Class 10 Life Process

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Class X, NCERT (CBSE) Science Chapter 6, LIFE PROCESSES

Extrascore Study Materials NUTRITION All living organisms require energy to carry on various maintenance processes. This energy comes from the outside the body of the individual organism. Some organism utilize simple inorganic substances such as carbon dioxide and water, whereas other organisms utilize complex substances which are required to be digested before they can be utilized for various life processes such as growth, maintenance and repair. So, “Nutrition” is a process by which a source of energy from outside the body of the organism, which we call food, is transferred to inside the body of the organism.

MODES OF NUTRITION There are two modes of nutrition - Autotrophic and Heterotrophic. Autotrophic Nutrition - In this type of nutrition food is synthesized by the organism itself (autotrophs) from simple inorganic raw materials such as CO2 and H2O. The essential elements of Autotrophic Nutrition are the presence of green pigment (Chlorophyll) and Sunlight. All green plants and some bacteria have this type of nutrition. Heterotrophic Nutrition - Some organisms are unable to synthesize their own food. These organisms rather obtain their food directly or indirectly from autotrophs. This food is then broken down with the help of some enzymes. This mode of nutrition is called „Heterotrophic Nutrition‟. In this type of nutrition no pigment or sunlight is required. All animals, fungi and some bacteria have this type of nutrition.

PHOTOSYNTHESIS Photosynthesis is the process by which chlorophyll-containing cells in plants synthesize food in the form of carbohydrates, carbon dioxide and water using sunlight. The raw materials required for photosynthesis are carbon dioxide and water and the products formed are carbohydrates and oxygen. The process can be represented as:

The process of photosynthesis occurs in two phases 1. Light Reactions : This reaction takes place in the presence of light. Events occuring during Light Reactions are a. absorption of light energy by chlorophyll molecules. b. splitting of water molecules into hydrogen and oxygen atoms. c. formation of ATP and NADPH2 2. Dark Reactions : This reaction does not require direct light and occurs in the stroma of the chloroplasts. During this phase, reduction of CO2 takes place to form carbohydrates.

NUTRITION IN AMOEBA

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Fig - Nutrition in Amoeba

Amoeba takes in food using temporary finger-like extensions of the cell surface, calledpseudopodia, which fuse over the food particle forming a food - vacuole. Inside the food vacuole, complex substances are broken down into simpler ones which then diffuse into the cytoplasm.

NUTRITION IN HUMAN BEINGS

Fig - Human Alimentary Canal Eating nutritious food is healthy because it supplies essential nutrients required to sustain life. It is by the process of digestion that the nutrients present in the food are utilized by the human body. The following are the different digestive organs and their functions MOUTH Digestion of food begins in the mouth. It comprises of the following parts Teeth: Tear and break down the food. Saliva: Contains a digestive enzyme called salivary amylase, which help to break down starch into sugar. Tongue: It is a sense organ with taste buds. Its muscular movements help to move the food from the mouth into inside. PHARYNX

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It opens into the oesophagus (which leads to the stomach) and trachea (which leads to the lungs). Pharynx is a common passageway for food and air. OESOPHAGUS The peristaltic movements of the longitudinal smooth muscles in oesophagus push the food into the stomach and also prevent the chewed food material from moving back into the mouth. STOMACH The stomach stores and mixes the food from oesophagus with the gastric juice. The main components of gastric juice, which is secreted by gastric glands present in the walls of the stomach, are HCl, mucus, and pepsynogen. SMALL INTESTINE 1. It is the longest part of the elementary canal and is made up of three parts - duodenum, jejunum, and ileum. 2. The length of the small intestine depends on the type of food consumed by the organism and hence, differ ijn various animals. 3. It also produces intestinal juice from glands present in the wall which helps in further digestion of the food. 4. Other digestive juices like - bile juice (which causes emulsification of fats) and thepancreatic juice (for digesting proteins and emulsified fats) mix with the food in the small intestine. 5. The small intestine is the site for complete digestion of carbohydrates, proteins and fats. 6. The digested food is then absorbed through the intestinal walls and transported to the various parts of the body. LARGE INTESTINE The indigestible material and water enters the large intestine. The large intestine performs the function of storage of wastes (faeces) before they are excreted from the body via the anus.

ATP The energy released during the process of respiration is used to form high energy ATP (adenosine triphosphate) molecules. ATP is known as energy currency of the cell and it is used as cellular fuel for most cellular processes. ATP is called „energy currency‟ of the cell because the energy required for various life activities is released by mitochondria in the form of ATP molecules, which is used by the body performing various activities. For example, energy stored in ATP is used to bring about energy requiring activities of cell such as photosynthesis, protein synthesis and muscle contraction.

LYMPHATIC SYSTEM Lymph is another fluid connective tissue, which helps in the process of transportation. Some pores are present in the walls of the capillaries and through these pores, small amounts of plasma, proteins, and blood cells escaped into the intercellular spaces in the tissues to form the tissue fluid or lymph. It is similar to the plasma of blood but colourless and contains less protein. Lymph drains into lymphatic capillaries from the intercellular spaces, which joined to form large lymph vessels. Functions of the Lymph: 1. It acts as a reservoir of water, salts and digested food. 2. It carries digested food and fats from the small intestine. Lymphatic vessels present in theintestinal villi absorb fatty acids. 3. It contains phagocytes that can engulf and destroy bacteria. and other foreign particles.

FUNCTION OF KIDNEYS

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Kidneys form a part of human excretory system. Different functions of kidneys are as follows: 1. Kidneys filter waste products from the blood e.g. various nitrogenous wastes such as urea, uric acid etc. 2. Kidneys play an important role in the formation of urine. 3. It helps us in maintaining the water balance of our body by removing excess fluids. 4. It is the basic filtration unit of the excretory system. 5. They also make hormones that keep the bones strong and healthy.

MECHANISM OF URINE FORMATION

Structure of Nephron Nephron is the filtration unit of kidney. It consists of a tubule which is connected with collecting duct at one end and a cup - shaped structure at the other end. This cup-shaped structure is called „Bowman‟s capsule‟. Every Bowman‟s capsule contains a cluster of capillaries, called „Glomerulus‟, within the cup - shaped structure. The blood enters into Glomerulus through afferent arteriole of renal artery and leaves it through efferent arteriole. Functioning of Nephron 1. Filtration: Filtration of blood takes place in Bowman‟s capsule from the capillaries of glomerulus. The filtrate passes into the tubular part of the nephron. This filtrate contains glucose, amino acids, urea, uric acid, salts and a major amount of water. 2. Re-absorption: As the filtrate flows along the tubule useful substances such as glucose, amino acids, salts and water are selectively re-absorbed into the blood by capillaries surrounding the nephron tubule. The amount of water re-absorbed depends on the need of the body and also on the amount of wastes to be excreted. 3. Urine: The filtrate which remains after re-absorption is called urine. Urine contains dissolved nitrogenous waste, i.e. urea and uric acid, excess salts and water. Urine is collected from nephrons by the collecting duct to carry it to the ureter. EXCRETION IN PLANTS To get rid of excretory products, plants use the following ways: (1) Many waste products are stored in vacuoles of the cells. Plant cells have comparatively large vacuoles. (2) Some waste products are stored in the leaves. They are removes as the leaves fall off.

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(3) Some waste products such as resins and gums are stored, especially in non-functional old xylem. (4) Some waste products such as tannins, resins, gums are stored in bark, thereby removed as peeled off. (5) Plants also excrete some waste products through roots into the soil around them. (6) Plants get rid of excess water through transpiration. TRANSPORTAION IN PLANTS The main components of transport system in plants are: 1. Xylem, 2. Phloem. Xylem - It consists of vessels and tracheids. Xylem helps to conduct water and minerals from soil to the leaves. Phloem - It consists of sieve tubes and companion cell. Phloem helps to transport food materials from leaves to various parts of the plant. This process is called translocation. Transportation of Minerals Water and minerals are transported through xylem cells from soil to the leaves. The xylem cells of roots stem and leaves are interconnected to form a conducting channel that reaches all parts of the plant. The root cells take ions from the soil. This creates a difference between the concentration of ions of roots and soil. Therefore, there is a steady movement of water into xylem. An osmotic pressure is formed and water and minerals are transported from one cell to the other cell due to osmosis. The continuous loss of water takes place due to transpiration. Because of transpiration, also a suction pressure is created as a result of which water is forced into the xylem cells of roots. The effect of root pressure for transportation in plants is more important in night while during day time transpiration pull becomes the major driving force. Transportation of Water The prepared food is transported in the plants through phloem to the storage organs of roots, fruits, seeds and growing parts. This process is called translocation. This function is done by sieve tubes and companion cells. The movement of food particles takes place upward and downward. Mechanism of translocation is an active process that utilizes energy. Materials are transferred from leaf cells or from the site of storage into phloem tissue. For this energy is required which is provided by the ATP molecules. This energy increases the osmotic pressure, as a result, water from outside moves into the phloem. This pressure maintains the movement of food through all the parts of plants.

Sample Questions Q.1: Which pigment captures solar energy? Ans: Chlorophyll Q.2: Name any three life processes. Ans: Nutrition, respiration and blood circulation Q.3: Answer the following questions: (i) What is the first reaction in photosynthesis? (ii) In which form do plants store food? Ans: (i) The first reaction in photosynthesis is the photolysis of water. (ii) The product of photosynthesis is glucose, which is stored in plants in the form of starch. Q.4: What are the inorganic sources used by plants for making food?

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Ans: Carbon dioxide, water and sunlight. Q.5: What are the outside raw materials used by an organism? Ans: Various outside raw materials used by an organism are as follows: 1. Food as a source of supplying energy and materials. 2. Oxygen for the break-down of the food to obtain energy. 3. Water for proper digestion of food and other functions inside the body. The raw materials required by an organism will vary depending on the complexity of the organism and its environment. Q.6: Plants have lower energy need and relatively slow transportation system than those of animals.Givereasons.? Ans: Energy needs differ between different body designs. Unlike animals, plants do not move and plant bodies have also a large proportions of dead cells in many tissues. As a result, plants have lower energy needs and also relatively slow transportation than those required by animals. Q.7: Briefly describe the digestive functions of liver and pancreas. Ans: Liver : 1. The liver secretes bile which is stored in the gall bladder from where it is sent to the duodenum whenever needed. 2. The bile breaks down the fat droplets into small fat globules. This phenomenon is known as emulsification of the fat. Pancreas : 1. Pancreas secretes a juice which is sent to the duodenum. 2. Pancreatic juice contains different enzymes. The Trypsin, which digests proteins into peptones, and the pancreatic amylase, which digests starch into sugar. The lipase which breaks down the emulsified fats. 3. It also produces hormones - insulin and glucagon. This insulin is a very important hormone that regulates the sugar level in blood. Q.1: Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans? Ans: Multicellular organisms such as humans possess complex body structure. They have specialized cells and tissues for performing various necessary functions of body. Unlike the unicellular organisms in multicellular organisms, all the cells are not in direct contact with surrounding environment. Therefore, simple diffusion will not meet the oxygen requirement of all the cells. Q.2: What criteria do we use to decide whether something is alive? Ans: Any visible movement of various types such as walking, breathing or growing can be taken as an indication of life. However a living organism can also have movements which are not visible to the naked eye. So, the presence of life process is the fundamental criteria that are used to decide whether something is alive or not. Q.3: What are outside raw materials used by an organism? Ans: Various outside raw materials used by an organism are as follows: a. Food as source of supplying energy and materials. b. Oxygen for breakdown of food to obtain energy. c. Water for proper digestion of food and other functions inside the body.

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The raw materials required by an organism will vary depending on the complexity of the organism and its environment. Q.4: What processes would you consider essential for maintaining life? Ans: There are various life processes which are essential for maintaining life. Some of them are as follows: a. Nutrition b. Respiration c. Excretion d. Transportation

(Page 101) Q.1: What are the differences between autotrophic nutrition and heterotrophic nutrition? Ans: Autotrophic Nutrition

Heterotrophic Nutrition

1. Food is synthesized from simple inorganic 1. Food is obtained directly or indirectly raw materials such as CO2and water. from autotrophs. This food is broken down with the help of enzymes. 2. Presence of green pigment (chlorophyll) is necessary. 2. No pigment is required in this type of nutrition. 3. Food is generally prepared during day time. 3. Food can be prepared at all times. 4. All green plants and some bacteria have this type of nutrition.

4. All animals and fungi have this type of nutrition.

Q.2: Where do the plants get each of the raw materials required for photosynthesis? Ans: Plants need the following things for photosynthesis: Carbon Dioxide - Plants get CO2 from atmosphere through stomata. Water - Plants absorb water from soil through roots and transport to leaves. Sunlight - Sunlight, which is absorbed by the chlorophyll and other green parts of the plant. Q.3: What is the role of acid in our stomach? Ans: Roles of acid in our stomach are 1. It makes an acidic medium in our stomach which is necessary for activation of pepsin enzyme. 2. It kills germs present in the food. Q.4: What is the function of digestive enzymes?

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Ans: The food materials are very complex in nature. Digestive enzymes such as, amylase, lipase, pepsin, Trypsin etc. Help to break these complex molecules into smaller moleculesso that they can be absorbed by the walls of small intestine. Q.5: How is the small intestine designed to absorb digested food? Ans: Small intestine is designed to more and more area for absorption of digested food and transfer into the blood for circulation throughout the body. The inner lining of small intestine has a large number of finger-like projections called villi. These villi provide a large surface area for absorption of food. These villi are richly supplied with blood vessels which take the absorbed food to each and every cell of the body, where it is used for obtaining energy, building up new tissues and repairing of old tissues. (Page 105) Q.1: What advantage over an aquatic organism does a terrestrial organism have with regard to obtain oxygen for respiration? Ans: The organisms that live in water use oxygen dissolved in surrounding water. Since, air dissolved in water has fairly low concentration of oxygen, the aquatic organisms has much faster rate of breathing. Terrestrial organisms take oxygen from the oxygen - rich atmosphere through respiratory organs. So, they have much less breathing rate than aquatic organism. Q.2: What are the different ways in which glucose is oxidized to provide energy in various organisms? Ans: First step of breakdown of glucose (6 carbon molecules) takes place in the cytoplasm of cells of all organisms. This process yields a 3 carbon molecule compound called pyruvate. Further break down of pyruvate takes place in different manners in different organisms.

1. Anaerobic Respiration This process takes place in absence of oxygen, e.g. in yeast during fermentation. In this case pyruvate is converted into ethanol and carbon dioxide. 2. Aerobic Respiration In aerobic respiration, breakdown of pyruvate takes place in presence of oxygen to give rise 3molecules of carbon dioxide and water. The release of energy in aerobic respiration is much more than anaerobic respiration. 3. Lack of Oxygen

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Sometimes, when there is lack of oxygen, especially during vigorous activity, in our muscles, pyruvate is converted into lactic acid (3 carbon molecule compounds). Formation of lactic acid in muscles causes cramp. Q.3: How are oxygen and carbon dioxide transported in human beings? Ans: (a) Transport of Oxygen The respiratory pigments (haemoglobin) present in red blood cells takes up the oxygen from the air to the lungs. They carry the oxygen to tissues which are deficient in oxygen. (b) Transport of carbon dioxide Carbon Dioxide is more soluble in water. Hence, it is mostly transported from body tissues in the dissolved form in our blood plasma to lungs where it diffuses from blood to air in the lungs and then expelled out through nostrils. Q.4: How are lungs designed in human beings to maximize the area for exchange of gases? Ans: In the lungs, the air passage (wind pipe) divides into smaller tubes, called „bronchi‟ in turn form „bronchioles‟. The bronchioles which terminate in balloon - like structures, are called „alveoli‟. Each lung contains 300 - 350 million alveoli. The alveoli present in the lungs provide maximum surface for exchange of gases. The alveoli have very thin walls and contain an extensive network of blood vessels to facilitate exchange of gases. (Page 110) Q.1: What are the components of the transport system in human beings? What are thefunctions of these components? Ans: The main components of the transport system in human beings are the heart, blood and blood vessels. Functions: Heart - Heart is a pumping organ to push and pull blood around the body. It receives the deoxygenated blood from various parts of the body and sends this impure blood to lungs for oxygenation. Again after receiving pure blood from lungs it sends this oxygenated blood throughout the body. Blood - It is a fluid connective tissue. It consists of: (a) plasma, (b) RBC, (c) WBC, and (d) blood platelets. Plasma transports food, CO2 and nitrogenous wastes in dissolved form. RBC transports respiratory gases and hormones. WBC protects the body from infections and platelets prevent the loss of blood at the time of injury by forming blood clots. Blood vessels - There is a network of blood vessels which contain arteries, veins and capillaries. They help in the circulation of blood throughout the body. Q.2: Why is it necessary to separate oxygenated and deoxygenated blood in mammals and birds? Ans: It is necessary to separate oxygenated and deoxygenated blood to maintain efficient supply of oxygen into the body. This system is essential in animals that have high energy need. For example, animals like mammals and birds which constantly use this energy to maintain their body temperature. Q.3: What are the components of the transport system in highly organized plants? Ans: The main components of transport system in plants are: 1. Xylem, 2. Phloem. Xylem - It consists of vessels and tracheids. Xylem helps to conduct water and minerals from soil to the leaves. Phloem - It consists of sieve tubes and companion cell. Phloem helps to transport food materials from leaves to various parts of the plant. This process is called translocation. Q.4: How are water and minerals transported in plants?

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Ans: Water and minerals are transported through xylem cells from soil to the leaves. The xylem cells of roots stem and leaves are interconnected to form a conducting channel that reaches all parts of the plant. The root cells take ions from the soil. This creates a difference between the concentration of ions of roots and soil. Therefore, there is a steady movement of water into xylem. An osmotic pressure is formed and water and minerals are transported from one cell to the other cell due to osmosis. The continuous loss of water takes place due to transpiration. Because of transpiration, also a suction pressure is created as a result of which water is forced into the xylem cells of roots. The effect of root pressure for transportation in plants is more important in night while during day time transpiration pull becomes the major driving force. Q.5: How is the food transported in plants? Ans: The prepared food is transported in the plants through phloem to the storage organs of roots, fruits, seeds and growing parts. This process is called translocation. This function is done by sieve tubes and companion cells. The movement of food particles takes place upward and downward. Mechanism of translocation is an active process that utilizes energy. Materials are transferred from leaf cells or from the site of storage into phloem tissue. For this energy is required which is provided by the ATP molecules. This energy increases the osmotic pressure, as a result, water from outside moves into the phloem. This pressure maintains the movement of food through all the parts of plants. (Page 112) Q.1: Describe the structure and functioning of nephron. Ans:

Structure of Nephron Nephron is the filtration unit of kidney. It consists of a tubule which is connected with collecting duct at one end and a cup - shaped structure at the other end. This cup-shaped structure is called „Bowman‟s capsule‟. Every Bowman‟s capsule contains a cluster of capillaries, called „Glomerulus‟, within the cup - shaped structure. The blood enters into Glomerulus through afferent arteriole of renal artery and leaves it through efferent arteriole. Functioning of Nephron 1. Filtration: Filtration of blood takes place in Bowman‟s capsule from the capillaries of glomerulus. The filtrate passes into the tubular part of the nephron. This filtrate contains glucose, amino acids, urea, uric acid, salts and a major amount of water. 2. Re-absorption: As the filtrate flows along the tubule useful substances such as glucose, amino acids, salts and water are selectively re-absorbed into the blood by capillaries surrounding the nephron tubule. The amount of water re-absorbed depends on the need of the body and also on the amount of wastes to be excreted.

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3. Urine: The filtrate which remains after re-absorption is called urine. Urine contains dissolved nitrogenous waste, i.e. urea and uric acid, excess salts and water. Urine is collected from nephrons by the collecting duct to carry it to the ureter. Q.2: What are the methods used by plants to get rid of excretory products? Ans: To get rid of excretory products, plants use the following ways: (1) Many waste products are stored in vacuoles of the cells. Plant cells have comparatively large vacuoles. (2) Some waste products are stored in the leaves. They are removes as the leaves fall off. (3) Some waste products such as resins and gums are stored, especially in non-functional old xylem. (4) Some waste products such as tannins, resins, gums are stored in bark, thereby removed as peeled off. (5) Plants also excrete some waste products through roots into the soil around them. (6) Plants get rid of excess water through transpiration. Q.3: How is the amount of urine produced regulated? Ans: The amount of urine produced depends on the amount of excess water and dissolved wastes present in the body. When excess water in the body is more, large quantities of dilute urine is excreted out. On the other hand if the excess water is less, a small quantity of concentrated urine is excreted. When there is more quantity of dissolved wastes in the body, more quantity of water is required to excrete them. As a result of which, the urine produced increases. Some other factors such as habitat of an organism and hormone such as Anti-diuretic hormone (ADH) also regulates the amount of urine produced. ---**---**---**--(Please Note: Students are suggested to compare all the topics with that of NCERT. The Question given here covers all the important topics.)

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