Biology Today - May 2016

55

Vol. XVIII

No. 5

21

May 2016

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71

CONTENTS

8 48

8

PMT Essential (XI)

Morphology of Flowering Plants-II

46

44

21 Target AIIMS

Practice Questions 2016

25 High Yield Facts-Zoology

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Assertion & Reason : Biomolecules, Microbes in Human Welfare

Mathematics Today Chemistry Today Physics For You Biology Today

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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.

MORPHOLOGY OF FLOWERING PLANTS-II INFLORESCENCE The arrangement and mode of distribution of flowers on the shoot system of a plant is called inflorescence. The common axis bearing the flowers is called peduncle. Stalk of the individual flower is called pedicel. Flowers develop on the peduncle in the axis of bracts. The different types of inflorescence are :

Solitary Flowers occur singly or are separated from other flowers of the same plant by means of vegetative regions. It is of following types: (i) Solitary terminal : Single flower on terminal part of the branch HJ, Poppy (ii) Solitary axillary : Single flower in the axil of leaf,HJ+LELVFXV

Racemose An indeterminate type of inflorescence with indefinite growth.The arrangement of flowers on peduncle is either acropetal (LHyounger towards the apex and older towards the base) or centripetal LH younger towards the centre and older towards the periphery). 8

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Fig.: Solitary inflorescence of +LELVFXV

Simple Racemose (Peduncle is unbranched) Typical raceme Pedicellate bisexual flowers arranged in acropetal succession HJ%UDVVLFD.

Corymb Older flowers have longer pedicel and younger flowers have shorter pedicel. As a result all the flowers are brought to the same level HJ,EHULV

Spikelets Spikelets are small and few flowered spikes which are surrounded at the base by two scales or glumes HJ Family Gramineae (= Poaceae). Capitulum or Racemose head The flattened peduncle called as receptacle bears numerous small sessile flowers called as florets arranged in a centripetal fashion. Florets can be ray florets (unisexual, ligulate, sessile, strap shaped, petaloid, zygomorphic flowers arranged on the periphery of receptacle) or disc florets (tubular, bisexual, sessile, actinomorphic flowers occupying central position on the receptacle).

Spike Sessile flowers arranged in acropetal succession HJ&DOOLVWHPRQ$FK\UDQWKHV

Umbel All the pedicellate flowers arise from a single point in a centripetal fashion. The peduncle is very much reduced, HJ +\GURFRW\OH 3UXQXV.

Catkin Pendulous unisexual spike which bears naked pistillate or staminate flowers HJ 0RUXV DOED3RSXOXVHWF

Spadix Spike with fleshy peduncle and having both male and female flowers. It is surrounded by a large green or coloured bract called spathe. The two types of flowers are separated by downwardly directed sterile hair or neuter flowers, HJ&RORFDVLD$UXP.

Spathe Sterile portion of spadix Male flowers Neuter flowers Female flowers

Corymbose raceme The young flowers appear to be arranged like a corymb but in mature state, the longer pedicels of the lower flowers do not bring them to the level of upper ones, HJ, mustard.

Compound Racemose An indefinite or indeterminate inflorescence in which the peduncle is branched repeatedly once or twice in a racemose fashion. It can be Panicle HJ 'HORQL[, &DVVLDILVWXOD Compound corymb HJ%UDVVLFDROHUDFHD var. ERWU\WLV (cauliflower), Compound umbel HJ., )RHQLFXOXPYXOJDUH, &RULDQGUXPVDWLYXP etc., Compound spike HJ., $PDUDQWKXV, wheat, Compound spadix HJ &RFRV, date palm or Compound capitulum HJ(FKLQRSV, 6SKDHUDQWKXV. Compound spadix of coconut

Cymose

Compound umbel

A determinate inflorescence where main axis (peduncle) terminates into a flower and further growth takes place by lateral branches. The arrangement of flowers is basipetal (LH, younger towards the base and older towards the apex) or centrifugal, (LH, younger towards the periphery and older towards the centre). It is of following types: (i) Uniparous or monochasial cyme A single lateral branch arises from the peduncle of old flower which terminates in a flower. The lateral branch also terminates in a flower. It is of two types: (a) Helicoid cyme – All the flowers are borne on the same side forming a sort of helix, HJ 'URVHUD%HJRQLD0\RVRWLV. (b) Scorpioid cyme - Flowers are alternately borne on both the sides, HJ7HFRPD5DQXQFXOXV+HOLRWURSLXP. 10

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Helicoid cyme

(ii) Biparous or dichasial cyme The main axis terminates in a flower. A pair of lateral branches arise below the terminal flower which too, terminate into a flower. The process is repeated several times, HJ,[RUD, 6DSRQDULD, 'LDQWKXV, jasmine, etc. (iii) Multiparous or polychasial cyme More than two lateral branches continue the growth of inflorescence when the parent axis ends in a flower, HJ+DPHOLD&DORWURSLV. Dichasial cyme

(iv) Cymose head of Dianthus Sessile or subsessile flowers are borne centrifugally around a receptacle, HJ$OEL]]LD$QWKRFHSKDOXVFDGDPED$FDFLD.

Polychasial cyme of Hamelia

Cymose head of Acacia

(v) Scapigerous head The leafless flowering axis known as scape bears clusters of flowers that form a head which is covered by spaths, HJ$OOLXPFHSD.

Hypanthodium The receptacle (peduncle) is fleshy and forms hollow structure with an apical opening (orifice) guarded by hairy structures. Three types of flowers develop on the inner surface of the receptacle. The female flowers are towards the base, male flowers are towards the orifice and the short styled sterile female flowers (gall flowers) are present in between, HJ., )LFXVUHOLJLRVD (peepal), )LFXVEHQJKDOHQVLV (banyan), )LFXV FDULFD(fig). Hypanthodium of fig

Special Inflorescence Verticillaster A modified condensed d i c h a s i a l c y m e l i ke inflorescence in which two whorls of 3 to 9 flowers are borne in dichasial cyme like manner on either side of a node, HJ 2FLPXP VDQFWXP.

Verticillaster inflorescence of Ocimum

Cyathium The inflorescence looks like a flower. The bracts or the involucre become fused to form a cup shaped structure. The inflorescence contains pedicellate, achlamydeous, unisexual flowers of both the types, male and female. The cup encloses a single female flower surrounded by a large number of male flowers. (J(XSKRUELDSXOFKHUULPD.

Cyathium of Euphorbia Cyathium of Euphorbia

Mixed Two or more types of inflorescence get mixed up. It is of following types: (i) Mixed panicle HJ., /LJXVWUXPYXOJDUH,(ii) Panicle of spikelets, HJ., 2U\]DVDWLYD (rice), (iii) Corymb of capitula HJ., $JHUDWXPFRQ\]RLGHV, (iv) Mixed spadix HJ., EDQDQD and (v) Thyrsus HJ. grapevine. s Capitulums are of two types YL]., homogamous and heterogamous :

Homogamous head – The head/capitulum consists of only one type of florets HJ=LQQLD&KU\VDQWKHPXP – all ray florets; 9HUQRQLD1RWRQLD – all disc florets. s Heterogamous head – The head/capitulum consists of different types of florets HJ7ULGD[ +HOLDQWKXV &RVPRV. In the heterogamous heads, ray florets are towards the periphery and disc florets are at the centre of the inflorescence. The inflorescence becomes conspicuous and attractive due to the brightly coloured ray florets. s Head inflorescence (or capitulum) is considered to be the highly evolved type of inflorescence because there is: – Economy of biological materials – Enhancement of attraction due to aggregation of florets – Maximum protection of flowers is ensured – A single visit of the insect can pollinate many flowers s

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FLOWER It is a specialised condensed shoot meant for carrying out the sexual reproduction. It bears floral leaves and gives rise to seeds and fruits. The study of flowers is called anthology. Stamen is the male reproductive part of a flower. It is made up of two parts, a stalk like filament and a knob like terminal anther. Each anther has two lobes which are attached at the back by a sterile band called connective.

They constitute the upper accessory whorl of floral organs called corolla which is brightly coloured to attract insects for pollination. In a petal, the lower part is usually narrow and is termed as claw whereas the expanded portion of the petal is called limb.

Stamen

Carpel or female reproductive part forms the innermost whorl of a flower. The free occurring unit of gynoecium is called pistil, which consists of basal swollen ovary, a stalk like style and a terminal receptive part called stigma.

Carpel

Stigma

Style

Anther

Ovary

Filament

Petal

Thalamus is a modified branch, that represents the axis of the floral whorls with undeveloped or suppressed internodes between them.

Sepal

Ovule Thalamus

They constitute the lower accessory whorl of mostly green, flattened or foliaceous floral organs called calyx which is mainly meant for protecting other floral parts in the bud condition.

s In some flowers, the thalamus becomes elongated showing distinct nodes and internodes, HJ., in *\QDQGURSVLV, &DSSDULV,

etc. s A floral bud like a vegetative bud is either terminal or axillary in position. s Arrangement of sepals, petals, stamens and pistil, etc., on the thalamus is the same as that of the leaves on the stem or

A flower can be

the branch, LH., alternate, opposite or whorled. Bisexual Both the essential organs are present

Neuter Both the essential organs are absent

Pistillate Only female flowers are present Unisexual Only one of the two essential organs is present

Staminate Only male flowers are present

A plant can be (i) monoecious - if male and female flowers develop on the same plant HJmaize, castor or (ii) dioecious - if male and female flowers borne on separate plants HJ., mulberry, date palm. s When male and bisexual flowers are present on the same plant it is called andromonoecious HJ9HUDWUXP. s When female and bisexual flowers are present on the same plant it is called gynomonoecious HJ plants with

heterogamous head inflorescence in Family Asteraceae.

FLORAL SYMMETRY The arrangement of floral organs around the axis of a flower is known as floral symmetry. The shoot on which the flower is borne is called mother axis. The side of the mother axis is posterior while the side of the bract is anterior. In terminal flowers, a distinction into anterior and posterior sides is absent. 12

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Zygomorphic flower It can be divided into two equal halves by only one vertical division, HJ, pea, 2FLPXP

On the basis of floral symmetry

Actinomorphic flower It can be divided by any vertical plane into two equal and similar halves, HJ mustard, &DWKDUDQWKXVURVHXV.

Heteromerous Number in all the whorls is neither the same nor any multiple.

On the basis of number of floral parts

Asymmetrical flower It cannot be divided into two equal halves by any vertical plane, HJ&DQQD.

Isomerous Whorls have equal number of parts or number in one whorl is multiple of the number of other whorl. It can be bimerous (floral part in 2 or multiple of 2), trimerous (floral parts in 3 or multiple of 3), tetramerous (floral parts in 4 or multiple of 4) or pentamerous (floral parts in 5 or multiple of 5).

Floral phyllotaxy Floral organs are borne on the thalamus either in spirals (acyclic or spiral, HJ., 0DJQROLD1\PSKDHD), whorls (cyclic, HJ., 3HWXQLD) or with some organs in spirals and other organs in whorls (spirocyclic or hemicyclic, HJ., 5DQXQFXOXV).

BRACTS Bract is a small leaf like structure present on the peduncle which bears a flower in its axil. The floral buds are usually protected by the bracts. Flower with a bract is described as bracteate and the flower without a bract is known as ebracteate. Types of bract

Scaly A membranous small bract present at the base of involucral bract, HJsunflower

Foliaceous Leaf like, expanded green bract HJ$GKDWRGD *URVVDQGUD

Petaloid Petals-like large, coloured bractsHJ %RXJDLQYLOOHD(XSKRUELD

Spathy A large modified bract which encloses spadix inflorescence totally or partially HJ $ORFDVLD0XVDetc

Epicalyx One or more whorls of bracteoles are found at the base of calyx, HJchina rose, strawberry.

Involucre A large number of bracts form compact one or more whorls around a flower or an inflorescence, HJ., sunflower.

Glumes The bracts found on the rachilla of spikelets. They may be sterile glumes or fertile glumes (lemma), HJ2U\]DVDWLYD.

Calyx and corolla together constitute accessory floral whorls. Depending upon the presence or absence of these whorls flower can be (i) Achlamydeous : Accessory floral whorls are absent HJ3LSHU (ii) Monochlamydeous : Only one accessory whorl (either calyx or corolla) or perianth (a collective term given to a group of undifferentiated calyx and corolla), is present HJ3RO\JRQXP (Polygonaceae), onion (Liliaceae). (iii) Dichlamydeous : Both the accessory whorls are present HJ +LELVFXVURVDVLQHQVLV MT BIOLOGY

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CALYX Calyx is the outermost whorl made up of sepals. It may be polysepalous (with free sepals) or gamosepalous (with fused sepals). On the basis of duration

Caducous Sepals fall off just after opening the bud, HJ $UJHPRQH3DSDYHUetc.

Deciduous Sepals fall off along with petals just after fertilisation, HJ mustard.

Persistent Sepals remain attached with the ripe fruit, HJ3LVXP2FLPXP, Family Solanaceae.

Pappus Spinous Hooded

Sepals modified into hairy structure which helps in dispersal of fruits, HJ sunflower.

In $FRQLWXP, one of the sepals is modified into a hood which covers the whole flower.

Leafy and petalloid In 0XVVDHQGD, one of the sepals is modified into a large leaf-like coloured structue.

Modification of sepals

In /DUNVSXU, from the base of one of the sepals arises a tubular outgrowth called spur.

In 7UDSD, the calyx is persistent and modified into two spines.

Spurred

Spinous

COROLLA Corolla is the second whorl of a flower made up of petals. It may be polypetalous (petals free) or gamopetalous (petals fused). Campanulate Corolla is bell-shaped, HJ3K\VDOLV

Caryophyllaceous Corolla consists of five petals with distinct limbs and claws. The claw and the limb of each petal remain more or less at right angle to each other, HJ'LDQWKXV

Rosaceous Five or more sessile or shortly clawed petals are bent horizontally like a saucer, HJ5RVDLQGLFD(rose).

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Types of polypetalous corolla

Cruciform Four free clawed petals are arranged diagonally or in the form of a cross, HJ mustard, candytuft, etc.

Papilionaceous Five unequal or irregular petals are arranged like a butterfly. The posterior large bilobed petal called standard or vexillum, overlaps the two smaller lateral petals named wings or alae. The latter overlap the two anterior petals, which are fused laterally by the upper anterior margins to form a boat shaped structure called keel or carina. It is the characteristic of sub-family Papilionaceae, HJ pea, bean etc.

Infundibuliform

SpinousTubular

Corolla is funnelshaped, HJ'DWXUD

Corolla is tubular or cylindrical, HJ central florets of sunflower

Rotate or wheel shaped Tube of the corolla is narrow and short and the limbs are at right angles to the tube,HJ., brinjal

Ligulate orSpinous strap-shaped The upper part of corolla is flattened like a strap with the lower part forming a short-tube, HJ, outer florets of sunflower Spinous Personate or masked

Types of gamopetalous corolla

Salver shaped or hypocrateriform Tubular corolla with spreading lobes, HJ, &OHURGHQGURQ

Corolla is bilabiate but the lips are so near to each other as to close the mouth of the corolla, HJ$QWLUUKLQXP

Corolla is like bell or inverted cup, HJ&DPSDQXOD

Corolla is divided into two lips-the upper lip and lower lip with the mouth gaping wide open, HJ., 2FLPXP

Campanulate

Bilabiate

AESTIVATION The mode of arrangement of sepals or petals with respect to one another in the floral bud is termed as aestivation.

Imbricate Aestivation of five parts, where one is exterior, one is interior and rest three are having one margin exterior and other interior.

Quincuncial Aestivation of 5 parts, where two are exterior, two interior and the fifth is having one margin exterior and the other interior.

Valvate Margins of adjacent sepals or petals or tepals just touch each other without any overlapping, HJ%UDVVLFD

Types of aestivation Descending imbricate or vexillary The standard petal is large and overlaps the two wing petals which in turn overlap the keel petals HJ sub-family Papilionaceae.

Twisted or contorted One margin of each petal overlaps the margin of an adjacent petal and the other margin being overlapped by margin of another adjacent petal, HJ +LELVFXVURVDVLQHQVLV

To know about Seven kingdom classification go to page no. 83

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Androecium Androecium is the third male whorl made up of stamens or microsporophylls. Each Inserted Stamens are shorter stamen consists of filament, anther and connective. Stamen than the flower Stamens may be borne directly on the thalamus or fused with petals (= epipetalous, can be H.J., 6RODQXP, 3HWXQLD) or tepals (= epiphyllous or epitepalous, H.J., $VSKRGHOXV). Exserted In majority of angiosperms, anthers are two lobed or dithecous. Each anther lobe Stamens protrude consists of two pollen sacs (or microsporangia). Thus a typical dithecous anther is out of the flower always tetralocular (or tetrasporangiate). In members of Family Malvaceae, anthers are monothecous. Pollen grains (or microspores) are produced in the microsporangium. Fusion of stamens with a dissimilar organ is called adhesion while fusion with a similar organ is known as cohesion. Types of cohesion between stamens Adelphous Stamens are fused by their filaments only; anthers are free. Fusion of filaments may produce a single group (monadelphous HJ+LELVFXV), two groups (diadelphous HJPea), or many groups (polyadelphous HJ&LWUXV).

Synandrous Stamens are fused by both their filaments as well as anthers HJ &XFXUELWD.

Syngenesious Stamens are fused by anthers only; filaments are free. HJ +HOLDQWKXV DQQXXV Syngenesious

The free stamens are called polyandrous. They may be equal or unequal in length. The two common types of unequal stamens are tetradynamous (four long and two short, H.J., %UDVVLFD) and didynamous (two long and two short, H.J., 2FLPXP).

Depending upon the position of stamens Diplostemonous Stamens of outer whorl alternate with petals (alternipetalous) and stamens of inner whorl lie opposite to the petals (antipetalous). HJ 0XUUD\DH[RWLFD&DVVLD.

Obdiplostemonous Here, stamens of outer whorl lie opposite to the petals (antipetalous) whereas those of inner whorl alternate with petals (alternipetalous). HJ 'LDQWKXV, 6WHOODULD

Fixation of anthers The mode of attachment of the anther to the filament varies greatly in flowers. Types of fixation of anthers Dorsifixed The filament is fixed to the dorsal side or back of the anther and anther is immovable, H.J., +LELVFXV URVD VLQHQVLV, 3DVVLIORUD, 6HVEDQLD, etc.

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Versatile The filament is attached to the middle of the connective so that anther lobes can swing on it freely H.J., grasses.

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Basifixed The filament is attached to the base of the anther, as in mustard, 'DWXUD, radish.

Adnate The filament is fixed to the anther in such a manner that it runs up the entire length of the anther at its backside, H.J., 0DJQROLD 5DQXQFXOXV 1\PSKDHD.

Types of connective Connective can be of following types: (i) Discrete : The connective is very narrow, so that the two anther lobes lie in close proximity as in $GKDWRGD, (XSKRUELD sp. (ii) Divaricate : The connective is broad and the two anther lobes are separated as in 7LOLD sp. (iii) Distractile : In 6DOYLD, the connective is highly elongated. Its one end bears a fertile anther lobe while the other end has a sterile anther lobe. (iv) Appendiculate : The connective becomes feathery and grows beyond the anther.

DEHISCENCE OF ANTHERS Longitudinal Slits appear lengthwise HJ'DWXUDmustard 5DQXQFXOXV&LWUXV

Types of Dehiscence of Anthers

Transverse Slits appear breadthwise HJ 0DOYD$OWKDHD

Laterorse Slits appear on the sides.

Introrse Slits are formed towards the inner side or centre of the flower.

Valvular Wall of anther lobes breaks at places and gets lifted like valves H.J., barberry, camphor.

Irregular Anther wall breaks irregularly H.J., 1DMDV

Cohesion of carpels

GYNOECIUM

Porous Dehiscence is by pores, which appear at the tips (6RODQXP tomato) or at base (&DVVLD).

Extrorse Slits lie towards the outer side of petals.

Apocarpous It is the fourth whorl made up of one or more carpels (megasporophylls). Gynoecium comprises of free Depending on the number of carpels, gynoecium may be monocarpellary, carpels, H.J., 5DQXQFXOXV. bicarpellary, tricarpellary, tetracarpellary and pentacarpellary and multicarpellary having one, two, three, four, five and many carpels respectively. Syncarpous Ovary has one or more chambers or loculi (singular loculus) : unilocular Gynoecium comprises of two or (H.J., pea); bilocular (H.J., mustard); trilocular (H.J., $VSDUDJXV); tetralocular more carpels which are fused, (H.J., 2FLPXP); pentalocular (H.J., China rose); multilocular (H.J., $OWKDHD, lady’s H.J., +LELVFXV. finger). In the chambers there are present oval outgrowths called ovules. Ovules later mature into seeds while the wall of the ovary forms a covering called pericarp. The two together constitute a fruit. A sterile and undeveloped pistil is called pistillode. Types of style Terminal Style lying in the same straight line with the ovary, HJ+LELVFXV

Lateral Style arising from the side of the ovary, H.J., 3RWHQWLOOD

Gynobasic Style arising from the depression in the centre of the ovary or directly from thalamus, H.J., 2FLPXP

Stylopodium : When base of the style is swollen to form a pad like structure, it is called stylopodium, H.J., Family Apiaceae (Umbelliferae). Plumose stigma : Feather like stigma is called plumose stigma, H.J., grasses. Resupination : Turning or twisting of ovary or flower through 180°, L.H., upside down is called resupination. HJ, most orchids.

PLACENTATION Placenta is a parenchymatous cushion present inside the ovary where ovules are borne. An ovary may have one or more placentae. The number, position and arrangement or distribution of placentae inside an ovary is called placentation. MT BIOLOGY

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Parietal Occurs in a bi-or multicarpellary syncarpous ovary. There are two or more longitudinal placentae attached to the ovary wall. Ovary can be unilocular or become falsely two or more locular due to ingrowth of placentae or formation of false septum, called replum. HJ members of Family Brassicaceae.

Marginal Occurs in a monocarpellary, unilocular ovary. The placenta develops and ovules are borne along the junction of the two margins of the carpel,HJmembers of Family Leguminosae.

Ovary wall

Superficial Locule Occurs in multicarpellary, multilocular ovary. The ovules are borne on placentae which develop all around the inner surface Septum Ovules of the partition wall, HJ1\PSKDHD

Types of placentation

Axile It occurs in polycarpellary syncarpous gynoecium. The ovary is many chambered. The walls of the carpels in the centre of the ovary are united to form an axis, which bears the placentae with ovules, HJ 3HWXQLD (bilocular), $VSKRGHOXV (trilocular), tomato (bi or tetralocular), +LELVFXV (pentalocular), $OWKDHD and lemon (multilocular).

Free central The pistil is polycarpellary and syncarpous but the ovary is unilocular. The ovules are borne around a central column which is not connected with the ovary wall by any septum, HJ 'LDQWKXV 6LOHQH3ULPXOD, etc.

Basal The pistil can be monocarpellary or syncarpous. The ovary is unilocular. It bears a single placenta at the base with generally a single ovule, HJ5DQXQFXOXV, sunflower, marigold.

THALAMUS The thalamus is the swollen part of the flower which lies at the tip of the pedicel and bears floral organs. In some plants, thalamus shows distinct nodes and internodes. The internode between calyx and corolla is termed as anthophore, H.J., 6LOHQH; that between corolla and androecium, is called androphore, H.J.,3DVVLIORUD and that between androecium and gynoecium, is called gynophore or gynandrophore, H.J., &OHRPH. Sometimes thalamus is prolonged into gynoecium to form a central axis, it is called carpophore, H.J., coriander.

1.

2. 3. 4.

5.

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Table: Differences between Hypogynous, Perigynous and Epigynous flowers Hypogynous Flowers Perigynous Flowers Epigynous Flowers The upper part of thalamus is slightly The upper part of thalamus may be disc The upper part of thalamus is usually flaskswollen and forms a cushion like shaped, cup-shaped or flask-shaped. shaped or tubular. disc. Calyx, corolla and androecium arise Calyx, corolla and androecium arise from Calyx, corolla and androecium arise from below the level of ovary. around the ovary and not beneath it. above the level of ovary. Ovary is superior while all other floral Ovary is half-superior/half-inferior. Ovary is inferior while all other floral parts parts are inferior. are superior. The gynoecium is placed at the top The ovary is placed at the bottom of cup The ovary is completely inserted and the of the thalamus. The wall of ovary is or flask-shaped thalamus. Ovary wall is wall of ovary is fused with the thalamus. not fused with the thalamus. not fused with the thalamus. Calyx, corolla and androecium remain Calyx, corolla and androecium often Calyx, corolla and androecium develop separated from the gynoecium so that develop from a common base. The ovary jointly from the neck of hollowed out of gynoecium may or may not be visible thalamus so that the ovary is not visible the ovary is visible from outside. from outside. from outside.

MT BIOLOGY

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New MCQs 1. Inflorescence is compact unisexual and often hanging in (a) $FK\UDQWKHV (b) 6DOL[ (c) ,EHULV (d) /LQDULD 2. The arrangement of the floral organs around the axis of a flower is known as (a) isomery (b) floral phyllotaxy (c) floral symmetry (d) floral morphology. 3. Which of the following shows urceolate corolla? (a) %U\RSK\OOXP (b) 6RODQXPQLJUXP (c) 3HWXQLD (d) &OHURGHQGURQ 4. Polypetalous corolla is found in all of the following except (a) mustard (b) carnation (c) rose (d) sunflower. 5. In which of the following plants polycarpellary apocarpous ovary is found? (a) Rose (b) Lotus (c) 5DQXQFXOXV (d) All of these 6. Axile placentation is found in (b) /DUNVSXU (a) &DSSDULV (d) 9LROD (c) $OWKDHD 7. Gynobasic style is found in (a) 6DOYLD (b) 2FLPXP (d) both (a) and (b). (c) 3HWXQLD 8. Carpophore is found in (a) coriander (c) rose

(b) mustard (d) none of these.

9. Floral diagram fails to indicate (a) epiphylly and epipetaly (b) aestivation and placentation (c) position of ovary on the thalamus (d) cohesion of carpels.

5. A scorpioid cyme having all the flowers in the same plane is (a) rhipidium (b) bostryx (c) cincinnus (d) drepanium. (AMU 2014) 6. When the margin of the thalamus grows upward enclosing ovary completely and getting fused with it while the other parts of flower arise above the ovary, the ovary is said to be (a) inferior (b) superior (c) half inferior (d) half superior. (AMU 2013) 7. )LFXV inflorescence is an example of which kind of inflorescence? (a) Raceme (b) Spike (c) Cyathium (d) Hypanthodium (e) Catkin (CMC Vellore 2013) 8. Vexillum is found in Family (a) Papillionaceae (b) Rosaceae (c) Caryophyllaceae (d) Cruciferae. (Odisha 2012) 9. When placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, the placentation is termed as (a) axile (b) parietal (c) marginal (d) basal. (AMU 2012) 10. The inflorescence found in grasses and sedges is (a) compound spike (b) spikelet (Odisha 2012) (c) catkin (d) spadix.

Assertion & Reason

10. The flowers in a cyathium resemble the ray florets of sunflower in being (a) sessile (b) imperfect (c) neuter (d) bisexual.

Exam Section 1. Axile placentation is present in (a) pea (b) $UJHPRQH (c) 'LDQWKXV (d) lemon.

3. Cruciform corolla is characteristic of Family (a) Asteraceae (b) Brassicaceae (c) Euphorbiaceae (d) Caryophyllaceae. (UPCPMT 2015) 4. The inflorescence in which sessile flowers are borne acropetally on an elongated rachis is called (a) raceme (b) spike (c) catkin (d) corymb. (AMU 2014)

(AIPMT 2015)

2. Syngenesious stamens are found in (b) &XFXUELWD (a) +HOLDQWKXV (c) +LELVFXV (d) &DORWURSLV.

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 (A) : Syngenesious condition is a type of cohesion of stamens.

(UPCPMT 2015)

Reason (R) : In syngenesious cohesion, the stamens remain fused in the region of anthers only. MT BIOLOGY

TODAY | MAY ‘16

19

2. Assertion (A) : Capitulum inflorescence is typical of Family Compositae. Reason (R) : A capitulum bears two types of sessile flowers called florets. 3. Assertion (A) : Sterile stamens are called staminodes. Reason (R) : Staminodes are under-developed male reproductive parts which lack functional pollen grains. 4. Assertion (A) : Spadix is a special type of spike which possesses a fleshy peduncle and large bract called spathe. Reason (R) : Spadix is found in mulberry and candytuft. 5. Assertion (A) : Cruciform polypetalous corolla is found in the members of Family Asclepiadaceae. Reason (R) : In cruciform corolla five unguiculate or clawed petals with limbs are horizontally bent.

Short Answer Type Questions 1. Fill in the blanks: (a) The posterior large bilobed petal called ______ of a papilionaceous corolla overlaps the two smaller, lateral petals named ______. (b) When stamens alternate with petals they are called ______ whereas stamens opposite to petals are termed as ______. (c) In cymose head, sessile or subsessile flowers are borne _______around a receptacle. (d) The phenomenon of having same basic number of parts in different floral organs is known as _______. (e) _______ is the arrangement of accessory floral organs in relation to one another in the floral bud. 2. Classify anthers on the basis of their mode of attachment to the filaments. 3. How can you differentiate between accrescent and marcescent calyx? 4. Briefly describe hypanthodium. Give examples of plants where it is found.

ANSWER KEY 1. 6.

New MCQs (b) 2. (c) (c) 7. (d)

3. 8.

(a) (a)

4. 9.

(d) (c)

5. (d) 10. (b)

2. (a) 3. (b) 7. (d) 8. (a) Assertion & Reason

4. 9.

(b) (c)

5. (a) 10. (b)

4.

(c)

5.

Exam Section 1. 6.

(d) (a)

1.

(b)

2.

(b)

3.

(a)

(d)

Short Answer Type Questions 1. (a) vexillum, alae (c) centrifugally (e) Aestivation 20

MT BIOLOGY

(b) alternipetalous, antipetalous (d) isomery

TODAY | MAY ‘16

2. The anthers may be attached to the filaments by any of the following four methods: (i) Basifixed or Innate : The anther is fixed directly at the top of the filament so that the latter joins the anther at its base, HJ, mustard, radish. (ii) Adnate : The filament runs throughout the length of the anther or becomes continuous with the connective HJ 5DQXQFXOXV0DJQROLD1\PSKDHD. (iii) Dorsifixed : The filament is firmly fixed to the back of the anther, HJ3DVVLIORUD6HVEDQLD3UXQXV. (iv) Versatile : The filament is attached generally to the back of the anther and the anther can swing freely, HJ, grasses. 3. Both of these are persistent calyx. But the basic difference between the two is that accrescent is the persistent calyx growing along with the fruit such as in 3K\VDOLV while marcescent is the dried up form of persistent calyx before being shed such as in guava. 4. Hypanthodium has a flask-shaped fleshy receptacle which possesses a narrow canal and a terminal pore at one end. The pore is surrounded by a few scales while the canal is lined by downwardly pointed hairs. Internally the receptacle bears male flowers towards the pore and female flowers towards the base. Sterile, neuter or gall flowers occur in between the two groups. The inflorescence is formed by the condensation of three types of flower-bearing axes (cymose groups). Hypanthodium is found in the genus )LFXVof the Family Moraceae, HJ, peepal ()LFXVUHOLJLRVD) banyan ()LFXV EHQJKDOHQVLV), fig ()LFXVFDULFD). 

on : m a Ex th May 29

 1.

2.

3.

4.

5.

The protists have (a) only free nucleic acid aggregates (b) membrane bound nucleoproteins lying embedded in the cytoplasm (c) gene containing nucleoproteins condensed together in loose mass (d) nucleoprotein in direct contact with the rest of the cell substance. Identification and classification of plants on the basis of only morphological characters constitute (a) biosystematics (b) α-taxonomy (c) β-taxonomy (d) new systematics. A common characteristic of all vertebrates without exception is (a) the presence of well-developed skull (b) the division of body into head, neck, trunk and tail (c) their body covered with an exoskeleton (d) the possession of two pairs of functional appendages. In oxidative phosphorylation, the steps are as follows : CoQ → Cyt F → Cyt DD3 → O2 (a) CoQ → Cyt F is H+ absorbing site (b) Cyt DD3 → O2 is H+ yielding site (c) CoQ → Cyt F is H+ yielding site and Cyt DD3 → O2 is H+ absorbing site (d) no H+ is absorbed or released. Which DNA molecule among the following will melt at lowest temperature ? (a) 5′-A-A-T-G-C-T-G-C-3′ 3′-T-T-A-C-G-A-C-G-5′ (b) 5′-A-A-T-A-A-A-G-C-T-3′ 3′-T-T-A-T-T-T-C-G-A-5′ (c) 5′-G-C-A-T-A-G-C-T-3′ 3′-C-G-T-A-T-C-G-A-5′ (d) 5′-A-T-G-C-T-G-A-T-3′ 3′-T-A-C-G-A-C-T-A-5′

6.

Elongated structure on upper cortex of lichen, having same algal and fungal partners as in main thallus is (a) soredium (b) isidium (c) cephalodium (d) cyphellae. 7. Labyrinthitis is (a) a ringing sensation in the ears (b) inflammation of the middle ear (c) inflammation of eustachian tube (d) inflammation of the inner ear. 8. Stanley L. Miller performed the first successful experiment to assess the validity of the claim for origin of organic molecules in the primeval earth condition. The control apparatus contained every arrangement except that it was deviod of (a) ammonia (b) methane (c) oxygen (d) energy source. 9. Cleavage differs from mitosis in (a) separating of chromosomes partially (b) slow DNA replication (c) having no growth phase between successive divisions (d) having impartial cellular divisions. 10. An ecosystem which can be easily damaged but can recover after some time if damaging effect stops will be having (a) low stability and high resilience (b) high stability and low resilience (c) low stability and low resilience (d) high stability and high resilience. 11. Four sepals K 4 or (2 + 2) is the characteristic feature of the Family (a) Solanaceae (b) Papilionaceae (c) Malvaceae (d) Brassicaceae. 12. In plant mineral nutrition, elements are classified as macro or micro-elements depending upon their (a) relative presence in plant ash (b) relative importance in plant growth (c) relative amount required in plants (d) relative availability in soil. MT BIOLOGY

TODAY | MAY ‘16

21

13. In which one of the following sets of three items each belong to the category mentioned against them? (a) Lysine, glycine, thymine –– Amino acids (b) Myosin, oxytocin and gastrin –– Hormones (c) Rennin, helicase and hyaluronidase –– Enzymes (d) Optic nerve, oculomotor, vagus –– Sensory nerves 14. Which one of the following statements regarding enzyme inhibition is correct? (a) Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein. (b) Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme. (c) Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate. (d) Competitive inhibition is usually irreversible since the addition of more substrate tends to reduce the effect of the inhibitor. 15. Greenhouse gases are (a) absorbers of long-wave heat radiations from earth (b) transparent to both solar radiations and long-wave radiations from earth (c) absorbers of solar radiations for warming the atmosphere of earth (d) transparent to emissions from earth for passage into outer space. 16. Immunogens are (a) substances which are incapable of inducing antibody formation themselves, but can induce antibodies on combining with larger molecules (b) large phagocytic cells that rise by enlargement of monocytes (c) molecules that react with antibodies (d) molecules that induce an immune response by organisms immune system. 17. Complete failure of the anterior lobe of pituitary gland causes (a) Addison’s disease (b) acromegaly (c) Cushing’s disease (d) Simmonds’ disease. 18. Megasporophylls which are arranged spirally and acropetally on the central axis of the female cone of Pinus bear (a) 4 megasporangia on dorsal surface (b) 2 megasporangia on ventral surface (c) 2 megasporangia on dorsal surface (d) 4 megasporangia on ventral surface. 19. Laurer’s canal is present in (a) Fasciola (b) Taenia (c) Ascaris (d) cockroach. 20. Photosynthesis cannot continue for long if during light reaction, only cyclic photophosphorylation takes place. This is because (a) only ATP is formed, NADPH+ + H+ is not formed (b) photosystem I stops getting exicted at a wavelength of light beyond 680 nm. 22

MT BIOLOGY

TODAY | MAY ‘16

21.

22.

23.

24.

25.

26.

27.

28.

(c) there is unidirectional cyclic movement of the electrons (d) there is no evolution of O2. During which stages (or prophase-I substages) of meiosis do you expect to find the bivalents and DNA replication respectively? (a) Pachytene and interphase (between two meiotic divisions) (b) Leptotene and interphase (between two meiotic divisions) (c) Pachytene and S phase (of interphase just prior to prophase I) (d) Leptotene and S-phase (of interphase prior to prophase I). What is the work of progesterone which is present in oral contraceptive pills ? (a) To inhibit ovulation (b) To check oogenesis (c) To check entry of sperms into cervix and to make them inactive (d) To check sexual behaviour Acromion process is characteristically found in the (a) pectoral girdle of mammals (b) sperm of mammals (c) pelvic girdle of mammals (d) skull of mammals. Demographic transition is conversion of (a) high growing population to slow growing population (b) slow growing population to high growing population (c) growing population to zero growing population (d) transition from few resources to multiresource society. What happens when the pacemaker becomes nonfunctional? (a) Only auricles contract rhythmically (b) Only ventricles contract rhythmically (c) Cardiac muscles do not undergo co-ordinated rhythmic movements (d) Auricles and ventricles contract rhythmically Loading of phloem is related to (a) increase of sugar in phloem (b) elongation of phloem cell (c) separation of phloem parenchyma (d) strengthening of phloem fibre. Food web is constituted by (a) various interlinked food chains in a community (b) relationship between animals and plants (c) relationship between organisms and their environment (d) relationship between animals, plants and microbes. Which of the following is the correct sequence of layers in typical monocot root (from outer surface to inside)? (a) Pericycle, cortex, endodermis, epiblema (b) Epiblema, endodermis, cortex, pericycle (c) Epiblema, cortex, endodermis, pericycle (d) Epiblema, pericycle, cortex, endodermis.

29. 6\FRQ belongs to a group of animals, which are best described as (a) unicellular or acellular (b) multicellular without any tissue organisation (c) multicellular with a gastrovascular system (d) multicellular having tissue organisation, but no body cavity. 30. The change in the partial pressure of CO 2 in blood is determined by (a) carotid sinus (b) carotid bodies (c) surface of lungs (d) carotid sinus and carotid bodies. 31. Compound tissue is defined as (a) similar types of cells held together by connective tissue (b) different types of cells which are different in structure and function (c) different types of cells performing one function (d) similar cells at different regions performing different functions. 32. The slow twitch muscle fibres which are rich in myoglobin and have abundant mitochondria are (a) white skeletal muscles (b) cardiac muscles (c) red skeletal muscles (d) involuntary muscles. 33. Vegetative fertilisation leading to the formation of endosperm refers to (a) fusion of male gamete with diploid secondary nucleus (b) fusion of female gamete with diploid secondary nucleus (c) fusion of two diploid vegetative cells (d) fusion of two male gametes. 34. Ribosomes are particles about 200 Å units in diameter consisting of protein and RNA. The percentage of protein and RNA is respectively (a) 80% and 20% (b) 70% and 30% (c) 50% and 50% (d) 40% and 60%. 35. Which one of the following is not observed in biodiversity hotspots? (a) Lesser inter-specific competition (b) Species richness (c) Endemism (d) Accelerated species loss 36. Restriction enzymes present in several microorganism cut foreign DNA at specific sites and destroy them. The enzymes do not destroy the cellular DNA because (a) the cellular DNA does not have the specific sites (b) the susceptible specific sites are masked by proteins (c) the restriction enzyme susceptible sites are modified by cellular enzymes (d) the restriction enzymes and DNA occupy different compartments.

37. A human female is born with a million of eggs (primary oocyte) at the time of birth, only some 500 eggs get a chance of maturity. What is the destiny of rest of the eggs? (a) They differentiate back to thecal and granulosa cells. (b) They nurture the dominant follicular cell. (c) They move out of the ovary and are destroyed by leucocytes. (d) They break down and are absorbed LH. degenerative follicular atresia. 38. Which of the following statements is correct regarding evolution of mankind? (a) Homo erectus is preceded by Homo habilis. (b) Neanderthal man and Cro-Magnon man were living at the same time. (c) Australopithecus used to live in Australia. (d) None of the above. 39. Rotenones are natural insecticides which are obtained from the (a) roots of Derris elliptica (b) inflorescence of Chrysanthemum cinerariifolium (c) stem of Lonchocarpus nicou (d) leaves of Urginea maritima 40. hCG is secreted from the (a) syncytiotrophoblast (b) cytotrophoblast (c) embryoblast (d) all of these. Direction (41-60): In the following questions, a statement of Assertion is followed by a statement of Reason. Mark the correct choice as : (a) If both assertion and reason are true and reason is the correct explanation of assertion. (b) If both assertion and reason are true but reason is not the correct explanation of assertion. (c) If assertion is true but reason is false. (d) If both assertion and reason are false. 41. Assertion : Lipids present in the outer and inner side of the bilayer membrane are mostly same. Reason : Oligosaccharides are attached to external surface as well as inner surface of a biomembrane. 42. Assertion : Materials are exchanged between epithelial and connective tissues by diffusion. Reason : Blood vessels are usually absent in epithelial tissues. 43. Assertion : Diffusion accounts for complete absorption of nutrients from the intestine. Reason : Diffusion is a very fast process of absorption. 44. Assertion : During exchange of gases, carbon dioxide passes from the blood to the alveoli. Reason : The partial pressure of carbon dioxide is higher in deoxygenated blood than in alveoli. MT BIOLOGY

TODAY | MAY ‘16

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45. Assertion : A concentric vascular bundle may be amphicribal or amphivasal. Reason : Xylem is water conducting tissue while phloem transport food products from source to the sink. 46. Assertion : Girdling is removal of xylem tissues from a stem or branch. Reason : Girdling give the evidence for translocation of sugar through xylem tissue. 47. Assertion : If human urine is allowed to stand for some time, it smells strongly of ammonia. Reason : The main constituent of human urine is ammonia. 48. Assertion : The maximum number of trophic levels is hardly 3-5 in terrestrial ecosystems and 4-6 in aquatic ecosystems. Reason : The energy flow always occur in one direction through successive trophic levels, in a food chain. 49. Assertion : 2, 4 - D and 2, 4, 5 - T are used as weedicide. Reason : 2, 4 - D and 2, 4,5 - T are synthetic auxins which move in all directions inside a plant. 50. Assertion : Monoclonal antibodies are used to recognise several bacterial pathogens, diagnose pregnancy, treat allergies and treat cancer. Reason : Monoclonal antibodies is a specific antibody produced by unidentical cells derived from a single parent. 51. Assertion : Secretory phase is caused by increased production of progesterone. Reason : Progesterone hormone is required for the maintenance of pregnancy. 52. Assertion : Chloragogen cells are analogous to liver cells of vertebrates. Reason : Chloragogen cells help in excretion and food storage. 53. Assertion : Transformation involves the donor and recipient bacteria. Reason : Transformation is used to produce recombinant DNA. 54. Assertion : Closed circulatory system is more efficient than open circulatory system. Reason : The open circulatory system considerably enhances the speed, precision and efficiency of circulation. 55. Assertion : Corpus callosum is present in the space between arachnoid membrane and pia mater. Reason : Corpus callosum serves to maintain a constant pressure inside the cranium. 56. Assertion : The desirable character and desired sex of superior variety are kept constant for many generations by micropropagation. Reason : Micropropagation form genetically similar plants. 24

MT BIOLOGY

TODAY | MAY ‘16

57. Assertion : Life cycle of Fasciola hepatica is digenetic. Reason : Life cycle of Fasciola hepatica is completed in two hosts, primary host is snail while intermediate host is sheep. 58. Assertion : The product of the first reaction of the Krebs cycle is citric acid, a six-carbon compound. Reason : The first reaction of the Krebs cycle is the condensation of acetyl CoA with oxaloacetate. 59. Assertion : A sanctuary is protected area meant for the conservation of animals only. Reason : Sanctuaries are tracts of land where fauna can take refuge without being hunted. 60. Assertion : Spermiogenesis is the process of the transformation of spermatids into spermatozoa. Reason : Spermiogenesis involves multiplication phase, growth phase, maturation phase and differentiation phase.

ANSWER KEY 1. 7. 13. 19. 25. 31. 37. 43. 49. 55.

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

2. 8. 14. 20. 26. 32. 38. 44. 50. 56.

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

3. 9. 15. 21. 27. 33. 39. 45. 51. 57.

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

4. 10. 16. 22. 28. 34. 40. 46. 52. 58.

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

5. 11. 17. 23. 29. 35. 41. 47. 53. 59.

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

6. 12. 18. 24. 30. 36. 42. 48. 54. 60.

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

MARCH 2016 1. BIOINFORMATICS

2. RETROVIRUS

3. PROMOTER

4. INFUNDIBULUM

5. AUTOGAMY

6. ANGINA

7. HYDROPONICS

8. ENDARCH

9. OPSIN

10.TENDRIL

Winners : Anuradha Chandra (West Bengal), Taniya Mondal (West Bengal), Jagadish Rana (Odisha), Jupita Hazarika (Guwahati), Thommen Shaji (Kerala)

ANSWERS

WHO AM I ...

1.

Periodontal ligament

Pg. 65

2.

Microinjection

Pg. 74

Class XI

Digestion and Absorption

1 1 – 1 J&K

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Kerala

K.CET

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AIIMS

AMU

2014

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2013

1

The lips are covered with skin on the outer side and lined with mucous membrane on the inner side. Mouth consists of two parts, vestibule and oral cavity. s Vestibule is a narrow space enclosed between the lips and cheeks externally and the gums and teeth internally. Its lining contains mucous glands. s The vestibule leads into the oral cavity. The oral or buccal cavity is a chamber in which food is chewed. It is lined by a stratified squamous epithelium, with keratin covering those areas which are subjected to significant abrasion, such as tongue and palate. s Tongue is a strong muscular organ that helps in chewing of food. It also aids in swallowing and is an organ of taste. Upper surface of tongue bears four types of papillae listed in the flow chart.

2012

Mouth s Mouth is a transverse slit which is bound by two soft, movable lips (upper and lower).

4

LH mouth (vestibule and oral or buccal cavity), pharynx, oesophagus, stomach, small intestine, large intestine and anus.

2011

s Adult alimentary canal is a long tube (8-10m long) which consists of several organs

AIPMT/NEET

ALIMENTARY CANAL

Analysis of various PMTs from 2011-2015

canal, accessory organs and tissues. The accessory organs are not part of the tract but secrete substances into it YLD connecting ducts. s Alimentary canal is a tube-like structure extending from the mouth to the anus whereas accessory organs include salivary glands, gall bladder, liver and exocrine pancreas. s The overall function of the digestive system is to process ingested foods into molecular forms that are then transferred to the body’s circulatory system which distributes them to all body cells. s The digestive system is under the local neural control of enteric nervous system and of the central nervous system.

2015

s The human digestive system includes the gastrointestinal tract (GI) or alimentary

25

s Palate refers to the roof of the oral cavity . It is further

divided into two parts : hard palate (anterior) and soft palate (posterior). Hinder free part of the soft palate hangs down freely as uvula. s Teeth are hard structures which are meant for

holding, cutting, grinding and crushing the food. In most mammals, teeth are diphyodont (two sets of teeth YL] milk or deciduous and permanent), thecodont (teeth are embedded in the sockets of the jaw bones) and heterodont (different types of teeth). Four kinds of teeth present in the humans are incisors (8) for cutting and biting, canines (4) for tearing and piercing, premolars (8) for crushing and grinding and molars (12) for crushing, grinding and masticating. 2123 ⎛ 2 1 2 3⎞ Dental formula of permanent teeth is ⎜ i = , c = , pm = , m = ⎟ while dental formula of milk teeth is 2123 ⎝ 2 1 2 1 2102 ⎛ 2 ⎞ ⎜ i = , c = , m = , premolars are absent in milk teeeth ⎟ . 2 1 2102 ⎝ 2 ⎠

3⎠

2

Structure of tooth

Crown

Enamel

Dentine

Hardest substance of human body which covers the dentine It has numerous fine canaliculi that pass radially from the pulp cavity towards the enamel.

Neck

Pulp cavity

Contains mass of cells, nerves and blood vessels

Gum gingiva

Continuous with the sockets surrounding the root

Root

Bone of alveolus

Root canal

Narrow extension of pulp cavity which runs through root of tooth

Cementum

It covers the root of the tooth.

Periodontal ligament

Made up of collagen fibres and covers the cement. It fixes the tooth in its socket.

Fig. : Structure of a tooth

s Mouth performs mastication which refers to the mechanical breakdown of food by chewing and chopping actions of the teeth.

Mastication breaks up the food into small particles, which provides a greater surface area for digestion and enables the food to pass through the oesophagus. Bolus and deglutition Bolus is a ball of chewed food bound together with saliva that is formed in the mouth by the action of tongue. The bolus is shaped to a size that allows it to pass into the oesophagus after swallowing LHdeglutition which is a reflex response to presence of food in pharynx. 26

MT BIOLOGY

TODAY | MAY ‘16

Pharynx air. It is divisible into nasopharynx (lies behind nasal cavities), oropharynx (serves as a common passage for food and air), laryngopharynx (leads into oesophagus). Lymphatic tissue of the pharynx and oral cavity are arranged in a ring like manner called Waldeyer’s ring. It consists of pharyngeal, tubal, palatine and lingual tonsils. These lymphoid tissues are active in production of immunoglobulin-A.

Oesophagus (Gullet) s Oesophagus or food pipe lies behind

Parotid gland Sublingual gland Submandibular gland

Mouth (oral cavity) Tongue

Salivary glands

s Pharynx is a common passage for food and

Pharynx

Oesophagus

Stomach Pancreas Spleen

Liver Gall bladder

Large intestine

Small intestine

trachea and comprises of cervical part (in Transverse colon the neck), thoracic part (in the thorax) and Duodenum abdominal part (in the abdomen). Descending colon Jejunum s It transfers food from pharynx to stomach. Ascending colon Ileum No digestion takes place in it. There is a thin Caecum Sigmoid colon epithelium, no villi, a few glands secreting Rectum mucus and a thick muscle layer, which Appendix propels the food by peristalsis. Anus Anal canal s Peristalsis is a wave of contraction and Fig.: Human digestive system relaxation of muscles that initiates in the oesophagus as soon as food enters into it through mouth. This wave then propagates down the oesophagus in an anterograde direction throughout the alimentary canal. Peristaltic movement comprises relaxation of circular smooth muscles, then their contraction behind the chewed material to keep it from moving backward, then longitudinal contraction to push it forward. This movement is completely involuntary.

Stomach (Gaster) s Stomach is a J-shaped expanded bag, located between the oesophagus and small intestine. It has two borders called the

greater and lesser curvatures and is divided into four main regions: cardia (the uppermost region into which oesophagus opens), fundus (region next to the cardia), body (main central region) and pylorus (last portion that connects to the duodenum). Both the cardiac and pyloric ends of the stomach are bound by sphincters (cardiac and pyloric respectively), which regulate the entry and exit of food in and out of the stomach.

Small intestine s It is the longest part of alimentary canal and is composed of duodenum, jejunum and ileum. It averages approximately 6 m

in length, extending from the pyloric sphincter of the stomach to the ileo-caecal valve. It is compressed into numerous folds and occupies a large proportion of the abdominal cavity. s The duodenum is the proximal C-shaped section that serves a mixing function as it combines digestive secretions from the pancreas and liver with the contents expelled from the stomach. The start of the jejunum is marked by a sharp bend, the duodenojejunal flexure. The final portion, the ileum, is the longest segment and empties into the caecum at the ileocaecal junction. s Along the entire length of the small intestine, small nodules of lymphatic tissue can be seen. These nodules get clustered together in groups at some places, particularly along the ileum and are called Peyer’s patches. These nodules produce lymphocytes. s Small finger-like projections of the mucosa called villi are present along the entire length of the small intestine (except Peyer’s patches). These villi increase the absorptive surface area of the small intestine. The villi mucosa of the small intestine is thrown into a series of permanent circular folds called Valves of Kerkring or plicae circulares. They further increase the surface area for absorption. MT BIOLOGY

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Large intestine s The large intestine is horse-shoe shaped and extends around the small intestine like a frame. It consists of the appendix,

caecum, colon (ascending, transverse, descending and sigmoid) and rectum. It has a length of approximately 1.5 m and a width of 7.5 cm. s The caecum is the expanded pouch that receives material from the ileum and starts to compress food products into faecal material. Food then travels along the colon. The wall of the colon is made up of several pouches (haustra) that are held under tension by three thick bands of muscle (taeniae coli). The rectum expands to hold faecal matter before it passes through the anorectal canal to the anus. Thick bands of muscle, known as sphincters, control the passage of faeces.

HISTOLOGY OF ALIMENTARY CANAL s Four basic layers of alimentary canal from inner lumen to outer surface are : mucosa, submucosa, muscularis externa and serosa. Mucosa

It is the innermost layer of the digestive tract that has specialised epithelial cells, supported by an underlying connective tissue layer called the lamina propria and muscularis mucosa.

Endocrine cells

Lumen of gastrointestinal tract

Epithelium

It forms glands that secrete enzymes and large quantities of mucus that helps in lubrication and also prevents digestion of gut wall by its own enzymes. Lamina propria

Mucous cells

It contains blood vessels, nerves, lymphoid tissue and glands.

Exocrine cells

Muscularis mucosa

Major blood and lymphatic vessels

This comprises layers of smooth muscle which can contract to change the shape of lumen. Submucosa

It consists of loose connective tissue, blood and lymphatic vessels and glands. The submucosal plexus or Meissner’s plexus controls secretion of intestinal juice. Circular muscles

Longitudinal muscles Abdominal cavity

Ducts from external exocrine glands (liver, pancreas, salivary glands)

From the autonomic nervous system

Muscularis externa

This smooth muscle layer has inner circular and outer longitudinal layer of muscle fibres separated by the myenteric plexus or Auerbach’s plexus. Auerbach’s plexus controls peristalsis. Serosa

This is the outermost layer which is formed by squamous epithelium and areolar connective tissue. It is continuous with mesentery.

Fig. : Structure of the gastrointestinal wall in longitudinal section

DIGESTIVE GLANDS s The human digestive glands include salivary glands, gastric glands, liver, pancreas and intestinal glands.

Salivary glands s Large quantities of saliva (average volume secreted per day is 1.5 litre) is produced by the three pairs of salivary glands. Saliva is slightly

acidic (pH 6.8) and it contains water, mucin (forms mucus when dissolved in water), enzymes (salivary amylase and lysozyme) and ions. Water and mucin lubricate the food and bind the food particles together to form a bolus. Salivary amylase acts on α, 1 → 4 linkages of the starch molecule to break it into disaccharide (maltose). s Water in saliva dissolves food that stimulates the taste buds and initiates the digestive reactions. Water and mucus also facilitate speech by lubricating the oral cavity and tongue. Lysozyme destroys bacteria. Bicarbonate and phosphate ions buffer the acidic foods. Sodium and chloride ions activate the enzyme, α-amylase. 28

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Parotid duct or Stenson’s duct Carries the secretion of parotid gland and opens opposite to the second molar tooth in mouth Parotid gland Largest salivary gland, contributes 25% of total salivary secretion, located in front of ears Sublingual gland Smallest salivary gland, contributes 5% of total salivary secretion, sub-adjacent to mucosa of floor of mouth. Its secretion is discharged by 5-15 small ducts (ducts of Rivinus) into the sublingual part of mouth Submandibular duct or Wharton’s duct Carries secretion of submandibular gland and opens into the floor of mouth near the lower central incisors

Submandibular gland Contributes 70% of total salivary secretion and is medial to the mandible in submaxillary triangle

Fig.: Location of different salivary glands

Gastric glands s There are four different types of cells in the gastric pits functioning as gastric glands and secreting different components of

the gastric juices. They are mucous (goblet) cells, chief cells, parietal cells and G cells (enteroendocrine cells).

Gastric lumen Simple columnar epithelium

Gastric pit

Gastric gland

Mucous (Goblet) cells These are mucus secreting cells. The mucus secreted by these glands serves to lubricate the food canal besides protecting the lining of the stomach from being corroded by the acid and the protease (pepsin) present in the gastric juice. Parietal cell Parietal (oxyntic) cells secrete H+ and Cl– ions (HCl) into the lumen of the stomach and another molecule called the intrinsic factor, which is responsible for the absorption of vitamin B12 (cyanocobalamine also known as the extrinsic factor) and necessary for the formation of red blood cells. HCl kills microbes coming in with the food. It converts the enzyme pepsinogen into its active form pepsin and provides acidic pH for its activity. It also stimulates the secretion of hormones from the enteroendocrine glands, which in turn stimulate the release of bile and pancreatic juice.

Chief cell Chief (peptic or zymogenic) cells secrete the inactive enzymes pepsinogen and prorennin. Gastric lipase and gastric amylase are secreted in insignificant amounts by the chief cells.

Enteroendocrine cell Enteroendocrine cells, which are located at the base of the gastric pits (also called G cells), are responsible for the secretion of hormone gastrin. Gastrin stimulates the secretion of gastric juice and increases gastric mobility. Fig. : Location and function of gastric glands MT BIOLOGY

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Liver s It is the largest internal gland of the body which is reddish brown in colour. It lies in the upper right side of the abdominal cavity

just below the diaphragm. It is heavier in males than females. In males it generally weighs 1.4-1.8 kg and in females 1.2-1.4 kg. The liver is covered by two sheaths–an outer membranous serous capsule consisting of visceral peritoneum and an inner Glisson’s capsule of a thin layer of dense connective tissue. Glisson’s capsule is the characteristic feature of mammalian liver. Liver is divided into two main lobes-right and left separated by the falciform ligament. The right lobe of the liver is differentiated into right lobe proper, a quadrate lobe and a caudate lobe on the posterior side. Numerous thin branched septa-like trabeculae (not very prominent in human liver) extend inwards from the Glisson’s capsule, dividing each liver lobe into numerous minute hepatic lobules. Kupffer’s cells (hepatic macrophages or stellate cells) are also present in the liver which are phagocytic cells that eat bacteria and foreign substances. A pear-shaped sac-like structure called gall bladder is attached to the posterior surface of the liver on the right side by connective tissue. Its main function is to store and concentrate the bile secreted by the liver. Liver has high power of regeneration. The blood supply to the liver from the stomach, intestines, pancreas and spleen is carried YLD the hepatic portal vein. This blood makes up 80% of blood flow through the liver. The remaining 20% is made up by blood from the proper hepatic arteries, which are responsible for nourishing the liver cells. The liver parenchymal cells (hepatocyte) are bathed in mixed blood from the hepatic portal vein and proper hepatic arteries, so that they receive nutrition from both.

s s s s s s s

Hepatic portal system The hepatic portal system (portal venous system) is formed by hepatic portal veins and its tributaries. Substances absorbed in the small intestine travel first to the liver for processing before continuing to the heart. It also includes venous drainage from the spleen and pancreas. Many drugs absorbed through GI tract are substantially metabolised by the liver before reaching general circulation. All useful and non-useful products absorbed in GI tract are processed in the liver before being either released back into the hepatic veins which join inferior vena cava or stored in the liver for later use. It helps liver in detoxification of blood. s Ducts of liver lobes are known as hepatic ducts and duct of gall bladder is known as cystic duct. The right and left hepatic

ducts join to form the common hepatic duct. The latter joins the cystic duct to form the bile duct (ductus choledochus). The bile duct passes downwards posteriorly to join the main pancreatic duct to form the hepatopancreatic ampulla (ampulla of Vater). The ampulla opens into the duodenum. The opening is guarded by the sphincter of Oddi. The sphincter of Boyden surrounds the opening of the bile duct before it is joined with the pancreatic duct. s Bile is produced in the liver and stored in the gall bladder from where it is released into the small intestine. Bile contains bile salts and bile pigments. Bile salts synthesised in the liver from cholesterol are responsible for fat emulsification and absorption. These salts are sodium glycocholate, sodium bicarbonate and sodium taurocholate. s Bile pigments include biliverdin and bilirubin which are excretory products derived from the degradation of haemoglobin. Bicarbonate ions help to neutralise the acidic chyme (semisolid and partly digested food that is discharged from the stomach into the duodenum) and provide an alkaline medium for the digestion of food in the small intestine. Bile does not contain any enzyme. &RQWGRQSDJHQR

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 Maximise your chance of success 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-X : ECOLOGY CHAPTER-13 : ORGANISMS AND POPULATIONS

Multiple Choice Questions 1. Verhulst and Pearl are associated with the equation

(K ) K −N dN = rN ( N ) dt

(N) dN K −N . = tN ( dt K )

(a) dN = rN K − N

(b) dN = tN K − N

(c)

(d)

dt

dt

2. Which one of the following correctly represents an organism and its ecological niche? (a) 9DOOLVQHULDand pond (b) Desert locust (6FLVWRFHUFD) and desert (c) Plant lice (aphids) and leaf (d) Vultures and dense forest 3. Which of the following is correct? (a) Population change = (Birth + immigration) – (death + emigration) (b) Population change = (Birth + immigration) + (death + emigration) (c) Population change = (Birth + emigration) + (death – immigration) (d) Population change = (Birth – immigration) – (death + emigration) 4. The success of mammals on earth is largely because (a) they have the ability to maintain constant body temperature

(b) they can conform to the changes in the environment (c) they can take care of their young ones as they have mammary glands to suckle them (d) they can reduce metabolic activity and go into a state of dormancy during unfavourable conditions in the environment. 5. A sedentary sea anemone gets attached to the shell lining of hermit crab. The association is (a) commensalism (b) amensalism (c) ectoparasitism (d) protocooperation. 6. Which one of the following is most appropriately defined? (a) Host is an organism which provides food to another organism. (b) Amensalism is a relationship in which one species is benefitted whereas the other is unaffected. (c) Predator is an organism that catches and kills other organism for food. (d) Parasite is an organism which always lives inside the body of other organism and may kill it. 7. Plants requiring low light intensity for optimum photosynthesis are called (a) heliophytes (b) pteridophytes (c) sciophytes (d) bryophytes. MT BIOLOGY

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8. An inhabitant of Varanasi goes to Rohtang and experiences nausea, fatigue and heart palpitations. It is because (a) he is experiencing altitude sickness (b) his RBC count is lower than required (c) he is in an area of low atmospheric pressure (d) all of these. 9. Why you never see cattle or goats browsing on weed &DORWURSLV? (a) The plant produces highly poisonous tannins. (b) The plant produces quinine which is bitter in taste. (c) The plant produces poisonous cardiac glycosides. (d) The plant bears prickles. 10. A biologist studied the population of rats in a barn. He found that the average natality was 250, average mortality 240, immigration 20 and emigration 30. The net increase in population is (a) 05 (b) zero (c) 10 (d) 15.

True or False 11. Conformers can maintain their body temperature. 12. Nyctinasty is folding of leaves in response to darkness. 13. Hygroscopic water is water present inside micropores and it is the water available to plant roots. 14. Chaperonins are heat shock proteins which protect other proteins from denaturation at high temperature. 15. Immigration is the number of individuals of same species who left the habitat during the time period under consideration. 16. Homoeostasis is the phenomenon of maintaining a constant internal environment despite of the changes in external environment. 17. Humus is dark brown amorphous gummy substance which is completely soluble in water. 18. Camouflage is the ability of animals to blend with the surroundings or background. 19. Microbes like archaebacteria live comfortably in hot springs and deep sea hydrothermal vents where temperature may exceed 100°C. 20. Mutualism is an interaction between two organisms of two different species where both the partners are benefitted but they can live without each other.

Match The Columns 21. Match Column I with Column II. Column I Column II A. Tropical zone (i) Hekistotherms B. Subtropical zone (ii) Microtherms C. Temperate zone (iii) Megatherms D. Arctic zone (iv) Mesotherms 32

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22. Match Column I with Column II. (There can be more than one match for items in Column I). Column I Column II A. Predation (i) Interaction between sea anemone and clown fish B. Commensalism (ii) Interaction between %DODQXVand&DWKDPDOXV C. Mutualism (iii) Interaction between frog and insects D. Protocooperation (iv) Interaction between Abingdon tortoise and goat E. Competition (v) Interaction between fungi and roots of higher plants (vi) Interaction between 1HSHQWKHV and insects (vii) Interaction between male bees and Mediterranean orchid  (viii) Interaction between 3OXYLDQXV DHJ\SWLXV and crocodile (ix) Interaction between %XSKDJXVHU\WKURUK\QFXV and 'LFHURVGLFRUQLV (x) Interaction between cattle egret and grazing cattle

Passage Based Questions 23.(A) Complete the given passage with appropriate words or phrases. Depending upon the ability to tolerate variations in surrounding temperature, organisms are of two types. (i) organisms can tolerate and thrive in a wide range of temperature while (ii) organisms are restricted to narrow range of temperature. Plants and large number of animals are (iii) as their body temperature varies with temperature of the environment. Such animals are also called (iv). Birds and mammals are (v) because they keep their body temperature constant despite changes in environmental temperature. They are also called (vi) . The phenomenon of maintaining a constant internal temperature despite changes in external environment is called (vii) . This is done by several means such as retaining (viii) produced by metabolic reactions, having (ix) coat, changing (x) circulation, etc. (B)

Read the given passage and correct the errors, wherever present. Plants growing in bright light are called sun plants or sciophytes while plants growing in partial shade or low intensity light are called shade plants or heliophytes. In a

forest, plants get arranged in various strata according to their shade tolerance, a phenomenon known as aestivation. Sun plants are adapted to lower temperature optimum for photosynthesis and low rates of respiration. Shade plants have high photosynthetic, respiratory and metabolic activities. The amount of flowering and fruiting is less in sun plants while it is more in shade plants.

(b) Write the equation for curve A and B. (c) Out of the two curves shown in the graph, which one is considered more realistic and why? 30.

Refer to the given graph and answer the following questions.

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. 24. Assertion : Natality increases size of population while mortality decreases size of population. Reason : Natality adds new individuals to the population and mortality removes individuals from the population. 25. Assertion : 7DPDUL[ and 3URVRSLV are used to locate ground water. Reason : 7DPDUL[ and 3URVRSLV are phreatophytes a type of xerophytes. 26. Assertion : Shark is tolerant to a wide range of salinities, while salmon is restricted to a narrow range. Reason : Shark is euryhaline whereas salmon is stenohaline. 27. Assertion : Plants need the help of animals for pollinating flowers and dispersing seeds. Reason : Plants offer rewards to pollinating animals in the form of pollen and nectar. 28. Assertion : Triangular shaped age pyramid represents a growing or expanding population. Reason : Proportion of individuals in reproductive and post reproductive age group is higher than the individual in pre-reproductive age group.

Figure Based Questions 29. Refer to the given graph and answer the following questions.

(a) Identify curve A and B regarding population growth in the given graph.

(a) Identify labelled part A, B and C in the given graph regarding the types of organisms based on their responses to various abiotic factors. (b) How do A, B and C differ from each other regarding their responses to various abiotic factors? (c) Mention the labelled part to which most of the animals and plants belong. CHAPTER-14 : ECOSYSTEM

Multiple Choice Questions 1. The breaking down of detritus into smaller pieces by detritivores is called (a) leaching (b) humification (c) catabolism (d) fragmentation. 2. If 20 J of energy is trapped at producer level, then how much energy will be available to peacock in the following chain? Plant → Mice → Snake → Peacock (a) 0.02 J (b) 0.002 J (c) 0.2 J (d) 0.0002 J 3. Which of the following is a primary consumer in a maize field ecosystem? (a) Grasshopper (b) Wolf (c) Phytoplankton (d) Lion 4. Which of the following relations is correct regarding the GPP and NPP of an ecosystem? (a) NPP = GPP – Animal consumption (b) NPP = GPP + Plant respiration (c) NPP = GPP – Plant respiration (d) NPP = GPP + Animal consumption 5. An inverted pyramid of number and an inverted pyramid of biomass are respectively seen in (a) grassland and tree ecosystem (b) sea and tree ecosystem (c) tree and sea ecosystem (d) sea and grassland ecosystem. MT BIOLOGY

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6. Which one of the following animals may occupy more than one trophic level in the same ecosystem at the same time? (a) Sparrow (b) Lion (c) Goat (d) None of these 7. Most animals that live in deep oceanic waters are (a) tertiary consumers (b) detritivores (c) primary consumers (d) secondary consumers. 8. The flow of energy among various trophic levels of an ecosystem is (a) unidirectional (b) bidirectional (c) multidirectional (d) circular. 9. The sequence of communities of primary succession in water is (a) phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and trees (b) phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and trees (c) free-floating hydrophytes, sedges, phytoplankton, rooted hydrophytes, grasses and trees (d) phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp, sedges and trees. 10. Which of the following is an ecosystem service provided by a natural ecosystem? (a) Cycling of nutrients (b) Prevention of soil erosion (c) Pollutant absorption and reduction of the threat of global warming (d) All of these

True or False 11. Standing state is the amount of inorganic nutrients present in an ecosystem. 12. The first biotic community, which develops in a bare area is called pioneer community. 13. Herbivores, consumers of first order constitute the second trophic level or T2 in an ecosystem. 14. Decomposers are animals which feed on detritus. 15. Dry deposition is input of nutrients in an ecosystem in the particulate state. 16. Pyramid of biomass is upright for aquatic habitats and inverted or spindle shaped in terrestrial habitats. 17. Psammosere is a type of xerosere in which sequence of successional stages occurs on a bare rock. 18. Trophic level efficiency is the percentage of energy converted into biomass by a higher trophic level over the energy of food resources available at the lower trophic level. 19. Consumers are also known as transducers, as they are able to change light energy into chemical form. 34

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20. Maximum productivity occurs in coral reefs, followed by estuaries and sugarcane fields.

Match The Columns 21. Match Column I with Column II. Column I A. Energy flow (i) B. Mesoecosystem (ii) C. Nanoecosystem (iii) D. Megaecosystem (iv) E. Microecosystem (v)

Column II Aquarium Forest Unidirectional Pond Ocean

22. Match Column I with Column II. (There can be more than one match for items in Column I). Column I Column II A. Gaseous nutrient cycle B. Sedimentary nutrient cycle C. Reed swamp stage of   hydrosere D. Submerged stage of hydrosere E. Floating stage of hydrosere

(i) +\GULOOD (ii) 7\SKD (iii) Hydrogen (iv) Nitrogen (v) $]ROOD (vi) Phosphorus (vii) :ROIILD (viii) Calcium (ix) 3KUDJPLWHV (x) 3RWDPRJHWRQ

Passage Based Questions 23.(A) Complete the given passage with appropriate words or phrases. (i) break down detritus into smaller pieces by a process called (ii) . (iii) and (iv) secrete enzymes which degrade detritus into simpler substances by (v) . By the process of (vi) , water soluble inorganic nutrients go down into the soil horizon alongwith the percolating water. The decomposition process leads to the formation of two products, (vii) and (viii) . Processes involved in their formation are called (ix) and (x) respectively. (B) Read the given passage and correct the errors, wherever present. Ecological pyramids were developed by Tansley. In a pyramid the various steps of a food chain are represented sequence-wise with producers at the tip, herbivores below them and top carnivores at base. An ecological pyramid can be upright-narrow base, gradually getting broader towards the tip, inverted-large base, gradually tapering towards the tip and spindle shaped-narrow in the middle, with broader part at the base and tip.

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. 24. Assertion : Gross primary productivity is more than the net primary productivity. Reason : Gross primary productivity is the amount of organic matter stored by producers per unit time and per unit area. 25. Assertion : Decomposers are known as microconsumers and reducers. Reason : Decomposers are microorganisms that are able to remove or degrade the dead bodies of other organisms. 26. Assertion : Detritivores and decomposers have no place in ecological pyramid. Reason : Detritivores and decomposers do not play any vital role in the ecosystem. 27. Assertion : The organisms of the higher trophic level are dependent for their food and energy on the organisms of the lower trophic level. Reason : The number of individuals in a higher trophic level is generally lesser than that of the lower trophic level. 28. Assertion : Sedimentary nutrient cycles are considered as perfect cycles. Reason : The reservoir for sedimentary cycles exists in the atmosphere.

Figure Based Questions 29. Refer to the given figure and answer the following questions.

(c) Calculate and draw food chains operating in the given figure. 30. Refer to the given flowchart and answer the following questions.

(a) Identify A, B, C, D and E in the given flowchart. (b) Name the reservoir pool and cycling pool for the given flowchart. (c) Briefly describe the process labelled as E in the given flowchart. CHAPTER-15 : BIODIVERSITY AND CONSERVATION

Multiple Choice Questions 1. Biosphere reserves differ from National parks and wildlife sanctuaries because in the former (a) human beings are not allowed to enter (b) people are an integral part of the system (c) plants are paid greater attention than the animals (d) living organisms are brought from all over the world and preserved for prosperity. 2. Which of the following region is regarded as the ‘cradle of speciation’? (a) Western ghats (b) North-Eastern region (c) Eastern Himalayas (d) Deccan plateau 3. In India, we find mangoes with different flavours, colours, fibre content, sugar content and even shelf-life. The large variation is on account of (a) species diversity (b) induced mutations (c) genetic diversity (d) hybridisation. 4. Which one of the following is the first National park in India? (a) Kanha National Park (b) Periyar National Park (c) Jim Corbett National Park (d) Bandipur National Park

(a) Identify the trophic levels occupied by organisms A, B, C and D in the given figure. (b) Calculate how many organisms acts both as prey and predator in the given figure.

5. Find the wrongly matched pair. (a) Endemism - Species confined to a region and not found anywhere else (b) Hotspots - Western ghats (c) Sacred groves - Jaintia hills of Meghalaya (d) ,QVLWX conservation - Zoological parks

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6. Which of the following is not an invasive species? (a) 3DUWKHQLXPK\VWHURSKRUXV (b) 2FLPXPVDQFWXP (c) /DQWDQDFDPDUD (d) (LFKKRUQLDFUDVVLSHV 7. The relation between species richness and area is described on a logarithmic scale by the equation [where S = species richness, A = area, Z = slope of the line (regression coefficient), C= Y-intercept] (a) log S = log C – Z log A (b) log S = Z log A (c) log S = log C + Z log A (d) log S = log C 8. Biodiversity of a geographical region represents (a) endangered species found in the region (b) the diversity in the organisms living in the region (c) genetic diversity in the dominant species of the region (d) species endemic to the region.

18. International Crop Research Institute for Semi-Arid Tropics (ICRISAT) in Hyderabad conserve germplasm of groundnut, pigeon pea, chick pea, pearl millet and sorghum. 19. Myers initially identified 12 hot spots with 14% of plant species in an area of only 0.2%. 20. Snow leopard (/HR XQFLD) was initially listed as indeterminate but in 1970 it was listed as endangered.

Match The Columns 21. Match Column I with Column II. Column I A. Extinct species (i) B. Vulnerable species (ii) C. Genetic diversity (iii) D. Exotic species (iv) E. Endangered species (v)

22. Match Column I with Column II. (There can be more than one match for items in Column I). Column I Column II

9. Dodo, passenger pigeon and Steller’s sea cow became extinct in the last 500 years due to (a) habitat destruction (b) over-exploitation (c) bird-flu virus infection (d) pollution.

A. B. C. D. E.

10. First ‘Earth Summit’ for ‘Convention on Biological Diversity’ (CBD) was held at (a) Johannesberg (2002), S. Africa (b) Rio de Janeiro (1992), Brazil (c) Dehradun (1992), India (d) New York (2000), U.S.A.

True or False 11. Maximum biodiversity occurs in Amazon rainforest of South America. 12. Wildlife sanctuaries are meant for protection of both flora and fauna. 13. Rivet popper hypothesis, proposed by Paul Ehlrich, describes the effect of decrease in biodiversity on an ecosystem. 14. Orthodox seeds are those seeds which are not able to germinate on reducing the moisture content (upto 5%) and on exposure to low temperature (–10° to –20°C). 15. Water hyacinth ((LFKKRUQLDFUDVVLSHV) is native species of India which help in reducing pollution. 16. Extinction vortex is a combination of genetic and demographic factors. 17. Jaintia and Khasi hills are sacred groves found in Rajasthan. 36

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Column II 5DXZROILDYRPLWDULD %HQWLQFNLDQLFREDULFD /DQWDQDFDPDUD 5DSKXVFXFXOODWXV $QWLORSHFHUYLFDSUD

Biosphere reserves ,QVLWX conservation ([VLWX conservation Coextinction Rare species

(i) (ii) (iii) (iv) (v) (vi) (vii) (viii) (ix) (x)

1HRIHOLVQHEXORVD