first cell of male gametophyte. (b) An ovule represents integumented megasporangium. (c) Nucellus of the ovule is a diploid structure. (d) Stamen is equivalent to megasporophyll. 30. Microsporogenesis is the (a) formation of megaspore (b) formation of pollen grain (c) development of male gametophyte (d) development of female gametophyte.

Answer 1. 6. 11. 16. 21. 26.

(a) (a) (c) (c) (b) (a)

2. (c) 7. (a) 12. (c) 17. (a) 22. (c) 27. (d)

3. 8. 13. 18. 23. 28.

(b) (b) (b) (d) (a) (c)

Key 4. 9. 14. 19. 24. 29.

(b) (a) (b) (c) (d) (d)

5. (a) 10. (c) 15. (c) 20. (b) 25. (a) 30. (b) 

COMEDK 1. Troublesome American water weed found in India is (a) Vallisneria (b) Eichhornia (c) Hydrilla (d) Lemna. 2. Endangered plant species are conserved through (a) herbarium (b) cryopreservation (c) gene bank (d) tissue culture. 3. Which of the following regions of our country are known for their rich biodiversity? (a) Western Ghats and Eastern Himalayas (b) Western Ghats and Deccan Plateau (c) Eastern Himalayas and Gangetic Plain (d) Trans Himalayas and Deccan Peninsula 4. The worst threat to wildlife is by (a) habitat destruction (b) hunting (c) overgrazing (d) exotic species. 5. Breeding place of Flamingo (Hansawar) in India is (a) Sambhar lake (b) Chilka lake (c) Rann of Kutch (d) Ghana Vihar. 6. A woman with blood group “O” has a child with blood group“O”. If she claims a friend of hers with blood group ‘A’ as father of the child, the genotype of the father should be (a) I OI O (b) I AI B (c) I AI O (d) I BI O. 7. Gene sequencing has been done for a number of organisms. Among the four organisms given below choose the organism not sequenced. (a) Drosophila melanogaster (b) Saccharomyces (c) Oryza sativa (d) Solanum tuberosum 8. Stanley Miller and urey proved abiotic origin of life by using one of the following sets of chemicals in the lab. (a) CH4, H2, NH3 (b) CH4, H2, NH3, O2 (c) CH4 and NH3 (d) CH4, H2, O2

9. Distance between the genes and percentage of recombination show (a) a direct relationship (b) an inverse relationship (c) a parallel relationship (d) no relationship. 10. Fossils act as evidences of organic evolution. Which one of these features does not justify the feature of fossils? (a) They are remains of hard parts of life forms that existed in the past. (b) They are the remains of decayed and decomposed body parts. (c) Fossils present in the lower strata of the earth are older than those present in the upper strata. (d) Study of fossils in different sedimentary layers indicates the geological period in which they existed. 11. Development of hybrid varieties of plants and better milk yielding varieties of cows is an example of (a) natural selection (b) artificial selection (c) mutation (d) divergent evolution. 12. According to the theory of spontaneous generation (a) life originated from outer space (b) life originated from decaying and rotting matter like straw, mud etc. (c) life came from pre-existing life (d) life came from both living and non-living matter. 13. The chromosomal pattern of Klinefelter’s syndrome is (a) XXX (b) XXy (c) XO (d) Xyy. 14. The most important component of oral contraceptive pill is (a) progesterone (b) growth hormone (c) thyroxine (d) luteinizing hormone. 15. Papaya is a dioecious plant. This condition prevents (a) both autogamy and geitonogamy (b) only autogamy (c) only xenogamy (d) geitonogamy. MT BIOLOGY

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61

16. Given below are four methods (A-D) and their modes of action (i-iv) in achieving contraception. Select their correct matching from the four options that follow: Method

Mode of Action

A. The pill

(i)

Prevents sperms reaching cervix

B. Condom

(ii)

Prevents implantation

C. Vasectomy

(iii) Prevents ovulation

D. Copper T

(iv) Semen contains no sperms

(a) (b) (c) (d)

25. Identify A, B, C and D in the given diagram.

A-(ii), B-(iii), C-(i), D-(iv) A-(iii), B-(i), C-(iv), D-(ii) A-(iii), B-(iv), C-(i), D-(ii) A-(iv), B-(i), C-(ii), D-(iii)

17. There are various types of reproduction, the type of reproduction adopted by an organism depends on (a) the habitat and morphology of organism (b) morphology of organism (c) morphology and physiology of organism (d) the organism’s habitat, physiology and genetic make up. 18. The tissue that nourishes the developing pollen grains is (a) tapetum (b) endothecium (c) endothelium (d) middle layer. 19. A few plants exhibit unusual flowering phenomenon, which of them flower only once in their life time, generally after 50-100 years and produce large number of fruits? (a) Strobilanthus kunthiana (b) Bamboo (c) Calistemon linearis (d) Cymbopogon reptocus 20. The girth or diameter of the stem increases due to the activity of the following. (a) Apical meristems (b) Intercalary meristems (c) lateral meristems (d) Parenchyma cells 21. leafy green stems of limited growth modified to perform photosynthesis are called as (a) phyllode (b) phylloclade (c) cladode (d) foliar stipules. 22. Intercalated discs occur (a) between neurons (b) between cardiac muscle fibres (c) at the junction of muscle and nerve cells (d) in stripe muscles. 23. What is the advantage in clinical use of humulin (human insulin produced through rDNA technique) over use of conventional ox or pig insulin? (a) It does not cause immunological problems. (b) It is cheaper for the patient. (c) It is produced by E.coli in our own intestine. (d) There is no advantage. 62

24. One of the advantages of developing transgenic mice is that it is very useful (a) to study vaccine safety (b) in producing new varieties of mice (c) in developing a show piece example (d) in gene targeting.

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(a) (b) (c) (d)

A-ori, B-ampR, C-tetR, D-Hind III A-Hind III, B-tetR, C-ampR, D-ori A-ampR, B-tetR, C-Hind III, D-ori A-tetR, B-Hind III, C-ori, D-ampR

26. The biological product created by the introduction of portions of DNA which codes for a-1 antitrypsin, is used to treat (a) emphysema (b) asthma (c) bronchitis (d) cystic fibrosis. 27. What is true of Bt toxin? (a) The concerned bacillus has anti toxin. (b) Bt protein exists as active toxin in the bacillus. (c) The inactive protein gets converted into active form in the insect gut. (d) Activate toxin enters ovaries of pest and sterilize them. 28. Which one of these is not a tool of recombinant DNA technology? (a) Restriction enzyme (b) Vector (c) Polymerase enzyme (d) Introns 29. The breeding of the unrelated animals which may be between individuals of the same breed, (but having no common ancestors), or between different breeds or different species is known as (a) interspecific hybridisation (b) out-breeding (c) out-crossing (d) cross-breeding. 30. Resistance to yellow mosaic virus in Abelmoschus esculentus was transferred from a wild species and resulted in a new variety called (a) Sehore (b) Raphanus sativus (c) Parbhani kranti (d) Musa pudica.

31. The Plasmodium initially multiplies within the liver cells and then attacks the red blood cells, resulting in their rupture. The rupture of RBCs is associated with release of a toxic substance (a) hirudin (b) heparin (c) heptoin (d) haemozoin. 32. When are interferons secreted in the body? (a) When antibody reacts with antigen in our body. (b) When serotonin becomes active. (c) When lymphocytes become active. (d) When the cells are infected by virus. 33. Dr. Alexander Fleming observed inhibition zone around a blue mould in a contaminated Staphylococcus culture Petri plate. This led to the discovery of (a) antibiotics (b) antitoxins (c) antibodies (d) antigens. 34. MOET is a programme that is used to increase (a) herd size (b) disease resistance (c) biomass (d) yield. 35. Nomenclature of enzymes is done on the basis of (a) the substrate on which they act (b) the type of reactions they catalyse (c) the end products formed (d) the co-factors they are associated with. 36. Some cells in adult animals do not divide. They exit G1 phase and enter an inactive stage which is called as (a) G2 phase (b) G0 phase (c) S phase (d) M phase. 37. Which of the below mentioned structures does not form a part of the endomembrane system? (a) Golgi complex (b) Endoplasmic reticulum (c) Mitochondria (d) Vacuoles 38. Which of the 4 names are correctly written as per rules of binomial nomenclature? (a) SOlANuM MElONGENA (b) Solanum melongena (c) Solanum Melongena (d) solanum melongena 39. Which of the following is correctly matched with its particular toxonomic category? (a) Triticum aestivum - Species (b) Fishes - Pisces - Phylum (c) Man - Primate - Family (d) Mango - Sapindales - Class 40. The group of fungi that are called fungi imperfecti are (a) Ascomycetes (b) Zygomycetes (c) Deuteromycetes (d) Basidiomycetes.

41. If the energy produced at the level of the producers is 1000 J, the energy available for the secondary consumers is (a) 1000 J (b) 100 J (c) 10 J (d) 1 J. 42. For the sedimentary type of biogeochemical cycles the reservoir is (a) atmosphere (b) water (c) earth’s crust (d) living organisms. 43. In hormone action, if receptor molecules are removed from the target organ, the target organ will (a) continue to respond to hormone (b) not respond to hormone (c) continue to respond but requires higher concentration (d) continue to respond, but in the opposite direction. 44. The principal nitrogenous excretory compound in humans is synthesized in (a) kidneys as well as eliminated by kidneys (b) liver, but eliminated mostly through kidneys (c) kidneys but mostly eliminated through liver (d) liver and also eliminated by the same through bile. 45. The flight muscles in an eagle has more of aerobic muscles. These muscles are also called “Red fibre” because they are rich in (a) haemoglobin (b) sarcoplasmic reticulum (c) myoglobin (d) globulin. 46. The correct path followed by sound waves from external ear to inner ear is (a) ear drum - basilar membrane - auditory ossicles - fluid of cochlea - hair cells (b) ear drum - auditory ossicles - fluid of cochlea - basilar membrane - hair cells (c) ear drum - fluid of cochlea - auditory ossicles - hair cells - basilar membrane (d) ear drum - hair cells - auditory ossicles - basilar membrane - fluid of cochlea. 47. The lobe of pituitary that secretes melanocyte stimulating hormone is (a) anterior lobe (b) posterior lobe (c) intermediate lobe (d) none of above. 48. Transport proteins of endodermal cells are control points, where a plant adjusts the quantity and type of solutes that reach the xylem. Root endodermis is able to actively transport ions in one direction only because of the layer of (a) actin (b) lignin (c) suberin (d) cellulose. MT BIOLOGY

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49. Water potential gradient between the absorbent and the liquid imbibed is essential for imbibition. In addition, for any substance to imbibe any liquid, one of the following is also a prerequisite. (a) Affinity between the adsorbant and the liquid (b) Molecular density of the adsorbant (c) Concentration of the adsorbant (d) Pressure potential of the adsorbant 50. The hormone that promotes rapid elongation of internode or petiole in deep water rice plant is (a) abscisic acid (b) ethylene (c) cytokinin (d) gibberellin. 51. Which of the below mentioned properties is not true with respect to facilitated transport? (a) Requires special membrane proteins (b) Transport saturates (c) uphill transport (d) Highly selective 52. Conversion of pyruvic acid into ethyl alcohol is facilitated by the enzymes (a) carboxylase (b) phosphatase (c) dehydrogenase (d) decarboxylase and dehydrogenase. 53. Which of the following is responsible for the production of progesterone, (the hormone responsible for the maintenance of endometrium)? (a) uterus (b) Graafian follicle (c) Corpus luteum (d) Ovary 54. The number of chromosomes in meiocyte (2n) in apple is (a) 24 (b) 380 (c) 34 (d) 20. 55. A contraceptive pill prevents ovulation by (a) blocking Fallopian tube (b) inhibiting release of FSH and lH (c) stimulating release of FSH and lH (d) causing immediate degeneration of released ovum. 56. A true fruit is one in which the fleshy part of the fruit is derived from the (a) thalamus (b) ovary (c) inflorescence axis (d) apocarpus gynoecium. 57. The sequence of amino acids in a protein is determined by (a) genetic code (b) m-RNA (c) t-RNA (d) r-RNA. 58. One of the methods by which DNA cannot be transferred to the host cell is by (a) microinjection (b) gene gun (c) disarmed pathogen vectors (d) polymerase chain reaction. 64

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59. Which of the following sequence is correct for the origin of lysosome? (a) Endoplasmic reticulum → Golgi complex → lysosomes (b) Nuclear membrane → Golgi complex → lysosomes (c) Endoplasmic complex → Vacuoles → lysosomes (d) Mitochondria → Golgi complex → lysosomes 60. A patient with bleeding gums is advised to take fresh fruits and vegetables in diet specially because he suffers from (a) scurvy (b) night blindness (c) beri-beri (d) anaemia.

Answer 1. 6. 11. 16. 21. 26. 31. 36. 41. 46. 51. 56.

(b) (c) (b) (b) (c) (a) (d) (b) (c) (b) (c) (b)

2. 7. 12. 17. 22. 27. 32. 37. 42. 47. 52. 57.

(b, c & d) (None) (b) (d) (b) (c) (d) (c) (c) (c) (d) (a)

3. 8. 13. 18. 23. 28. 33. 38. 43. 48. 53. 58.

(a) (a) (b) (a) (a) (d) (a) (b) (b) (c) (c) (d)

Key 4. 9. 14. 19. 24. 29. 34. 39. 44. 49. 54. 59.

(a) (a) (a) (b) (a) (b) (a) (a) (b) (a) (c) (a)

5. 10. 15. 20. 25. 30. 35. 40. 45. 50. 55. 60.

(c) (b) (a) (c) (a) (c) (a & b) (c) (c) (b) (b) (a)



Class XI

Animal Kingdom-III Phylum annelida

general CharaCters

–

1

1

4

1

–

– 7

4

3 –

J&K

BHU

–

6 –

K.CET

6

–

2 –

5

2 –

4

8 2 Kerala

4

3

4 5

2 –

2 3 –

1

8 3

2012 2011

4 4

2010

–

•

AMU

•

AIIMS

• • •

2

• •

2009

•

AIPMT/NEET

• •

Analysis of various PMTs from 2009-2014

•

2013

• Mostly •

aquatic, some terrestrial, burrowing or tubicolous. Some commensal and parasitic. Body elongated, bilaterally symmetrical, triploblastic, truely coelomate and metamerically segmented into similar metameres. Epidermis of a single layer of columnar epithelial cells, covered externally by a thin cuticle not made of chitin. Body wall dermo-muscular. Outer muscle fibres circular, inner longitudinal. Locomotory organs are segmentally repeated chitinous bristles, called setae or chaetae, embedded in skin. May be borne by lateral fleshy appendages or parapodia. Coelom, true, schizocoelous. Mostly well-developed except in leeches. Usually divided into compartments by transverse septa. Coelomic fluid with cells or corpuscles. Digestive system straight and complete. Digestion entirely extracellular. Blood vascular system closed. Respiratory pigments either haemoglobin or erythrocruorin dissolved in blood plasma. Respiration by moist skin or gills of parapodia and head. Excretory system consisting of metamerically disposed coiled tubes, called nephridia. Nervous system with a pair of cerebral ganglia (brain) and a double ventral nerve cord bearing ganglia and lateral nerves in each segment. Sensory organs include tactile organs, taste buds, statocysts, photoreceptor cells and sometimes eyes with lenses in some. Both unisexual (e.g., Neries) and bisexual (e.g., Earthworm, Leech) forms are found. Cleavage spiral and determinate. Larva, when present, is a trochophore. Regeneration common.

1

2014

which developed metameric segmentation.

4

• The term Annelida was first coined by Lamarck for the higher segmented worms. • The annelid worms were thought to be evolved from coelomate worm like ancestors

nephridia • Nephridia are segmentally arranged coiled tubes of ectodermal origin developed as invaginations from ectoderm into

coelom. • They communicate with the exterior through laterally placed small apertures called nephridiopores. • Nephridia are of two types, protonephridia and metanephridia. • Protonephridia are closed nephridia as they terminate in the coelom as blind tubes. The closed end of protonephridium is

provided with peculiar specialised excretory tube cells or solenocytes. These are similar to flame cells of platyhelminthes. • Protonephridia is found in all larval polychaetes and some adult polychaetes such as Vanadis, Phyllodoce, etc. • Metanephridia are open nephridia, as instead of solenocyte, the inner end of metanephridium opens into coelom by a ciliated

funnel or nephrostome. • Metanephridia are more advanced and found in the majority of polychaetes, all oligochaetes and leeches. • Nephridia may be micronephridia or meganephridia on the basis of their size and number. Micronephridia or

meronephridia are smaller in size and found in oligochaetes. Meganephridia or holonephridia are larger in size and found in polychaetes and leeches. • Nephridia are termed exonephric or ectonephric when they directly open to the exterior through nephridiopores, such as

meganephridia of Nereis and Hirudinaria and integumentary micronephridia of Pheretima. • Nephridia are termed enteronephric when they lack nephridiopores and open into the excretory canals or alimentary canal,

such as, septal or pharyngeal nephridia of Pheretima. • Nephridia are primarily excretory in function but may secondarily serve to convey the genital products to the exterior.

metamerism • When the segmentation in bilateral animals, such as annelids, involves a longitudinal division of the body into a linear series of

similar sections or parts, it is termed as metameric segmentation or metamerism. Each section or part is called a segment, somite or metamere. Each metamere typically repeats some or all of the various organ units. The term metamerism is applied only when organs of mesodermal origin are so arranged. • Metameric segmentation of the body, encountered for the first time in Annelida, is of considerable interest because the most

successful groups of animal kingdom, i.e., Arthropoda and Vertebrata, also have their parts metamerically repeated. • True metamerism, as shown by annelids, must not be confused with the pseudometamerism or strobilisation of the

tapeworms, which refers to superficial segmentation and could be termed body annulation.

unique features

advanCement over round worms

• They are first animals to have metamerically segmented

• Presence of metameric segmentation. • Presence of true coelom. • Presence of circular and longitudinal muscles in both the

body. • They are first animals to have true coelom. • They are first animals to have a closed vascular system. • Presence of haemoglobin or erythrocruorin

in plasma. have nephridia for excretion and osmoregulation. • Presence of setae and parapodia for locomotion. • Morphologically and anatomically very similar to arthropods but embryologically most similar to molluscs. • They

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body wall and the wall of alimentary canal. • Presence of locomotory organs such as setae and parapodia. fluid as • Schizocoelomic hydroskeleton. • Presence of cutaneous and branchial respiration. • Presence of circulatory system. • Nervous system consists of nerve ring, nerve cord and ganglia.

• Presence of tactile receptors (receptors of touch),

gustatoreceptors (receptors of taste), photoreceptors (sensitive to light) and statocysts (balancing organ).

ClassifiCation of annelida • Annelida are divided into four main classes, primarily on

the basis of the presence or absence of parapodia, setae, metameres and other morphological features: Polychaeta, Oligochaeta, Hirudinea and Archiannelida.

• Fertilisation external (in cocoon), development direct without

any larval stage. • Examples : Pheretima, Tubifex, etc. Chaetopoda is a super group which includes both Polychaeta and Oligochaeta. This creation is because of the fact that both the classes are provided with setae.

Class hirudinea • It comprises leeches which are perhaps the most specialised

annelids without parapodia and setae but with suckers. • About 300 species of leeches are known to occur in the

tropical and temperate parts of the globe. • Most of the leeches are freshwater, while some are marine

or terrestrial. • Most are ectoparasitic, living on the blood of vertebrates,

while some are predaceous, feeding on worms, snails, insects, larvae etc. • Body with fixed number of segments (33). Each segment is

subdivided externally into annuli. • Coelom much reduced due to its filling by botryoidal tissue

and forms haemocoelomic sinuses. • Hermaphroditic, with one male and one female gonopore,

Class Polychaeta • It is the largest class which includes marine worms. Some

are fresh water. • As their name implies, each body segment bears numerous

setae on a pair of lateral appendages, the parapodia.

but cross fertilisation occurs. Fertilisation internal. Segments 9, 10 and 11 develop a temporary clitellum during breeding season. • Development in cocoons, direct without larval stages. • Examples : Hirudo, Hirudinaria etc.

• Head distinct with eyes, palps and tentacles. • Clitellum absent. • Sexes separate. Gonads temporary and in many segments. • Development includes trochophore larva. • Examples: Aphrodite, Nereis, Chaetopterus, Arenicola, etc.

Class oligochaeta • It includes terrestrial earthworms and some other species

that live in fresh water. • The members of this class possess few locomotory setae

borne directly by body segments which are devoid of parapodia. • Burrowing, crawling, nocturnal and detritivorous in habit. • Head indistinct and without sensory organs. • Glandular clitellum present for cocoon formation. • Hermaphroditic. Testes anterior to ovaries. MT BIOLOGY

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Class archiannelida • It includes about one dozen genera of small, marine worms

of unknown affinities.

•

• Segmentation chiefly internal. • Parapodia and setae are absent. • Sexes usually separate. • A trochophore larva is usually present during development

stage. • Examples : Polygordius, Dinophilus, etc.

• • •

• Some authors have classified Annelida into 5 classes. Fifth

class is Echiurida. The members of this class are without external and internal segmentation. Setae are rare. E.g., – Bonellia, Echiurus.

• •

eConomiC imPortanCe of annelida • In terms of influence on human welfare or economic

importance, the earthworms (Oligochaeta) and leeches (Hirudinea) are more important than the polychaetes.

economic importance of Polychaeta • The sexual parts or epitokes of palolo worms are used as

food by the native people. Epitokes are highly nutritive consisting of almost pure yolk-laden eggs. • Lugworm (Arenicola) is a circulator of soil and considered

even more effective than the common earthworm. It is also one of the commonest baits for certain fish. • Some sand and lime-concreting tubicolous polychaetes are

important reef-building agents in some parts of the world. • Species of Polydora (harmful polychaetes) are oyster -

pests, causing mud blisters in the nacreous layers of shells and making the oysters unfit to be sold. Oyster growers call it “worm disease”.

economic importance of oligochaeta • All over the world earthworms are used as bait for

fishing. • A small white earthworm (Enchytraeus albidus) is often

•

grown in soil and used to feed aquarium fish and small laboratory animals. Earthworms are used as food by uncivilised people in many parts of the world. They are eagerly hunted as food by birds, frogs, moles, lizards, small snakes and other predatory invertebrates. Earthworms are in general beneficial to agriculture. Their habit of burrowing and swallowing earth increases fertility of soil in many ways. Their burrows permit penetration of air and moisture in porous soil, improve drainage, and make easier the downward growth of roots. Earthworms were used variously as medicines in the past. Earthworms were used to cure stones in bladder, yellowness of jaundice, pyorrhoea, piles, rheumatism or gout and diarrhoea. They are easily obtained and are of convenient size to be used for dissections. They are, therefore, universally employed for class studies and for investigation in general and comparative physiology.

• Earthworms are said to serve as intermediate hosts in

the transmission of some parasites, such as tapeworm (Amoebotaenia sphenoides) and gapeworm (Syngamus) of chicken and lung nematode (Metastrongylus elongatus) of pigs.

economic importance of hirudinea • Most of the leeches are economically very significant for

medicinal purposes. • Phlebotomy or ‘blood-letting’, painlessly achieved

by the application of leeches, was a common, though erroneous method of medical treatment in Europe in the early nineteenth century. • When a person got a ‘black eye’ or conspicuous black and

blue spots on the body, the doctor used to apply a lean hungry leech to the skin for sucking the impure blood. • Salivary glands of leeches secrete anticoagulating substance,

called hirudin or anticoagulin.

1.

Describe ectonephric nephridia.

2.

How is strobilisation different from true metamerism?

3.

How are earthworms beneficial to agriculturists?

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Table : Important examples of Phylum Annelida Scientific name

Common name

Important features

Class-Polychaeta Nereis

Sand worm or ragworm or clamworm

• Nereis is a cosmopolitan marine polychaete, living in U-shaped burrows in

sand or mud. • It is carnivorous and nocturnal in habit. • Body is divisible into head, trunk and pygidium. • Peristomium is the first segment of the body which is devoid of parapodia

but bears two pairs of thread like peristomial cirri on each side. • Pygidium is the last segment of body and is also devoid of parapodia and

setae. • Parapodia are flattened, fleshy, vertical flap-like outgrowths of body wall on

the lateral sides of trunk segments. Each parapodium bears a bundle of long, fine, stiff, chitinous bristles, the setae or chaetae. Parapodia serve the dual purpose of locomotion and respiration. • Body wall consists of cuticle, epidermis, musculature and coelomic

epithelium or peritoneum. • Peritoneal cells lining the coelom secrete the coelomic fluid and give rise to

gonads during breeding season. • Gills or any other special organs of respiration are lacking. Respiration is

carried out by whole body surface, more specially by thin flattened lobes of parapodia. • Nitrogenous waste is mostly ammonia. • Sense organs include prostomial tentacles, prostomial palps, nuchal organs,

peristomial cirri and 2 pairs of eyes. • Most of the species of Nereis are unisexual (dioecious). Gonads (testes and

ovaries) are neither distinct nor permanent organs and formed only during breeding season. • In Nereis there are no gonoducts. • At sexual maturity, most of the posterior segments, filled with gametes, exhibit

morphological and anatomical differentiation. These constitute the sexual region or epitoke of worm. Few anterior segments which do not take part in gamete formation, constitute the asexual region or atoke. • Sexually mature worm with these two regions is known as Heteronereis and

the phenomenon involving transformation of non-sexual individual into sexual individual is referred to as epitoky. • Fertilisation is mostly external and takes place in sea water. • Development is indirect including larval stage, i.e., trochophore.

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Class-Oligochaeta Pheretima posthuma

Earthworm

• It is commonly found in South-East Asia, japan, Sri Lanka and Australia and is

represented by 13 species in the Indian soil.

• It is a terrestrial earthworm living in burrows made in moist earth. • It feeds on dead organic matter present in soil. Food and soil are ingested

• • • •

•

together and the latter along with undigested food is finally egested in the form of worm castings. Brown colour of worm is due to the pigment porphyrin present in body wall and it protects the body against strong bright light. Body is divisible into 100 to 120 similar segments called metameres or somites. These are without parapodia. It lacks a distinct head and sense organs like eyes, cirri and tentacles. In mature worms, a girdle like thick band of glandular tissue, the clitellum completely and permanently surrounds the segments 14 to 16. It is a glandular organ which secretes mucus, albumen and an egg case or cocoon for eggs. About 80 to 120 setae are present on each segment. They are absent on peristomium, pygidium and the clitellum.

• There are two pairs of genital papillae, one pair each in 17th and 19th

segments.

• First or anterior part lying between segments 15 to 26 is known as pre-

•

•

• • •

• •

•

•

•

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typhlosolar region. Its wall is internally folded to form minute processes, the villi, and is highly vascular. Second or middle part lies between 27th segment upto 23-25 segments in front of anus. It is characterised by the presence of a highly glandular and vascular longitudinal ridge, arising as a median ingrowth of the dorsal aspect of the intestine cavity. This is called typhlosole. Third or the last part also known as rectum, is of about 23-25 segments. It is internally marked by the presence of longitudinal folds. It opens to outside through a terminal anus. In each of the segments 7, 9, 12 and 13 is found a pair of large, thick, muscular and rhythmically contractile vertical vessels called hearts. Earthworms are both ammonotelic and ureotelic. The main excretory organ is nephridia. Three types of nephridia are found in the earthworm according to their location, namely the septal nephridia, pharyngeal nephridia and integumentary nephridia. Pharyngeal nephridia are paired and occur in segments 4, 5 and 6. They are enteronephric. Integumentary nephridia occur in all segments except the first two segments. There are 200 - 250 nephridia in each segment but in the segments of clitellum (segments 14 to 16), their number increases to more than 2000 constituting the ‘forests of nephridia’. They are exonephric. Septal nephridia are largest nephridia of Pheretima and are attached to both the faces of each intersegmental septum behind 15th segment. They are enteronephric. Chloragogen cells or yellow cells are supposed to remove some excretory wastes from blood and coelomic fluid. They are analogous to the liver of vertebrates. They also store glycogen and fat. Earthworms do not reproduce asexually. These are monoecious but cross fertilisation is rule, because of protandry i.e., testes mature earlier than

• There are four pairs of small flask-shaped structures, called spermathecae

or receptacula seminales, one pair in each of the segments 6, 7, 8 and 9. These receive sperms from another worm during copulation, and store them in their diverticula. • Fertilisation is external and takes place in cocoon or egg capsule. A cocoon may contain many fertilised eggs but only one embryo develops, growing at the expense of other eggs serving as nurse cells. • Development direct. Newly hatched young worm receives no parental care and resembles the adult except for size and absence of clitellum. Class – Hirudinea Hirudinaria granulosa

The Indian cattle leech

• It occurs in freshwater ponds, lakes, tanks, swamps and slow streams. • It has a blood sucking (sanguivorous) habit, feeding on the blood of fish and

frogs and also of cattle and man.

• Skin is moist and shiny due to abundant secretion of mucus, which helps in • • • • • •

• • • • • • • • •

cutaneous respiration. Body is metamerically divided into 33 segments or somites. Except the first two and the last seven, each segment is further superficially subdivided into rings or annuli. A typical segment possesses five annuli. A temporary clitellum is formed by segments 9th, 10th and 11th, during breeding season. The 5 pairs of eyes appear as a semicircle of black dots at the anterior end. A pair of suckers (anterior or cephalic sucker and posterior or anal sucker) are primarily meant for adhesion and locomotion. Beneath the longitudinal muscles and immediately surrounding the alimentary canal is found the characteristic botryoidal tissue. This tissue fills the entire coelom except a few spaces termed the haemocoelomic spaces. Mouth leads into a muscular suctorial pharynx. Cavity of pharynx alternately expands and contracts to serve as a suction pump so that blood oozing from the host’s wound is sucked in. Secretion of salivary gland contains hirudin or anticoagulin which prevents coagulation of blood while the leech is feeding. Blood vascular system is replaced by haemocoelomic system. Excretory system consists of 17 pairs of nephridia, one pair in each segment from 6th to 22nd. Nephridia are of two types, testicular and pre-testicular. Nitrogenous waste is mostly ammonia and small quantities of urea. Leeches do not reproduce asexually. They are hermaphroditic, however, cross fertilisation by copulation is a rule. Internal fertilisation takes place in the vagina of each individual and the fertilised ova are discharged into a cocoon for further development. Development direct without any larval stage. Class - Archiannelida

Polygordius

• It is a marine worm with a narrow, elongated and cylindrical body which is 3

to 10 cm long. • External segmentation is indistinct. • Parapodia, setae, cirri and gills are altogether absent. • Coelom is completely divided by septa. Each segment of coelom contains a

pair of metanephridia. • It is unisexual. • Development includes a larval stage. Larva is called as Loven’s larva (typical

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Phylum arthroPoda

PhysiologiCal CharaCters

• Phylum Arthropoda (Gk. arthros = joint + Podos = foot) is the

digestive system

largest phylum of Kingdom Animalia. • They are important members of marine, freshwater and land ecosystems and are one of the two major groups that have adapted to life in dry environments. The other group is amniotes (reptiles, birds and mammals).

general CharaCters • The body is segmented externally and the segments are

grouped into two regions called tagmata (singular, tagma). There may be two tagmata, head or cephalothorax and trunk or abdomen or three tagmata, head, thorax and abdomen. The segments are not separated internally by septa. The body is of varying shapes having bilateral symmetry. Arthropods are triploblastic with three germ layers i.e. ectoderm, endoderm and mesoderm. Arthropods have organ-system level of organisation with a tube-within-a-tube body plan. Tube-within-a-tube body plan corresponds to presence of a complete digestive tract i.e., with mouth and anus inside the body cavity. The body walls consists of a thick, chitinous cuticle and a single layered epidermis.

• • •

•

• It is complete and consists of a digestive tract divided into

3 distinct regions : stomodaeum (foregut), mesenteron (midgut) and proctodaeum (hindgut). • Digestion is intercellular or extracellular. • Mouth consists of movable appendages, the mouth parts are adapted for chewing, sucking, sponging etc. To understand the mouth parts found in arthropods, insects are taken as model.

Circulatory system • Circulatory system is of open type, or lacunar type i.e.,

blood does not flow in definite vessels. • Blood flows in haemocoel. Haemocoel is made up of irregular spaces known as lacunae or sinuses. • Blood is colourless and contains WBCs only. It is also known as haemolymph. • Dorsal, often many-chambered, pulsatile heart is present.

respiratory system • Respiration takes place either by general body surface

or by special structures such as gills, book gills, book lungs and tracheal system. Different types of respiratory organs are found in different groups of Arthropoda.

Cuticle • Cuticle, a characteristic feature of arthropods, is thick,

non-living and horny or chitinous layer. It forms the exoskeleton. It is secreted by hypodermis or epidermis. The hard cuticle restricts growth and is periodically shed during growth by a process known as ecdysis. Cuticle is one of those features of arthropods which are primarily responsible for their success on land. Some specific features of cuticle are : – It provides support, an essential requirement of terrestrial animals. – It provides rigidity. In insects, the flight depends on the possession of rigid wings, which is provided by cuticle. – It provides protection. Arthropods have hardened, heavily sclerotized cuticle which makes them difficult for predators to catch or parasites to parasitise. – Wax layer of cuticle restricts the water loss. – Cuticle is also modified to form sense organs like sensilla on antennae of various insects in the form of hair (Bombyx), pegs (locusts), flat plates (bees and aphids). • The body cavity around the viscera contains blood and is called

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excretory system • Excretory organs are green glands and Malpighian

tubules. • Green glands are also called as antennal or antennary

•

•

•

•

glands. They are found in pair in the third segment of crustaceans. They open to the exterior at the base of second antenna and serve as osmoregulatory and excretory organ. Malpighian tubules are small tubular structures that are involved in excretion of nitrogenous wastes and are found in insects, arachnids and centipedes. In insects, they open into the intestine. They selectively extract uric acid from blood which along with water and salts is deposited into the hindgut and excreted in faeces. Some reabsorption may occur in tubules but most of it occurs in hindgut. In some forms coxal glands are excretory organs. They are paired ducts that lead from coelom to exteriors and are common in arachnids where they are found in cephalothorax opening at bases (coxae) of legs, thus named so. Coxal glands and green glands open to exterior while Malpighian tubules open inside the body cavity in some organ, mostly intestine.

• Excretory product is ammonia/urea in aquatic forms and uric

acid in terrestrial species.

• jointed appendages modified for a variety of functions.

nervous system

• Tough jointed exoskeleton of chitinous plates.

• Nervous system is ladder-like i.e., annelidan type. It has

paired preoral ganglia (cerebral and suboesophageal), connectives (longitudinal nerve bands), commissures (lateral nerve bands) and a double ventral nerve cord having ganglia and nerves. A pair of ganglia are found at each segment. • Antennae are absent in arachnids e.g., spiders etc. Antennae are two pairs in crustaceans e.g., freshwater prawn etc., and single pair in others e.g., centipede (Scolopendra), millipede (Julus), cockroach etc. • The sense organs comprise chemo and tactile receptors. In many arthropods, compound eyes forming mosaic vision are well developed. A balancing organ called statocyst is also present in some.

reproductive system • Sexes are usually separate (dioecious) and sexual

•

•

•

•

dimorphism is observed in many forms. Reproductive organs and ducts are paired. Fertilisation is usually internal. The animals are oviparous and occasionally ovoviviparous e.g., scorpion. Eggs are macrolecithal, cleidoic and mostly centrolecithal. Development may be direct or indirect with many larval stages which undergo metamorphosis to produce the adult form. Some forms show parthenogenesis i.e., development of an egg into a complete individual without fertilisation e.g., male honey bees (drones). The level of maternal care for hatchlings varies from nonexistent to the prolonged care provided by scorpions.

larvae of arthropods larvae of crustaceans • Nauplius • • • • • •

Metanauplius Protozoaea Zoaea Megalopa Phyllosoma Alima

larvae of insects • Maggots or gentles • Wriggler • Grubs • Caterpillar

unique features

• Trachea, book lungs, book gills, etc. for respiration. • Antennary glands or green glands, Malpighian tubules and

coxal glands for excretion and osmoregulation. • Presence of compound eyes in most forms. • Body

cavity is haemolymph.

haemocoel

and

blood

is

called

• Secretion of pheromones (a volatile chemical substance)

in some forms. • Power of flight in most insects.

advanCement over annelida • Well developed head, distinct from other regions of body. • Well developed chitinous exoskeleton. • Jointed appendages adapted for different functions. • Striped muscles arranged in bundles for moving particular

parts.

advantage of discontinuous muscle bundles Annelids have somatic musculature in the form of continuous muscular layers. In arthropods, on the other hand, due to much jointedness of body and limbs, the musculature consists of separate striated muscles, attached to the inner surface of the exoskeleton. The jointed exoskeleton on body and appendages, with its associated discontinuous muscles provides for a great variety of specialised movements. Each joint has flexor muscles which bend it, and extensor muscles which straighten it out. • Well developed sense organs e.g., compound eye, statocyst,

taste receptor, sensory hair etc. Characteristic larvae of the class crustacea Apus Euphausia Crabs Brachyuran decapods Palinurus Squilla Musca domestica Mosquitoes Honey bee, beetles Silkworm

• Development of endocrine glands for secretion of

hormones. • Secretion of pheromones for communication. • Special respiratory organs such as trachea, book gills

and book lungs which were absent in annelids. • Development of eyes (simple and compound eyes) which

were not so well marked in annelids.

ClassifiCation of arthroPoda • Arthropoda is a much heterogenous group. The versatility

of the arthropod modular body plan has made it difficult for zoologists to classify them. Because of this, no definitive

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system of classification of arthropods exists. The classification adopted here is a synthesis of several views. • According

to the majority of zoologists, Phylum Arthropoda is classified into seven subphyla and six classes. • Of these, only trilobitomorpha, chelicerata and mandibulata are definitely

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arthropods while onychophora, tardigrada, pentastomida and pycnogonida show only doubtful or superficial relationships with other arthropods. • Earlier diplopoda and chilopoda were treated as orders and were included in a single class myriapoda with two more orders. These were – pauropoda (e.g., Pauropus) and symphyla (e.g., Scutigerella). • Now, all of these are considered as separate classes.

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reasons for biological success of arthropoda • Some structural and biological patterns which have

contributed to the big biological success of arthropods are : – Thick chitinous exoskeleton – jointed body and limbs – Locomotion by small, striated, extrinsic muscles – Various specialisations of somites, alimentary canal and respiratory organs – Cephalisation with concentration of ganglia and sense organs in head region – Behaviour patterns with primitive intelligence and social instincts in some group. Scientific study of crustaceans is known as carcinology and acarology is the scientific study of ticks and mites. Entomology is the scientific study of insects. • Characteristics of some important classes of Phylum

Arthropoda are summarised in a table on next page.

Class inseCta • Class Insecta of Phylum Arthropoda is the largest in the

•

• • •

animal kingdom, as there are more species of insects (about 7,50,000) than all other species of animals combined. Insects are air breathing and usually flying arthropods. They are distinguished from other arthropods by the possession of 3 pairs of legs and usually 2 pairs of wings which may be absent in some. Body made up of head (6 fused segments), thorax (3 segments) and abdomen (upto 11 segments). Head with compound eyes (1 pair), antennae (1 pair), mandibles (1 pair) and maxillae (2 pairs). Class Insecta, Diplopoda and Chilopoda can be grouped in a taxon called tracheata due to presence of tracheal system as respiratory organ.

types of mouth parts in insects • Mouth parts in insects are modified for different feeding

habits. • In general, mouth parts of an insect

consist of one labrum, one labium, one hypopharynx, two mandibles and two maxillae. As insects feed on animals and plants in a diversity of ways, their mouth parts are modified for these purposes. Important types of insect mouth parts are described as follows : 76

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metamorphosis in insects • In case of insects where development is usually indirect the

egg hatches into a dissimilar larva instead of a miniature adult. • Transformation of an immature larval individual into a sexually mature reproducing adult of very different form, structure and habit, is called metamorphosis. • Insects display four types of metamorphosis: –

No-metamorphosis or ametabolous development : In ametabolous development, metamorphosis does not occur. These insects are most primitive and wingless. E.g., silver fish, spring tails. – Incomplete metamorphosis or hemimetabolous development : In this type of metamorphosis, the life history includes egg, naiad (young) and imago (adult). Young is aquatic and respires by tracheal gills, whereas, the adult is aerial and respires by tracheae. E.g., mayflies, dragon flies, and stone flies.

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Sexes separate. Development direct. Scolopendra, Scutigera, Lithobius etc.

Chewing type

Body surface or gills

Green glands

Two pairs

Compound eyes

Sexes separate, Development is usually indirect. Characteristic larva is nauplius.

Prawn, Crab, Crayfish, Daphnia, Cyclops, Shrimp, Lobsters etc.

Mouth parts

Respiratory organ

Excretory organ

Antennae

Eyes

Reproduction

Examples

Absent or one to many ocelli, compound eyes are present in centipedes.

One pair

Malpighian tubules

Tracheae

Chewing type

Spirobolus, Julus etc.

Sexes separate. Development direct.

Simple eyes

One pair

Malpighian tubules

Tracheae

Chewing type

Cockroach, Apis Bombyx, Mosquitoes, Housefly, Butterfly etc.

Sexes separate. Development may be direct or indirect.

Compound eyes

One pair

Malpighian tubules

Tracheae

Various types e.g., siphoning, sucking etc.

Each abdominal segment There are three pairs bears two pairs of of legs in the thorax jointed legs. and two pairs of thoracic wings which may be absent in some. Abdomen is with appendages.

Each trunk segment bears a pair of jointed legs, terminating into claws. First pair of legs bear poison apparatus.

Each body segment bears a pair of biramous appendages which are variously modified for feeding, swimming, respiration and reproduction. Appendages are present on abdomen as well as thorax.

Appendages

Head, thorax and abdomen

Mostly terrestrial, rarely aquatic

Insecta (Largest class in animal kingdom)

Body elongated, sub-cylindrical and divisible into head, thorax and abdomen.

Terrestrial

Diplopoda (Millipedes)

Body elongated, dorsoventrally compressed and divisible into head and trunk.

Body consists of cephalothorax (covered by carapace in some) and abdomen.

Body segments

Terrestrial

Chilopoda (Centipedes)

Mostly marine but a few live in freshwater or moist places, some are parasites.

Crustacea

Habitat

Character

Class

Table : Some important classes of Phylum Arthropoda and their main characteristics

Sucking type

Cephalothorax bears a pair of chelicera and five pairs of chelate legs. Five-six pairs of abdominal appendages are also present. Abdomen ends in a sharp telson or spine.

Cephalothorax and abdomen

Mostly marine

Merostomata

Scorpion, Spider, Tick, Mite etc.

Sexes separate. Development is generally direct.

Simple eyes

Absent

Malpighian tubules and coxal glands

Limulus, Eurypterus, Pterygotus.

Sexes separate. Development indirect.

Median, simple and lateral compound eyes

Absent

Coxal glands

Book lungs, tracheae Book gills or both

Sucking type

Four pairs of legs are present over cephalothorax. Abdomen is without appendages.

Cephalothorax and abdomen

Mostly terrestrial

Arachnida

Egg Mature adult

Aquatic naiad

Aerial imago

– Gradual metamorphosis or paurometabolous

development : In this type of metamorphosis, the life history includes egg, nymph (young) and imago (adult). The nymph resembles an adult in general body form, but lacks wings and external genital appendages. E.g., cockroaches, grasshoppers, locusts, termites, stick insect, praying mantis, bed bug and lice etc.

– Complete metamorphosis or holometabolous

development : In this type of metamorphosis, the life history includes four developmental stages – egg, larva, pupa and imago (adult). Larva after hatching, moults several times to become a fully grown adult. It later becomes a pupa within a secreted case, called puparium. Pupa differentiates into the young adult that breaks the puparium open and emerges out. It grows to a mature form, e.g., butterflies, moths, beetles, houseflies, mosquitoes, fleas, honey bees, ants, wasps, etc.

– Juvenile hormone (JH) : This hormone is secreted by

corpora allata. This hormone regulates morphogenesis and so promotes metamorphosis, that is development of the larvae into adult through pupal stage. • The Class Insecta is divided into 30 orders. The most important orders with common examples are listed in the table given as follows : Table : Important Orders of Class Insecta with examples Orders Examples Thysanura Lepisma (Silver fish) Schistocerca (Locust), Poecilocerus Orthoptera (grasshopper), Gryllus (House cricket) Periplaneta (Cockroach), Mantis (Praying

Isoptera Odonata Anoplura Ephemeroptera Hemiptera Homoptera Coleoptera Lepidoptera Diptera

• Metamorphosis or post embryonic growth of insects, is

under hormonal control. The various hormones secreted are as follows : – Brain hormone (BH) : It is secreted by the neurosecretory cells of the brain. It serves to activate corpora cardiaca. – Prothoracicotropic hormone (PTTH) : This hormone is secreted by the corpora cardiaca, which in turn stimulates the prothoracic glands. – Prothoracic gland hormone (PGH) : This hormone is secreted by the paired, bilateral sheet of cells in thorax, constituting the prothoracic glands. This hormone is known to trigger moulting as it acts on the tissues to promote all of the changes characterising a moult. 78

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Siphonaptera Hymenoptera

mantis). Microtermes (Termites or white ants). Sympetrum (Dragon fly). Pediculus (Human louse). Ephemera (Mayfly). Cimex (Bed bug), Dysdercus (Red cotton bug). Aphis (Aphid = Plant louse), Laccifer lacca or Tachardia lacca (lac insect). Coccinella (Lady bird beetle), Sitophilus (Grain Weevil). Bombyx (Silk moth), Pieris (Cabbage butterfly). Musca (Housefly), Anopheles, Culex, Aedes (All the three mosquitoes). Xenopsylla cheopis (Rat flea). Apis (Honey bee), Vespa (Wasp).

onycophora : the Connecting link • Subphylum Onycophora that consists of unsegmented

terrestrial, primitive worm-like arthropods which resemble both annelids and arthropods is considered as connecting link e.g., Peripatus. • They resemble annelids in worm like body, indistinct head, thin flexible cuticle, unjointed appendages, segmentally arranged nephridia and ciliated genital ducts. • They resemble arthropods in having clawed legs, antennae, haemocoel, salivary glands, tracheae and dorsal tubular heart with lateral ostia.

4.

The group of triploblastic animals with jointed appendages, bilateral symmetry, having open circulatory system and possess antennary glands or green glands and Malpighian tubules as excretory organs. (a) Name the phylum to which they belong. (b) Name the subphylum which contains their fossil representatives. (c) Give three examples of the class having three pairs of legs and usually two pairs of wings.

1. Peristomium in Nereis is composed of (a) one segment (b) two segments (c) three segments (d) six segments. 2. The name of the larva of Nereis is (a) trochophore (b) bipinnaria (c) zoea (d) cercaria. 3. In earthworm, the spermathecae are used for (a) development of ovum (b) development of sperm (c) storing spermatozoa (d) development of zygote. 4. Saliva of leeches contain an anticoagulant called (a) haemoglobin (b) hirudin (c) haparin (d) histamine. 5. Presence of coelom and metamerism are the most important characters of

(a) helminthes (c) annelids

(b) poriferans (d) coelenterates.

6. Typhlosole is present in the intestine of (a) Nereis (b) Hirudinaria (c) Pheretima (d) Aphrodite. 7. The clitellum in a mature Pheretima is a thick girdle which is (a) glandular in nature and surrounds segments 16-18 (b) non-glandular in nature and surrounds segments 16-18 (c) glandular in nature and surrounds segments 14-16 (d) non-glandular in nature and surrounds segments 14-16. 8. Heteronereis stage is (a) transformation of sexual individual into asexual (b) sexually immatured worm with two regions atoke and epitoke (c) sexually matured worm with two regions atoke and epitoke (d) all of the above. 9. In which of the following classes of Annelida, clitellum is absent?

(a) Hirudinea (c) Oligochaeta

(b) Polychaeta (d) All of these

10. Which of the following assists in the locomotion of the organism stated ?

(a) (b) (c) (d)

Clitellum of Pheretima Pedicellaria of starfish Trichocysts of Paramecium Posterior sucker of Hirudinaria

11. The nephridia in earthworm are analogous to (a) nematoblasts of Hydra (b) flame cells of Planaria (c) gills of prawn (d) trachea of insects. 12. Chitin is a polysaccharide found in the exoskeleton of (a) prawn (b) insects (c) crabs (d) all of these. 13. Antennary glands of crustaceans are meant for (a) respiration (b) neurosecretion (c) excretion (d) olfaction. 14. Which one of the following features is possessed by crustaceans and not by insects?

(a) Paired limbs (b) Two pairs of antenna (c) Chitinous exoskeleton (d) Bilateral symmetry 15. Bilateral symmetry, metameric segmentation, coelom and open circulatory system characterise which of the following phyla?

(a) Annelida (b) Mollusca (c) Arthropoda (d) Echinodermata 16. Which of the following is not an insect? (a) Termite (b) Ant (c) Mosquito (d) Spider 17. Most of the insects excrete uric acid because (a) most of them are aquatic (b) most of them are terrestrial (c) the circulatory system is open (d) the blood is colourless. 18. Match Column I with Column II and select the correct option. Column I Column II A. Polychaeta (i) Pheretima B. Oligochaeta (ii) Polygordius C. Hirudinea (iii) Nereis D. Arachiannelida (iv) Hirudinaria MT BIOLOGY

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(a) A-(iii), B-(i), C-(iv), D-(ii) (b) A-(i), B-(iii), C-(iv), D-(ii) (c) A-(iv), B-(ii), C-(i), D-(iii) (d) A-(ii), B-(iii), C-(iv), D-(i) 19. Which of the following statements is not true regarding arthropods?

(a) (b) (c) (d)

Organ system level of body organisation Exoskeleton of dead chitinous cuticle Digestive system complete with mouth and anus Circulatory system closed

20. Select the mismatched pair out of the following. (a) Biting and chewing type – Grasshoppers and cockroaches (b) Piercing and sucking type – Female mosquitoes (c) Chewing and lapping type – Honey bees and bumble bees (d) Sponging type – Mosquitoes and crickets 21. Select the correct statement(s) regarding incomplete metamorphosis.

(a) The life history includes egg, naiad and imago. (b) Young respires by tracheal gills whereas adult respires by trachea. (c) Examples include mayflies, dragon flies etc. (d) All of these. 22. Which of the following is wrongly matched? (a) Haemoglobin in mammals - RBC (b) Haemozoin - Plasmodium cytoplasm (c) Haemocyanin - prawn (d) Haemoglobin dissolved in blood - Pheretima 23. Which one feature is common to leech, cockroach and scorpion?

(a) Nephridia (c) Cephalisation

(b) Ventral nerve cord (d) Antennae.

24. Which one of the following features is common in silver fish, scorpion, dragon fly and prawn?

(a) (b) (c) (d)

Three pairs of legs and segmented body Chitinous cuticle and two pairs of antennae jointed appendages and chitinous exoskeleton Cephalothorax and tracheae

25. Peripatus is known as connecting link, because it has the characters of both

(a) fishes & amphibians (b) reptiles & birds (c) aves & fishes (d) arthropoda & annelids. 26. Which one of the following is not a characteristic of Phylum Annelida?

(a) Pseudocoelom (b) Ventral nerve cord (c) Closed circulatory system (d) Segmentation 27. Which is not a feature of annelids ? (a) Metameric segmentation (b) Nephridia (c) Pseudocoelom (d) Clitellum 80

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28. Malpighian tubules are (a) excretory organs of insects (b) respiratory organs of insects (c) excretory organs of frog (d) endocrine glands of insects. 29. Which of the following is not a characteristic feature of arthropods?

(a) jointed appendages (b) Unsegmented body (c) Moulting (d) Articulated exoskeleton 30. Paurometabolous development occurs in (a) housefly (b) cockroach (c) mosquito (d) moth.

Answer 1. 6. 11. 16. 21. 26.

(a) (c) (b) (d) (d) (a)

2. 7. 12. 17. 22. 27.

(a) (c) (d) (b) (c) (c)

3. 8. 13. 18. 23. 28.

(c) (c) (c) (a) (b) (a)

Key 4. 9. 14. 19. 24. 29.

(b) (b) (b) (d) (c) (b)

5. 10. 15. 20. 25. 30.

(c) (d) (c) (d) (d) (b) 

Drone is latest weapon against cheating in CHINA EXAMS THE LATEST weapon in the fight against cheating on China’s allimportant college entrance exam is a six-propeller drone. The contraption flew over two testing centers in Luoyang city in central China’s Henan province to scan for any unusual signals being sent to devices smuggled by students taking the annual test. No such signals were detected Sunday, the first day of the exam, a Henan province news website said. The drone cost hundreds of thousands of yuan (tens of thousands of dollars) and is as big as a gas station pump when extended, said LanZhigang, from Luoyang’s Radio Supervision and Regulation Bureau. “In an urban area full of tall buildings, various barriers limit the operating range of devices on ground, while the drone can rise up to 1,640 feet and detect signals over the whole city,” Lan said. Almost all Chinese high school graduates must take the test and the scores are the key criterion for which tier of university they can enter. Pressure is immense and many students spend months cramming. Parents travel to the cities where the tests are given to stay with their children during the exam, which can last two or three days. Cheating is common given the high stakes, and methods include selling supposed answers, hiring surrogate test-takers and using wireless equipment to communicate during the test. Courtesy : The Times of India

KCET Karnataka Common Entrance Test

1. Which of the following sentences is correct? (a) In prokaryotes there are no membrane bound cell organelles. (b) Cells of all living organisms have a nucleus. (c) Cells are formed de novo from abiotic materials. (d) Both animal and plant cells have a well defined cell wall.

8. The 2000 year old seed excavated from King Herod’s palace at dead sea belong to (a) Dendrocalamus strictus (b) Lupine articus (c) Phoenix dactylifera (d) Strobilanthus kunthiana. 9. label the correct part of the Myosin monomer.

2. The element responsible for the ring structure of chlorophyll and maintenance of ribosome structure is (a) Ca++ (b) Mg+ (c) S (d) K+. 3. One hormone hastens maturity period in juvenile conifers, a second hormone controls xylem differentiation, while the third increases the tolerance of plants to various stresses. They are respectively (a) Gibberellin, Auxin, Cytokinin (b) Auxin, Gibberellin, Cytokinin (c) Gibberellin, Auxin, ABA (d) Auxin, Gibberellin, ABA. 4. Which of the following is not an ex-situ conservation? (a) Cryopreservation (b) Seed bank (c) Biosphere reserves (d) Botanical garden 5. If 30J of energy is trapped at producer level, then how much energy will be available to peacock as food in the following chain? Plant → Mice → Snake → Peacock (a) 0.3J (b) 0.03J (c) 0.0003J (d) 0.003J 6. With respect to phenylketonuria identify which statement is not correct. (a) It is a case of aneuploidy. (b) It is an example of pleiotropy. (c) Caused due to autosomal recessive trait. (d) It is an error in metabolism. 7. In a human foetus the limbs and digits develop after (a) 12 weeks (b) first trimester (c) 5th month (d) 8 weeks. 82

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(a) (A) (C) (b) (A) (C) (c) (A) (C) (d) (A) (C)

Actin binding site ATP binding site Cross arm Head ATP binding site Head Head Actin binding site

(B) (D) (B) (D) (B) (D) (B) (D)

Head Cross arm Actin binding site ATP binding site Actin binding site Cross arm Cross arm ATP binding site

10. Greenhouse crops such as tomatoes and bell pepper produce higher yields. This is due to (a) CO2 enriched atmosphere leads to higher yields (b) CO2 is a limiting factor to photosynthesis (c) diffused light in green house (d) tomatoes and bell pepper are not C3 plants. 11. The organisms which completely lack a cell wall and can live without oxygen are (a) mycoplasmas (b) archaebacteria (c) methanogens (d) thermoacidophiles. 12. RNA polymerase-I transcribes eukaryotic ribosome which does not consist of (a) 5.8S rRNA (b) 28S rRNA (c) 18S rRNA (d) 5S rRNA. 13. Match the following. (A) VNTR (B) Introns and Exons (C) Dystrophin (D) Satellite DNA

p. q. r. s.

largest gene DNA fingerprinting Bulk DNA Splicing

(a) (b) (c) (d)

(A) - r, (B) - s, (C) - p, (D) - q (A) - q, (B) - s, (C) - p, (D) - r (A) - q, (B) - p, (C) - s, (D) - r (A) - s, (B) - p, (C) - q, (D) - r

14. Smack and Crack are produced from (a) Cannabis sativa and Papaver somniferum (b) Cannabis sativa and Atropa belladonna (c) Erythroxylon coca and Atropa belladonna (d) Papaver somniferum and Erythroxylon coca. 15. Double lines in pedigree analysis show (a) unaffected offspring (b) sex unspecified (c) normal mating (d) consanguineous marriage. 16. Progestasert is an IUD which makes the uterus unsuitable and cervix hostile to the sperms as they are (a) hormone releasing IUDs (b) copper releasing IUDs (c) ideal contraceptive (d) non-medicated IUDs. 17. The chromosome number in meiocyte is 34. The organism could be (a) Ophioglossum (b) dog (c) onion (d) apple. 18. A fall in glomerular filtration rate activates (a) adrenal medulla to release adrenaline (b) juxtaglomerular cells to release renin (c) posterior pituitary to release vasopressin (d) adrenal cortex to release aldosterone. 19. In a 3.2 Kbp long piece of DNA, 820 adenine bases were found. What would be the number of cytosine bases? (a) 780 (b) 1560 (c) 740 (d) 1480 20. Assisted Reproductive Technology does not include (a) Zygote Extra Fallopian Transfer (b) In vitro fertilisation and embryo transfer (c) Artificial insemination (d) Gamete Intra Fallopian Transfer. 21. During menstrual cycle, the cyclical changes take place in (a) perimetrium (b) endometrium (c) corpus Iuteum (d) myometrium. 22. BOD refers to (a) the oxygen required for bacteria to grow in 1 litre of effluent. (b) the amount of oxygen consumed if all the organic matter in 1000 ml of water were oxidised by bacteria (c) the amount of oxygen released if all the organic matter in 1000 ml of water were oxidised by bacteria (d) the amount of oxygen released when all the organic matter was consumed by bacteria in 1 litre of water

23. Sonalika and Kalyan Sona are high yielding varieties of (a) sugarcane (b) rice (c) wheat (d) maize. 24. According to Robert Constanza, 50% of the total cost for ecosystem services goes to (a) nutrient cycling (b) recreation (c) soil formation (d) climate regulation. 25. Choose the correct statement. (a) Oxygen is vital in respiration for removal of hydrogen. (b) Pyruvate is formed in the mitochondrial matrix. (c) There is complete breakdown of glucose in fermentation. (d) During the conversion of succinyl CoA to succinic acid a molecule of ATP is synthesised. 26. Given below is the representation of the extent of global diversity of vertebrates. What groups does the portions represent?

(a) (b) (c) (d)

A Birds Mammals Fishes Fishes

B Reptiles Birds Amphibians Mammals

C Fishes Fishes Mammals Birds

D Mammals Amphibians Birds Reptiles

E Amphibians Reptiles Reptiles Amphibians

27. Select the mismatch pair from the following. (a) Oxytocin – Contraction of uterine muscles (b) Insulin – Gluconeogenesis (c) Prolactin – Milk production in mammary glands (d) Glucagon – Glycogenolysis 28. Which of the following would most likely help to slow down the greenhouse effect? (a) Converting tropical forests into grazing land for cattle. (b) Ensuring that all excess paper packaging is burned to ashes. (c) Redesigning landfill dumps to allow methane to be collected. (d) Promoting the use of private rather than public transport. 29. If an inheritable mutation is observed in a population at high frequency, it is referred to as (a) sequence annotation (b) DNA polymorphism (c) linkage (d) expressed sequence tag. 30. Find the wrongly matched pair. (a) lungs of the planet – Amazon rainforest (b) Endemism – Species confined to one region and also found in other regions (c) Hotspots – Regions with species richness (d) Alien species – Clarias gariepinus MT BIOLOGY

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31. The function of a selectable marker is (a) eliminating transformants and permitting non-transformants (b) identify ori site (c) elimination of non-transformants and permitting transformants (d) to destroy recognition sites. 32. The T-wave in an ECG represents (a) depolarisation of ventricles (b) electrical excitation of atria (c) beginning of systole (d) return of the ventricles from excited state. 33. In prokaryotes the glycocalyx when it is thick is called (a) capsule (b) slime layer (c) cell wall (d) mesosome. 34. Which of the following is not correct in mass flow hypothesis? (a) As hydrostatic pressure in the phloem sieve tube increases pressure flow stops and sap is accumulated in phloem. (b) The sugar is moved bidirectionally. (c) The sugar which is transported is sucrose. (d) loading of the phloem sets up a water potential gradient that facilitates the mass movement in the phloem. *35. Identify this structure. (a) Adenylic acid (b) Uracil (c) Cholesterol (d) Adenosine 36. In 125 amino acid sequence if the codon for 25th amino acid is mutated to UAA, then (a) a polypeptide of 24 amino acids is formed (b) a polypeptide of 124 amino acids is formed (c) no polypeptides are formed (d) a polypeptide of 25 amino acids is formed. 37. Three copies of chromosome – 21 in a child with Down’s syndrome have been analysed using molecular biology technology to detect any possible DNA polymorphism with reference to different alleles located on chromosome – 21. Results showed that out of 3 copies 2 of the chromosomes of the child contain the same alleles as one of the mother’s alleles. Based on this when did the non-disjunction event most likely occur? (a) Paternal meiosis-I (b) Maternal meiosis-I (c) Paternal meiosis-II (d) Maternal meiosis-II 38. Which of the following is not correct with respect to malaria? (a) RBCs rupture and release haemozoin which causes chills. (b) Sporozoites multiply in blood. (c) Female Anopheles mosquito is the vector. (d) Malignant malaria is caused by Plasmodium falciparum. 39. Ernst Chain and Howard Florey’s contribution was (a) establishing the potential of penicillin as an effective antibiotic (b) discovery of streptokinase

(c) production of genetically engineered insulin (d) discovery of DNA sequence. 40. Choose the correct combination of labelling the molecules involved in the pathway of anaerobic respiration in yeast.

(a) (b) (c) (d)

A A A A

- Acetaldehyde, B - CO2, C - Ethanol - Ethanol, B - CO2, C - Acetaldehyde - Ethanol, B - Acetaldehyde, C - CO2 - CO2, B - Ethanol, C - Acetaldehyde

41. The breakdown of detritus into small particles by detritivores is called (a) leaching (b) humification (c) fragmentation (d) catabolism. 42. The formation of two species from one ancestral species is known as (a) convergent evolution (b) phyletic evolution (c) allopatry (d) divergent evolution. 43. A scrubber in the exhaust of a chemical industrial plant removes (a) gases like ozone or methane (b) gases like sulphur dioxide (c) gases like nitrous oxide (d) particulate matter of the size 5 micrometers or above. 44. With respect to DNA fragmentation Statement A : Gel electrophoresis and elution are two important processes. Statement B : After staining with ethidium bromide it has to be exposed to U.V. light. (a) Only A is correct. (b) Both A and B are correct statements. (c) Only B is correct. (d) Only A is correct and B is not correct. 45. The pioneer species in xerarch and hydrarch succession are respectively (a) lichens and phytoplanktons (b) lichens and sedges (c) phytoplanktons and lichens (d) lichens and rooted hydrophytes. 46. Hibernating animals have tissues containing mitochondria with a membrane protein that accelerates electron transport while blocking the synthesis of ATP. What is the consequence of this? (a) Hibernating animals can synthesise fat instead of wasting energy of respiration. *Original question incorrectly framed

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Statement Y : It is an indigenous species of our country. (a) Only statement X is correct and y is wrong. (b) Both statements X and y are correct. (c) Only statement y is correct and X is wrong. (d) Both statements X and y are wrong.

(b) Energy is saved because glycolysis and the citric acid cycle shuts down. (c) Pyruvate is converted to lactic acid by anaerobic fermentation. (d) The energy of respiration is converted into heat. 47. Which of the following conditions correctly describes the manner of determining the sex in the given example? (a) Homozygous sex chromosome XX produces male in Drosophila. (b) XO type of sex determines male sex in grasshopper. (c) Homozygous sex chromosome ZZ determines female sex in birds. (d) XO condition in humans as found in Klinefelter’s syndrome determines female sex. 48. Natural killer lymphocytes are an example for (a) physical barrier (b) cytokine barrier (c) cellular barrier (d) physiological barrier. 49. The codon AUG has dual function. It is an initiation codon and also codes for (a) phenylalanine (b) formaldehyde (c) serine (d) methionine. 50. Identify the wrong statement. (a) Alleles b and c also produce sugar. (b) Alleles IA and IB produce sugars. (c) When IB and b or i are present only IB is expressed. (d) Both IA and IB are present together and they express because of co-dominance. 51. Continued self pollination results in (a) formation of unisexual flowers (b) inbreeding depression (c) gametes loose vigour (d) self incompatibility. 52. Which vector can clone a small fragment of DNA? (a) Plasmid (b) Bacterial artificial chromosome (c) Cosmid (d) yeast artificial chromosome 53. Seeds without fertilisation are obtained from (a) polyembryony (b) parthenocarpy (c) dormancy (d) apomixis. 54. With respect to Eichhornia: Statement X : It drains off oxygen from water and is seen growing in standing water.

ANSWERS

WHO AM I ...

1.

Pollen Mother Cell (PMC)

Pg. 52

2.

Synergid

Pg. 57

3.

Nereis

Pg. 66

4.

Nymph

Pg. 74

5.

Clitellum

Pg. 76

55. Identify the Phylum X. ANIMALIA

TISSSUE GRADE

BILATERAL

ACOELOMATE

X

(a) Hemichordata (b) Aschelminthes (c) Platyhelminthes (d) Ctenophora 56. During sewage treatment biogas produced includes (a) hydrogen sulphide, nitrogen, methane (b) methane, oxygen, hydrogen sulphide (c) methane, hydrogen sulphide, carbon dioxide (d) hydrogen sulphide, methane, sulphur oxide. 57. The ancestors of modern day frogs and salamanders are (a) Icthyophis (b) jawless fish (c) Amphioxus (d) Coelacanth. 58. Hisardale is obtained by crossing (a) horse with donkey (b) Merino ewes with Bikaneri rams (c) superior bull with superior cow (d) Bikaneri ewes with Merino rams. 59. The nitrogen base found only in DNA is also called (a) uracil (b) 5-methyl uracil (c) guanine (d) NH4Cl. 60. The hormone which acts on Sertoli cells and stimulates the process of spermiogenesis is (a) GnRH (b) androgen (c) FSH (d) lH. 1. 6. 11. 16. 21. 26. 31. 36. 41. 46. 51. 56.

(a) (a) (a) (a) (b) (d) (c) (a) (c) (d) (b) (c)

2. 7. 12. 17. 22. 27. 32. 37. 42. 47. 52. 57.

Answer

Key

3. 8. 13. 18. 23. 28. 33. 38. 43. 48. 53. 58.

4. 9. 14. 19. 24. 29. 34. 39. 44. 49. 54. 59.

(b) (d) (d) (d) (b) (b) (d) (b) (d) (b) (a) (d)

(c) (c) (b) (b,d) (c) (c) (a) (b) (b) (c) (d) (d)

MT BIOLOGY

(c) (d) (d) (a) (c) (b) (a) (a) (b) (d) (a) (b)

TODAY | JUly ‘15

5. 10. 15. 20. 25. 30. 35. 40. 45. 50. 55. 60.

(b) (a) (d) (a) (a) (b) (b) (c) (a) (a) (None) (c)  85

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