o1384244546tBio Solutions 6-10 XI

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SampleQuestion Papers

OSWAAL BOOKS

Class

Biology

Solutions

Strictly Based on Latest Syllabus Issued by CBSE

for 2014 Examination



CONTENTS

Solutions

Sample Question Paper 6 1 - 7







Sampl e Question Paper (Solv ed) | 1

SAMPLE QUESTION PAPER–6

Section-A

1. Ident ificat ion means a ssigning a n organ ism to a par ticular ta xonomic group. 1

2. The brown colour of these algae r esults due to dominance of xant hophyll pigment fucoxant hin,

w hich masks the oth er pigments. 1

3. (i) Aleurone la yer a nd (ii) Scut ellum. ½+½

4. A cement ing lay er of pectic mat erials holding together t he primary cell wa lls of a dja cent cells is

called middle lamella. 1

5. ETS is opera tive in th e inner mitochondria l membrane. 1

Section-B

6. The four categories of bacteria based on t heir sha pes are :

(i) Spher ical coccus,(ii) Rod-shaped bacillus,

(iii) Comma -sha ped vibrium an d spira l spirillum. ½×4=2

Flagellum

SpirillaCocci

Spore

Vibrio

7. (a) In roots, the protoxylem lies towa rds periphery an d metaxylem lies towa rds th e centre. Such

ar ra ngement of prima ry xylem is called exa rch condition of xylem.(b) In stems, the protoxylem lies towa rds th e centre a nd metaxy lem lies towa rds the periphery.

Such a rra ngement of primary xylem is called enda rch condition of xylem. 1+1=2

8. (i ) Triglycerides a re glycerides in which the glycerol is es ter if ied w i th three fa t t y a c ids .

(i i) They ar e the main const i tuents of vegetable oi l and a nimal fa ts .

(i i i) G lycerol is a 3C-a lcohol with 3-OH g roups tha t serve a s binding sites. 2

OR

Haplontic life cycle

(a) The ha ploid phase is dominant an d the diploid phase is represented only by the zygote wh ich

und ergoes meiosis.

(b) Embryo and sporophyte are absent .

Exa mple – alga e (Spirogyra ).

Diplontic life cycle

(a) The diploid phase is domina nt a nd few celled gam etophytes a re the only haploid phase in the

life cycle.

(b) Zygote develops into an embryo an d th en into a sporophyte.

Exa mples – Angiosperms a nd G ymnosperms. ½×4=2



2 | Oswaal CBSE Bi ology, Cl ass–XI

(i ) I t resul ts from hyposecret ion of insul in.

(i i) I ts symptoms show h igh blood glucose

level, breakdow n of muscle tissue, loss of

weight a nd t i redness.

It results from hy persecretion of insulin.

It s sym ptoms show low blood glucose level,

hunger , sweat ing, i rr i tabi l i ty and double

vision.

½×4=2

Section-C

11. Primary meristem Secondary meristem

(i ) I t develops from promeris tem.

(i i) I t i s formed in the beginning .

(i ii ) I t resul t s in pr imary growth .

(iv) I t forms primary t i ssues except intrafasci-

cular cambium.

It develops from permanent t i ssue that

regains the power of division.

It is formed in later sta ge.

I t resul ts in secondary growth.

It forms seconda ry t issues.

1+1+1=3

12. The peculiar cha ra cteristics of the phylum chorda ta ar e :

(i) The notochord is sti ff and flexible rod of t issues lying ventra l to nerve cord.

(i i) All the chorda tes are triplobla stic, coeloma te an d bilat erally symmetrical .

(i i i) They possess a post a na l ta i l and closed blood va scular system.

(iv) P resence of a dorsal hollow nerve cord and pa ired phary ngeal gil l sl its . 1+1+1=3

13. (i) Ea ch muscle is made of man y long, cylindrical fibres arra nged in par allel ar ra ys. These fibres

a re composed of num erous fine fibrils, called my ofibrils.

(i i) Muscle fibres cont ra ct (shorten) in response to stimulat ion, t hen rela x (lengthen) and retur n

to their un cont ra cted stat e in a coordinat ed fashion. Their action moves the body to a djust t o

the changes in the environment and to maintain the positions of the various parts of the

body.

(iii)In genera l, muscles play a n a ctive role in a ll th e movement s of th e body. Mu scles ar e of th ree

types, skeletal , smooth, a nd car diac. 1+1+1=3

14. The va rious fun ctions of epithelial tissues a re :

(a) Protection – The epithelial tissue protects the underlying tissue from injury, chemicals,

bacteria etc.

(b) Sensation – The specia lized epithelia l tissue consistin g of sensory n erve ending s ar e found

in th e skin, eyes, nose, ears a nd t he tongue.

(c) Secretion – The epithelial tissue secretes definite chemical substances such as enzymes,

hormones and lubricating fluids.

(d) Absorption – The epithelial t issue l ining the small intestine absorb nutrients from the

digestion of food.

9. White matter Grey matter

(i ) I t cons i s t s o f l a rge myelina ted f ib res,

some un myelinated fibres a nd g lial cells.

(i i) I t forms a layer between two areas of grey

mat ter in the b ra in and enc loses the

column of grey ma tt er in the spina l cord.

I t cons i s t s o f nerve ce l l bodies and the i r

nuclei.

It forms th e surface layer of the brain, r egions

deep in the bra in a nd t he centr al column of the

spina l cord.

½×4=2

10. Hyperglycemia Hypoglycemia




(e) Excretion – The epithelial tissue in kidney excretes waste products from the body and

reabsorbs needed mat erials from the urine.

(f) Diffusion – Simple epith elium helps in diffusing ga ses, liquids, n utr ients etc. ½×6=3

15. In pa chyten e stag e of prophase I in Meiosis I, the bivalent chromosomes clearly a ppear a s tetra ds.

This sta ge is cha ra cterized by t he appeara nce of recombinat ion n odules, th e sites a t w hich crossing

over occurs betw een non-sister chroma tids of th e homologous chromosomes.

Crossing over is t he exchan ge of genetic mater ial betw een tw o homologous chromosomes.

Cr ossing over is also an enzyme-mediat ed process and th e enzyme involved is called recombina se.

Significance :

Crossing over leads t o recombinat ion of g enetic materia l on th e t wo chromosomes.

Recombina tion betw een homologous chromosomes is completed by th e end of pa chyten e, lea ving

th e chromosomes linked at t he sites of crossing over. 1+1+1

16. The chloroplasts of the green pla nt s a re found in th e mesophy ll cells of th e leaves. These a re lens-

sha ped, ova l, spherical, discoid or even ribbon-like org an elles ha ving va ria ble lengt h (5-10 mm)

an d w idth (2-4 mm). The chloroplasts a re double membra ne bound. Of th e tw o, the inner chloropla st

membra ne is relat ively less perm eable. The space limited by the inner m embra ne of the chloroplast

is ca lled the stroma . A number of orga nized flat tened membran ous sacs called the th ylakoids are

present in t he stroma (Figure). Thyla koids a re a rra nged in s ta cks l ike the piles of coins called

gra na (singular : gra num) or the inter-gra na l thylakoids. In a ddition, there are flat membran ous

tubules ca lled the str oma la mellae connecting th e thyla koids of the different g ra na . The membran e

of the th yla koids encloses a spa ce ca lled a lumen. The str oma of the chloroplast cont ain s enzymes

required for the synt hesis of carbohydra tes an d proteins. It also conta ins small , double-stra nded

circular D NA molecules an d ribosomes. Chlorophyll pigments a re present in th e thyla koids. The

ribosomes of the chloroplast s a re sma ller (70S) tha n t he cyt opla smic ribosomes (80S). 3

Outer membrane

Inner membrane

St romal L amella

G r a n a

St roma

Ribosomes

Sta rch granule

Lipid droplet

OR

Ovary

Oviduct

Common Oviduct

or vagina

Collat erial g land s

Genita l cham ber

Vestibulum

Geni ta l

pouch

Supermatheca

Gonapophysis

(b)3




17. The pigments ar e organ ized int o tw o discrete photochemical l ight h ar vesting complexes (LH C)within t he PS I a nd P S I I . These are named in the sequence of their discovery , and not in thesequence in w hich t hey function during th e l ight reaction. The LH C a re ma de up of hun dreds ofpigment molecules bound t o proteins. E a ch photosystem ha s all th e pigmen ts (except one moleculeof chlorophyll a ) forming a l ight ha rvesting syst em also called an tenna e. These pigments help toma ke photosynt hesis more efficient by a bsorbing different w av elength s of light.

The single ch lorophyll a molecule forms th e reaction cent re. The rea ction cent re is different inboth the photosystems. In PS I the reaction centre chlorophyll a have a n a bsorpt ion peak a t700 nm, hence is called P700, while in P S I I i t h as a bsorption maxima at 680 nm, an d is calledP 680. 3

18. G rowt h is regar ded as one of the most funda menta l and conspicuous cha ra cteristics of a l ivingbeing. G rowth can be defined as an irreversible perman ent increase in size of an orga n or i tspar ts or even of an individual cell. P lant growt h is unique because pla nts r etain th e capa city forun limited growt h th rough out th eir life. This a bility of the plan ts is due to th e presence of meristemsa t certa in loca tions in th eir body. The cells of such meristems h a ve the capa city to divide an d self-perpetua te. G rowt h, a t a cellular level , is principally a consequence of increase in the a mount ofprotoplas m. Since increa se in protoplasm is difficult to mea sure directly, one generally mea suressome quantity which is more or less proportional to i t . Growth is, therefore, measured by avar iety of para meters . 3

19. Sy stemic circula tion refers to th e flow of oxygena ted blood from the left vent ricle to a ll par ts ofthe body a nd t he flow of deoxygena ted blood from all par ts except lung s of the body to the righ tatr ium.

The importa nce of circula tion is :(a) To supply oxygen an d nu tr ient s to a l l parts of the body.

(b) To remove car bon d ioxide an d other meta bolic w a stes from th e body t issues.

Vent ricles ar e the pumping chambers a nd th ey ha ve to exert more pressure for pumping theblood to var ious part s and so a re more muscular. The atr ia a re the receiving cha mbers an d th eyha ve to pump the blood only th e respective ventricles a nd so ha ve less muscular wa ll. 1+1+1=3

20. A nerve impulse a rriving a t the neur omuscular junction initiates th e contr a cti le response. Aneurotransmitter released at the neuromuscular junction enters the sacromere through itsmembran e chan nel. The opening of the cha nn el results in the inflow of sodium ions inside thesacromere an d generat es a component of the thin fi lament. As a result of conformational chan gesin th e troponin, the a ctive sites on the F -a ctin a re exposed. These a re th e a ctive sites specific tomyosin head, w hich show myosin-dependent ATP ase a ctivity. The myosin head a cts as h ooksan d a tt ach to F-a ctin to form bridges. 3

21. In sulin is a peptide hormone secret ed by â-cells of th e pan creas.Functions of Insulin :

It is a hy poglycemia hormone, i .e. it redu ces th e level of glucose in the blood by stim ula ting th eupt a ke an d utiliza tion of glucose by tissue cells.

It acts on th e hepat ocyt es an d st imulat es conversion of glucose to glycogen (glycogenesis). D eficiencyof insulin cau ses hyperglycemia a nd prolong ed hyper glycemia leads t o a complex disorder calledDi abetes mell i tu s . 1+1+1=3

22.

Radial

Xylem

Phloem

Phloem

Xylem

Conjoint closed

Phloem

Cambium

Xylem

Conjoint open1+1+1=3

23. (1) Appreciat e the beaut y , h ar mony a nd equilibrium of nat ure.

(2) Don’t interfere, inva de or distur b the component s of na tur e.

(3) Ha rness r esources without t i l t ing ba lance.

(4) Don’t h un t.

Values – Ca re, respect an d concern for nat ure a nd fellow beings. 1×3+1=4




Section-D

24. (i) Ca millo Golgi (1898) first observed densely st ained ret icular structur es near t he nucleus.

These were la ter n a med G olgi bodies aft er him. They consist of ma ny fla t, disc-sha ped sacs or

cisterna e of 0.5 m to 1.0 m diamet er.

(i i) These are sta cked para llel to each other. Varied number of cisternae is present in a G olgi

complex. The G olgi cisterna e ar e concentrically a rra nged n ear the n ucleus w ith d istinct convex

cis or the forming face an d concav e t rans or the ma turin g face. The cis and the t rans faces of

the orga nelle ar e entirely different , but int erconnected.

(iii)The G olgi appa ra tus pr incipally performs th e function of packag ing ma teria ls, to be delivered

eith er to th e intra -cellular ta rgets or secreted outside th e cell. Ma terials t o be packa ged in

the form of vesicles from the ER fuse with the cis face of the Golgi apparatus and move

towar ds the maturing face.

(iv) This explains w hy the G olgi appa ra tu s remains in close association w ith t he endoplasm ic

ret iculum . A nu mber of proteins syn th esized by ribosomes on the end opla smic reticulum ar e

modified in t he cisterna e of the G olgi appa ra tu s before they a re released fr om its t rans face.

G olgi appa ra tus is the importan t si te of format ion of glycoproteins a nd glycolipids.

Cisternae

4+1=5

OR

25. The following steps in t he respirat ory process ar e to relea se and uti l ize the energy stored in

NADH + H + and FADH2. This is accomplished w hen t hey a re oxidised thr ough th e electron tra nsport

system a nd t he electrons are passed on to O2 resulting in th e forma tion of H 2O.

(i) The metabol ic pathw ay, through w hich th e electron passes from one carr ier to another , is

called the electron transport system (ETS) and i t is present in the inner mitochondrial

membrane. Electrons from NADH pr oduced in the mitochondria l ma tr ix during citric acid

cycle are oxidised by a n NADH d ehydrogena se (complex I), a nd electrons a re then tra nsferred

to ubiquinone located within the inner membrane. Ubiquinone also receives reducing

equivalents via FADH 2 (complex II) tha t is genera ted during oxidat ion of succinat e in the

citric a cid cycle.

(i i) The reduced ubiquinone (ubiquinol) is th en oxidised w i th t he t ra nsfer of electr ons t ocytochrome c via cytochrome bc 1 complex (complex I II ). Cy tochrome c is a small protein

PROPH ASE - I I ME TAPHASE - II AN AP H AS E - I I TE L OP H A S E - I I

haploid

number (n)

of unduplicated

chromosomes




at ta ched to th e outer surfa ce of the inner membra ne a nd a cts as a mobile carrier for tra nsferof electr ons between complex III a nd I V.

(iii) Complex IV refers to cytochrome c oxida se complex conta ining cytochromes a a n d a3 , a n dtw o copper centres. When t he electrons pa ss from one ca rrier t o an other via complex I to IVin th e electron tr a nsport chain, they a re coupled t o ATP synt ha se (complex V) for theproduct ion of ATP from ADP an d inorga nic phospha te. The nu mber of ATP moleculessynt hesized depends on t he na tu re of the electron donor. Oxidat ion of one molecule of NADHgives rise t o 3 molecules of ATP , w hile th a t of one molecule of FADH 2 produ ces 2 molecules

of ATP .(iv) Although the a erobic process of respira tion ta kes place only in the presence of oxygen, t he

role of oxygen is limited to th e termina l sta ge of the process. Yet, th e presence of oxyg en isvital , since it dr ives the w hole process by r emoving hy drogen from the system. Oxygen a ctsas th e final hydrogen a cceptor.

(v) Un like photophosphorylation where i t is the l ight energy t ha t is uti l ized for th e production ofproton g ra dient required for phosphorylat ion, in respira tion i t is the energy of oxidation-reduction utilized for t he sam e process. It is for t his rea son tha t t he process is ca lled oxida tivephosphorylation. 1×5=5

OR

(a) (i ) Auxin – Indole B utyr ic a cid

(ii) Et hy lene

(iii) Cyt okinins(iv) Abscisic a cid

(v) G ibberellins

(b) It r efers to the phenomenon in which a plant detects and responds to the relative length ofday an d n ight for some of its ph ysiological functions. 1×5=5

26. (1) Ea ch kidney ha s near ly one million complex tubular structures called nephrons w hich a re th efunctiona l units.

(2) Ea ch nephron ha s two parts – the glomerulus and t he renal tubule. G lomerulus is a t uft ofcapillaries formed by th e afferent a rteriole – a fine bra nch of renal art ery. B lood from th eglomerulus is carr ied aw ay by an efferent ar teriole.

(3) The rena l tubule begins w ith a double w alled cup-like structure ca lled B owma n’s capsule,w hich encloses the glomerulus.

(4) G lomerulus along with B owma n’s capsule is called the malpi ghian body or r enal cor puscle .The tubule continues further to form a highly coiled network –proximal convoluted tubule(PC T).

(5) A ha irpin sha ped Henle’s loop is the next part of the t ubule wh ich h as a descending a nd a nascending l imb. The a scending l imb continues as a nother highly coiled tubular region calleddista l convoluted tu bule (DC T). The DC Ts of ma ny n ephrons open into a str a ight tub e ca lledcol lecti ng du ct , man y of which converge an d open into the rena l pelvis thr ough medullarypyra mids in the calyces.

Afferentarteiole

Glomerulus

Bowman'scapsule

Descending limbof loop of h enle

Ascending limbof loop of h enle

Va sa recta

Henle'sloop

Efferent

arteriole

Proximalconvoluted

tubule

Distal

convoluted

tubule

Collecting

duct




(6) The Ma lpighia n corpuscle, P CT a nd D CT of the nephron a re si tua ted in the cortical r egion of

the kidney w herea s the loop of Henle dips into the medulla. I n ma jority of nephrons, th e loop

of Henle is too short an d extends only very l i t t le into the medulla.

(7) Su ch nephrons a re called cortical nephrons. I n some of the nephr ons, the loop of Henle is very

long an d ru ns deep into th e medulla. These nephrons a re called juxta medullary nephrons.

The efferent ar teriole emerging from the glomerulus forms a fine capillary netw ork ar ound

the r enal tu bule called the peritubular ca pil laries.

(8) A minute vessel of this netw ork runs para llel to the H enle’s loop forming a ‘U ’ shaped vasa recta . Vasa r ecta is absent or highly redu ced in cortical nephrons. 4+1=5

OR

A simple tissue is ma de of only one t ype of cell. The va rious simple tissues in pla nt s a re par enchyma ,

collenchyma an d sclerenchyma.

Parenchyma forms t he ma jor component w ithin orga ns. The cells of the par enchym a a re genera lly

isodiametric. They m a y be spherical , oval , round, polygonal or elongat ed in sh ape. Their w a lls

ar e th in a nd mad e up of cellulose. They m ay either be closely packed or ha ve small intercellular

spa ces. The paren chyma performs var ious funct ions like photosynt hesis, storag e, secretion.

Intercellular

space

Thickened corners

Protoplasm

Vacuole

Cell wal l

The collenchyma occurs in layers below th e epidermis in dicotyledonous plan ts. It is found

either a s a h omogeneous lay er or in pa tches. It consists of cells w hich are m uch thickened at the

corn ers du e to a deposition of cellulose, hemicellulose an d pectin. Collenchyma tous cells may be

oval, spherical or polygona l an d often cont a in chloroplasts. These cells assimilate food w hen t hey

cont ain chloropla sts. I ntercellular spaces are absent. They provide mecha nical support to th e

growing part s of the plant such a s young stem a nd petiole of a leaf.

Sclerenchyma c o n s i s t s o f l o n g ,

narrow cells with thick and l ignified

cell walls having a few or numerous

p i t s . T h e y a r e u s u a l l y d e a d a n d

without protoplasts. On the basis of

var iation in form, structur e, origin and

development, sclerenchyma may be

either fibres or sclereids.

The fibres ar e thick-w a lled, elongat edand pointed cells, generally occuring

in groups, in va rious part s of the plant .

The sclereids are spherical, oval or

cylindrical, high ly thickened dea d cells

w ith very n ar row cavities (lumen).

These are commonly found in t he fruit w alls of nuts; pulp of fruits l ike guava , pear a nd sa pota;

seed coats of legumes an d leaves of tea. Sclerenchyma provides mecha nical support to organ s.

3+2=5

Lumen

Thick

Cell wall

A fibre

A Sclereid

Lumen

Pi thThick

cell wa ll





Section-A

1. These are ar chaebacteria. S ince they l ive and gr ow in high sa line or salty environments they a recalled ha lophiles. 1

2. The stomata l aperture, gua rd cells and the surr ounding subsidiary cells together ar e called stomata l

apparatus . 1

3. The age of a tr ee can be determined by counting a nnu al grow th r ings in the lower part of the

stem. 1

4. P otas sium is involved in ma ny phy siologica l processes like respira tion, photosynt hesis, stomat al

movement a nd protein synthesis. 1

5. It prevents enzyma tic hydrolysis of stored food a nd enables the seed to survive a long period of

dormancy. 1

Section-B

6. Head

Collar

Ta il fibres

(b)

Sheath

2

OR

Sporophyte

Gametophyte

Capsule

Seta

Leaves

Main axis

Rhizoids

2

7. Calcium :

(a) For t he format ion of spindles during cell wa ll.

(b) For t he forma tion of middle la mella.




Zinc :

(a) For t he synt hesis of aux in.

(b) For a ctiva tion of ca rboxylas es. 2

8. It refers to th e deposits of the indest ruct ible siliceous cell w a ll of diat oms in the ocea n floor.

Uses :

(i ) As a n a bsorbent for l iquid ni troglycerine to make explosives.

(i i) For f il ter ing t he l iquids in suga r fac tor ies.(i i i) As inert extender in paints.

(iv) For insulat ion in boi lers and blas t furnace.

(v) In pow dered form a s a bra sive in silver polish a nd toot h pa st e. (Any tw o) 2

9. These are the structures which hold the cells of a t issue together, when they are not widely

separa ted by extr acellular ma ter ial. The th ree types of cell junctions a re : Tight junctions, Adher ing

junctions and G ap junctions. 2

10. Division of labour is t he phenomenon in w hich different cells or t issues of a multicellular organ ism

perform d ifferent life functions. Multicellular organ isms ha ve cells organ ized into tissues, orga ns,

organ sy stem, each of wh ich performs a part icular fun ction. Exa mple – al imenta ry can al helps in

digestion. 2

Section-C11. Functions of potassium :

(i ) In opening and clos ing of stomata .

(i i) Act ivates a number of enzymes.

(i i i) Inv olved in protein synth esis.

(iv) Mainta ins turgidity of cells.

(v) Ma int a in s a n ion-ca t ion ba la nce of cells. (An y tw o)

Symptoms :

(i ) In terve ina l ch loros is .

(i i) Scorched leaf t ips.

(i i i) Shorter internodes.

(iv) D isin tegra t ion of pla st ids. (An y on e) 3

12. C3 pathway C4 pathway

(i) The prim a ry a cceptor of Ru B P . The pr ima ry a ccept or is P EP .

(i i) The f ir s t product is phosphoglyceri c ac id . The fi r st product i s oxa loacet i c ac id .

(ii i) Th e e n zy m e i s s en s it i v e t o h i g h t e m p er - Th e en z y me is n ot m u ch a f f ect ed b y ox y gen

a ture a nd oxygen concent ra t ion. concentra t ion.

(iv ) Th e p a t h w a y be com es s a t u r a t ed a t h ig h er Th e p a t h w a y b ecom es sa t u r a t e d a t a l ow e r

concent ra t ion of ca rbon dioxide. concent ra t ion of ca rbon dioxide.

(Any th ree) 3

13. Chondrichthyes Osteichthyes

(i) Th e en doskelet on is ca r tila gen ou s. Th e en doskelet on i s bon y.

(ii) Mou th is vent r a l. Mou t h is t ermin a l.

(iii) Ta il fin is h eter ocerca l. Ta il fin is homocerca l.

(iv) Air bla dder is a bsent . Air bla dder is present .

(v) Operculu m is a bsent . Oper culum is present .

(vi) F er t iliza t ion is in tern a l. Fer t iliza t ion is extern a l.

½×6=3




14. ATP is syn th esized wit h t he h elp of complex V (ATP synt ha se). Complex V consists of F0 – F 1

component s. F 0 is an in tegra l membra ne protein complex tha t a ct as the chan nel through w hich

the proteins pass across the membrane into the matrix. The passage of protons through the

cha nn el is coupled to th e ca ta lyt ic site of F1 componen t a nd one molecule of ATP is syn th esized

for every 2H + pass ing through F 0. 3

15. It is a t ype of cell division w here th e number of chromosomes is reduced t o half in the d aug ht er

cells.

Significance :(i) It ensur es the maintena nce of a consta nt chromosome number, chara cteristic of a species.

(i i) The crossing over results in va riations of genetic cha ra cters in th e progeny; var iat ion is

necessary for survival of species and i t is t he ra w ma terial for evolution. 1+2=3

16. Actin fi lament contain three proteins namely, actin (F-actin and G-actins), tropomyosin and

troponin. Ea ch actin fi lament consists of two F-a ctin wh ich a re helically w ound to each other.

Each F-actin is a polymer of globular actin. Two filaments of tropomyosin also run close to F-

actins t hroughout t heir length . Troponin is a complex protein found a t regula r interva ls on t he

tropomyosin. In the react ing s ta te , a subuni t of t roponin masks the act in-binding s i te of

myosin. 3

17. It is the phenomenon in which a substance closely resembling the substrate in i ts molecular

stru cture competes wit h i t for th e active site on th e enzyme. Eg – Ma lona te resembles succina te

in i ts str ucture a nd inhibits t he action of succina te dehyd rogenase. Competit ive inhibition isused in th e contr ol of bacteria l path ogens. 3

18.

LabiumMaxilla Maxilla

LabrumGrinding

regionIncisingregionMandible

Hypopharynx

Mandible

3

OR

Endosperm

ii)

Coleoptile

Plumule

Radicle

Coleorhiza

Seed coat

&

fruit - wall

i)

3



Sampl e Questi on Paper (Solved) | 11

19. Epiglottis

Larynx

Trachea

P leural membranes

AlveoliP leural fluid

Diaphragm

Lung

Cut end of lib

Bronchus

Bronchiole 3

20. All chorda tes ha ve a n otochord, but only in vertebra tes, th e notochord is replaced by vertebra l

column. Since vertebrat es have a n otochord in the embryonic sta ges they a re chorda tes. So all

the vertebra tes are chordat es but not a l l chordat es are vertebrates . Sub phylum vertebrat a —

(1) Agna tha an d (2) G na thostomat a. 3

21. When a protein ha s man y subunits (polypeptide cha ins), each ha ving a primary , secondary or

tert iary str ucture of i ts own , the protein is said to be in i ts qua terna ry str ucture. Exa mples –

Myoglobin, In sulin, Ha emoglobin. 3

22. Rods Cones

(i) Th e se a r e m ea n t f or v is ion in d im lig h t . Th e se a r e me a n t f or vi sion in b rig h t lig h t .

(i i) They do not have the ability to make coloured They have the abil ity to make coloured image.

image.

(i i i) These contain t he visual pigment rhodopsin. These conta in th e pigment iodopsin.

3

23. G an ga w a ter ha s been immensely polluted due to :

* I ndust r ia l w a st e * Sew a ge

* Immenss ion o f idol s and o ther re li g ious i tems . * Fer t i li zers used in excess .

* B at hing & w ashin g (Us age of detergent s)

Value – Ca re , Concern , Ra tiona l use of na tur al resource. 3+1=4

Section-D

24.Rough endopla smic

reticulumLysosomeSmooth

endoplasmic

reticulum

Plasmodesmata

Microtubule

Nucleus

Nucleolus

Golgi

a p p a ra t u s

Nuclearenvelope

P l a s m a

membrane

Vacuole

Middle lam ella

Cell wa l l

Mitochondrion

RibosomesChloroplast

Cytoplasm

Peroxisome

5




OR

Frontal bone

Occipital

condyle

Occipital

bone

Temporal

bone

P a r i e t a l

bone Sphenoid bone

Et hmoid bone

La crima l bone

Na sal bone

Zygomat ic bone

Maxilla

Mandible

Hyoid bone

5

25. (1) Living orga nisms have the capabil i ty of extra cting energy from oxidisable substa nces and

store this in t he form of bond en ergy. S pecial substa nces like ATP carry this energy in th eir

chemical bonds.

(2) The process of wh ich ATP is synt hesized by cells (in mitochondr ia a nd chloroplasts) is na medphosphorylation. Photophosphorylation is the synthesis of ATP from ADP and inorganic

phospha te in the presence of l ight .

(3) When only P S I i s funct iona l , the electron is c irculated w i thin the photosystem and the

phosphorylat ion occurs d ue t o cyclic flow of electrons. A possible loca tion w here t his could be

ha ppening is in th e stroma la mellae. While the membra ne or lamellae of the gra na ha ve both

P S I a nd P S II the stroma lamellae membranes lack PS II as w ell as NADP reducta se enzyme.

(4) The excited electron does not pass on to NADP + but is cycled back to the PS I complex

thr ough th e electron tra nsport chain. The cyclic flow hence, results only in th e synt hesis of

ATP , but not of NADP H + H + .

(5) Cyclic photophosphorylat ion a lso occurs wh en only l ight of wa velength s beyond 680 nm a re

ava ilable for excitat ion.

Ph otosys tem I

e- a cceptor

Light

A D P

+ U P

A T P

Electron

transport

system

Chlorophyll

P 7005

ORMineral nut ri t ion refers to how plant s obta in their nut rient elements from soil, w at er or a ir and

use them for th eir growth an d development.

Essential elements :

Most of th e minerals present in soil can ent er plant s th rough roots. In a ddition t o the 17 essentia l

elements, th ere a re some beneficial element s such a s sodium, silicon, coba lt a nd selenium. They

ar e required by higher plan ts. Essent ial elements can a lso be grouped into four broad cat egories

on the ba sis of th eir diverse functions. These categ ories a re :




(i) Essentia l element s as components of biomolecules an d hence structu ra l elements of cells

(e.g., carbon, hydr ogen, oxygen an d nitrogen).

(i i) Essentia l element s tha t a re components of energy-relat ed chemica l compounds in pla nts

(e.g., m ag nesium in ch lorophyll a nd phosphorous in ATP ).

(i i i) Essentia l element s tha t a ctivate or inhibit enzymes, for example Mg2+ is an activator for

both ribulose biphosphate carboxylase-oxygenase and phosphoenol pyruvate carboxylase,

both of wh ich a re cri t ical enzym es in photosynt hetic car bon fixat ion; Zn 2+ is an activa tor of

alcohol dehy drogenase a nd Mo of nitr ogena se during n itrogen metabolism.(iv) Some essential elements can a lter the osmotic potential of a cell. P ota ssium play s an importan t

role in t he opening a nd closing of stomata . 5

26. (1) ECG is a gra phica l representat ion of the electr ical ac t iv i ty of the heart during a cardiac

cycle. A pat ient is conn ected t o the ma chine with th ree electrical leads (one to each w rist a nd

to the left a nkle) tha t cont inuously monitor the hea rt a ctivity. For a detailed evalua tion of

the hea rt ’s function, mult iple leads a re at ta ched to the chest region. Here, w e will ta lk only

about a s t andard ECG .

(2) Ea ch pea k in the ECG is ident i f ied wi th a let ter from P to T tha t corresponds to a speci f ic

e lec t r i ca l ac t iv i t y o f the hear t . The P-wave represents the e lec t r i ca l exc i t a t ion (or

depolar isation) of th e atr ia, w hich leads to th e contra ction of both the a tr ia. The QRS complex

represent s th e depolarisat ion of th e ventricles, wh ich initia tes th e ventricular contra ction.

(3) The contra ction sta rts shortly a fter Q and ma rks the beginning of the systole. The T-w averepresents t he retu rn of th e ventr icles from excited to norma l stat e (repolarisa tion). The end

of the T-w a ve ma rks t he end of syst ole.

(4) Obviously, by count ing the n umber of QRS complexes tha t occur in a given time period, one

can determine the heart beat ra te of an individual .

(5) Since the ECG s obtained from di f ferent individuals ha ve roughly the same sha pe for a given

lead configur a tion, any deviat ion from this shape indicat es a possible a bnorma lity or disease.

R

P Q ST

5

OR

(1) Heart i s si tuated in the t horacic cavi ty , in between the tw o lungs, s l ight ly t i l ted to the lef t . I t

ha s th e size of a clenched fist. It is protected by a double wa lled membra nous bag, perica rdium,

enclosing the pericardia l fluid.

(2) Our heart ha s four chambers , tw o rela t ively smal l upper cha mbers cal led a tr ia a nd tw o

larg er lower cha mbers called vent ricles.

(3) A thin, muscular w all called the inter-atr ial septum separ ates the right and t he left a tria,

wh ereas a th ick-w alled, the inter -ventricular septum, separa tes the left and th e right vent ricles.

(4) The at r ium an d th e ventr ic le of the same s ide are a lso separa ted by a thick f ibrous t issuecalled t he a trio-ventricular septum.

(5) Ea ch of these septa is provided with an opening through wh ich the tw o chambers of the same

side are connected. The opening betw een th e right a trium a nd t he right ventricle is guar ded

by a va lve formed of thr ee muscula r flaps or cusps, the tr icuspid va lve, wh ereas a bicuspid or

mitra l va lve gua rds th e opening betw een the left at rium a nd th e left ventricle.

(6) The openings of the r ight a nd th e lef t ventr ic les into the pulmonar y a r tery a nd t he aorta

respectively a re provided w ith t he semiluna r va lves. The va lves in t he hea rt al lows th e flow

of blood only in one direction, i.e., from the at ria t o the ventricles and from the ventricles to

the pulmona ry a rtery or aort a. These valves prevent any ba ckwa rd flow.




(7) The entire hea rt is made of car diac muscles. The w alls of ventricles a re much t hicker th an

tha t of the a tria . A specia lized cardia c musculat ure called t he nodal t issue is also distributed

in the h eart . A pat ch of this t issue is present in the r ight upper corner of the righ t a tr ium

called th e sino-a tr ial n ode (SAN).

(8) Another ma ss of th is t issue is seen in the lower left corner of the right at rium close to the

atrio-ventricular septum called the atrio-ventricular node (AVN). A bundle of nodal fibres,

a tr io-ventr icula r bund le (AV bundle) continues from th e AVN which pa sses through th e at rio-

ventr icular septa t o emerge on the top of the inter -ventr icula r septum a nd immediat ely divides

into a right a nd left bund le.

(9) These bra nches give rise to minut e fibres throughout t he ventricular m usculat ure of the

respective sides an d a re called purk inje fibres. These fibres a long w ith r ight an d left bund les

ar e know n as bundle of H is. 3

Aorta

Pulmonary

Left a t r ium

B undle of his

Lef t ventric le

Apex

Vena cava

Sino-at rial node

Right a t r ium

Atrio-ventricularnode

Chordae tend inae

Right ventric le

2





Section-A

1. It is a ta xonomic aid w hich gives a comprehensive account of th e complete compilation of ava ilableinformat ion of an y one taxon at a given time. 1

2. Since urochordat es have a t unic of tunicin, they a re called tunicat es. 1

3. I t i s the deposit ion of wa ter impermeable, wa xy ma ter ia l , suberin on th e ta ngent ia l a nd r adia l

w a lls of th e endoderma l cells of roots. 1

4. It is becau se their fun ctioning cann ot be contr olled by our w ill. 1

5. It is a membrane protein wh ich ena bles glucose tra nsport int o cells. 1

Section-B

6. The sti l t roots ar e advent it ious roots w hich ar ise in clusters from the basa l nodes just a bove the

ground providing support to the plan ts. Exa mples – maize and suga rcan ce. 2

7. Those glan ds w hich ha ve ducts to pour t heir secretion into the respective site of a ction a re calledexocrine gla nds. E xam ples –

(i) salivary glan ds secrete saliva int o the buccal cav ity; a nd

(ii) liver secretes bile int o duodenu m. 2

8. Karyokinesis Cytokinesis

(i) I t is t h e pr oces s of d iv is ion of nu cle us. I t is t h e pr ocess of d iv is ion of cy t opla s m.

(i i) I t corresponds to the separa t ion of the daugh- It corresponds to the separa t ion of the two

ter chromosomes in to two daughter nuclei . daughter nuclei in to two daughter ce ll s.

2

9. It refers to th e volume of filtr a te formed by t he kidneys per m inut e. It is a bout 125 ml/min or 180

litr es/da y. 2

OR

False fruit is a fruit formed from a part of a flower other than the carpels. It is also called

pseudocarp. Exam ple – the stra w berry . 2

10. Ligh t is perceived by th e photopigment s in th e receptors. Ligh t indu ced dissociation of iodopsin

in the cone cells changes the structure of opsin. The potential differences are caused in the

photoreceptor cells. This produces a signal t ha t gen erat es action potential in t he ga nglion cells

thr ough bipolar cells . They a re tr an smitted t o the optic nerves to the visua l cortex of the bra in

an d ima ge formed is recognized. 2

Section-C

11. The non-protein moiety of a conjuga te enzym e is called a cofa ctor. It m ak es the protein cata lyticallyactive. It is are of th ree types na mely, prosthetic group, coenzyme and m etal ions. (Any t wo) 3

12. It is the process in w hich one molecule of glucose is broken down int o tw o molecules of pyruv ic

acid. G lucose an d fructose enter th e glycolyt ic pat hw ay . 3

13. It is a patch of specialized car diac muscles. It is locat ed on t he right upper corner of right a tr ium.

It is responsible for initiat ing an d ma inta ining the rat e of hear t bea t . It is a lso known as pa ce

maker of the hear t . 3

14. For a ny chemical rea ction to ta ke pla ce, a new bond must form. The energy needed to break t he

old bond is called the a ctivation energy . Man y rea ctan ts need a lar ge amount of energy to push




them to take part in a reaction. In the presence of enzymes, the activation energy is greatly

low ered allowing the rea ction t o ta ke place at low t empera tur e. The ha lfwa y point in a reaction

is called the tra nsition sta te. The tra nsition sta te represents th e stage w hen the new bonds ar e

formed. Enzy mes lowers the a ctivation energy by ma king i t easier to achieve the tra nsition sta te.

3

15. Gram-negative Gram-positive

(i) Cell w a ll is 20-80 nm t h ick. Cell w a ll is 8-12 mm th ick.(ii) I t in clu d es few pa t h og en ic b a ct er ia . I t in clu d es mos t of t h e pa t h og en ic b a ct er ia .

(iii) Mesosomes a re prominent . Mesosomes a re less prominent .

(iv) H a ve sin gle-la yer ed w a ll. H a ve dou ble-la yer ed w a ll.

(v) Out er membra n e is a bsent . Out er membra n e is present .

(v i) The bac ter i a remain coloured b lue or The bacter ia do not ret a in st a in when washed

pu rple w it h gr a m st a in in g ev en a ft er w it h alcoh ol.

w ashin g with a lcohol.

3

16. In an nelids, th e body is composed of many segments w hich ar e not by t hemselves reproductively

competent. Su ch structures as nephridia a nd seta e do occur, but ma ny other stru ctures extendthr ough the entire body of the worm a nd do not exist a s sepa ra te structur es in each segment.

Some exa mples ar e the circulatory system a nd th e reproductive system.

In ta pew orm, each of the segments is identica l , differing only in size. Ea ch segment is derived

from th e head. The older segments a re pushed back by new segments. 3

17. The un iversal rules of nomenclatu re a re :

(i ) Biological names are normal ly in La t in an d wri t ten in I ta l ics. They are la t inised or derived

from La tin irrespective of t heir origin.

(i i) First w ord in a biological name represents genus w hile the second na me denotes species.

(i ii ) Both t he words when w ri t ten in han ds are separ ately underlined or pr inted in I ta l ics to

indicat e their La tin origin.

(iv) Firs t word s ta r ts w i th capita l let ter whi le the second word s tar t s wi th sma l l let ter . e.g.,

Tamar ind us indi ca.

(v) Name of the author is wri t ten in abbreviat ion a f ter species name in Roman . e.g., Homo

sapiens (Linn ). 3

18. Some carr ier or t ra nsport proteins al low d iffusion only i f tw o types of molecules move together.

When t he tr an sported molecule an d th e co-tr an sported molecule move in th e same direction, th e

process is called symport. When the two molecules move across the membrane in opposite

directions, t he process is called a ntiport. When a molecule moves across a membra ne independent

of oth er molecules, th e process is called un iport . 3

19. Night blindness is a vita min A deficiency cha ra cterized by poor vision in dim light . It occurs due

to lack of rhodopsin in th e rod cells of th e retina . It ca n be remedied by ha ving food ma ter ials rich

in vitam in A like car rot, papay a et c. 3

OR

The B run ner’s gla nd secretes mucoid fluid. It h as the following char a cteristics :

(i) It is viscous an d enz ym e-free.

(ii) It is a lkaline.

It enables duodenum to with stan d th e acid chyme an d protects i ts wa ll from getting digested.3




20. Heart wood Sap wood

(i) I t i s the centra l, dark coloured non-funct- I t is the peripheral , l ight coloured funct ional

iona l par t o f seconda ry xy lem of an o ld par t of secondary xy lem of an old s tem.

stem.

(ii) I t is hea vier a nd more dura ble. I t is ligh ter a nd less dura ble.

(iii) I t ha s dea d pa ren ch yma tou s cell. I t h as livin g pa ren ch yma tous cell.

(iv) I t does not conduct w ater but gives mech- It helps in conduct ion of wa ter and minerals.an ical to th e stem.

3

21. (a) Ma rg ina l pla centa tion (b) Axile placenta tion (c) P ar ieta l placent a tion (d) Fr ee centra l

placenta tion a nd (e) B asa l placentat ion.

P lacenta is a t issue w ithin the ovar y bearing the ovules. Mustard – parieta l placenta tion a nd P ea

– Mar ginal 3

22. Musta rd shows r aceme inflorescence in w hich the oldest bisexua l flow ers w ith longest pedicel

remain a t the base and young bisexual f lowers wi th short pedicel remain near the t ip of

inflorescence axis. Banana shows spadix inflorescence in which the spike with fleshy axis is

enclosed by one or more lar ge spat he. 3

23. (i ) A good, regular exercise keep diabetes under check.

(i i) Exercise is also crucial to those wh o ar e obese or overweight .

(i i i) Weight t ra ining exercises increases upta ke of calcium in th e bones and help in preventing

osteoporosis (Bone disease).

(iv) Regular exercise also reduces bad cholesterol in our body a nd h elps in improving the fun ction

of the hear t .

Associated value :The learn ers w ill be motiva ted to ta ke up sports activit ies more regula rly t o

keep th em hea lthy. 4

Section-D

24. P lastids a re double membra ne bound orga nelles of different sha pes th at ar e found only in plantcells and conta in pigments a nd st orage products. They a re classified into thr ee types namely :

(i) Leucoplasts – These are oval, spherical, rod-like colourless plastids which are found in

storage orga ns. Their ma in function is to store reserve materials l ike star ch, proteins a nd

fa t s .

(ii) Chromoplasts – These ar e coloured plastids containing yellow, red a nd ora nge pigments

(carotene a nd xant hophy ll). These are found in petals of flowers an d skin of fruits. They

at tra ct ag ents for poll ina tion an d dispersal of fruits /seeds.

(iii) Chloroplasts – These are green pla stids cont a ining ma inly chlorophylls an d little car otene

an d xa nt hophy lls. Their ma in function is photosynt hesis an d forma tion of sta rch. 5

OR

There ar e three stag es namely :

(i) G1 phase – It corresponds to the int erval betw een mitosis an d initia tion of replication of

DNA. There is more synt hesis of RNAs a nd proteins w hich ar e needed for cell growth an d

DNA replica tion.

(ii) S phase– It is th e period dur ing w hich DNA replica tion ta kes pla ce. The a mount of nucleic

acid doubles. In an imal cells , the centr iole start s i ts duplicat ion in th e cytoplasm.

(iii) G2 phase– It is the pha se betw een t he duplicat ion of DNA an d th e beginning of mitosis

pha se. Du ring t his phase more RNAs a nd proteins ar e synthesized for mitosis. 5




25. Nitrogen fixat ion is the process by w hich at mospheric free nitrogen is converted int o amm onia

an d other nitrogen compounds th at ca n be used by plan ts.

At mospheric N2

Biological

N2 fixation

Industrial

N2 fixation

Electrical

N2 fixation Denitrification

(Ammonification) (Uptake)

Decaying biomass Pla nt biomass

Anima l biomass

NH 3 NO2 NO3

5

OR

Chemiosmotic Hypothesis :

(i ) I t wa s put forwar d to explain t he mechanism of ATP synthesis . ATP synthesis i s l inked to

the development of a proton gra dient a cross the membra nes of th ylakoids.

(i i) When electrons ar e t ra nsported th rough ETS, t he protons get accumulat ed inside the

thy lakoids membra ne. These protons a re passed across the membran e into stroma beca use

protons a re removed from t he stroma for t wo rea sons.

(i i i) Firstly t he primary electron a cceptor is located tow ar ds the outside of the membran e andtra nsfers i ts electrons to the H carrier. S o this molecule removes a proton from th e stroma

wh ile tra nsporting a n electron a nd releasing i t into th e lumen or inner side of the membrane.

(iv) Secondly, t he enzyme NADP -reductase is located on t he stroma a long w ith th e electron from

P SI need to be reduced to NADP . Thus a s a r esult , the protons in th e stroma get d ecreased

creating a proton gra dient a cross the th ylakoids membrane. This gra dient is import an t for

ATP synt hesis because energy is released by th e breakdown of th is gradient.

H+

H+

H+

F 0

Lumen

F1

Stroma

ADPATP syntha se

ATP

H+

Thylakoid

membrane

H+

NADP+

NADPHP hotosystem

I

Cytochromes

b & f

Photosystem

II

Soil ‘N’ Pool




(v) The gra dient gets broken due to the movement of protons a cross the membrane thr ough

tra ns membra ne chan nel of the ATP synt heta se. The other portion of ATP synt heta se ca lled

F1 und ergoes conformat iona l cha nges wit h t he energy provided by t he breakdow n of proton

gra dient a nd synt hesizes ATP molecules. 5

26. Digestion of proteins : It t akes place in th e stoma ch an d small int estine.

In stomach :

(i ) Ga str ic juice contains pepsinogen and pro-rennin.

(i i) These proenzymes are activa ted by HC l acid present in th e gastr ic juice.

(i i i) P epsin a cts on proteins and converts them into proteoses and peptones.

(iv) Rennin hydr olyses milk proteins.

In the intestine :

(i ) The substra tes of enzymes are pancreat ic an d intest inal juices . Pan crea t ic juice conta ins

trypsin, chymotrypsin a nd ca rboxypeptida se.

(i i) Tryps in a c t s on pro teins , pro teoses and peptones conver t ing th em in to d ipept ides .

Chy motrypsin hyd rolyses the milk proteins.

(i i i) Ca rboxypeptidase acts on th e termina l peptide bond a nd releases th e la st am ino acid and

progressively short ens th e peptide cha in.

(iv) Int estinal juice conta ins enterokinase, amino peptidases and dipeptidases. Enterokinase

activa tes the try psinogen into active trypsin.(v) Amino pept idases act on th e terminal pept ide bond a nd release the las t amino acid a nd t hus

shorten t he peptide chain.

(vi) Dipeptida ses act in th e dipeptides and break t hem into individual amin o acids. 5

OR

P y ru v a t e

(3D)

Acetyl coenzyme A(2C)

Citric a c id(6C) C O2

NAD +NAD +

N AD H + H+

N AD H + H +

a -ketoglutaric acid(5C)CITRIC ACID CYCLE

C O2

NAD+

N AD H + H+

ATP

AD PSuccinic acid

(4C)

F AD +

FADH 2

Malic a cid(4C)

Oxaloacetic acid(4C)

5





Section-A

1. It m eans in a n ar ti ficial environment such a s test-tube. 1

2. S a liva ry gla nds, liver a nd ga ll bla dder . (Any t w o) 1

3. (a) Ba nya n t ree – P rop trees, (b) Ma ngrove trees – P neuma tophores. 1

4. The protein component of silk fibre derived from silkworms and spiders which form threads to

creat e webs an d cocoons. 1

5. (a) No. of chromosomes does not chan ge in a ny sta ge of cell cycle during mitosis and in meiosis,

i t changes to hal f in ana phase I . ½

(b) S-pha se of interpha se – The DNA content doubles aft er DNA replication. ½

Section-B

6. The movement of w at er occurs exclusively t hrough th e cell wa ll an d inter cellular spaces.

It does not cross an y membra ne or living component of the cell. It occurs in cortex as t he cortica lcells a re loosely arr an ged a nd offer no resista nce. Since endodermis ha s casparia n strips made of

suberin, i t does not a l low movement to pass th rough a nd so the w at er is forced to follow symplast

pa thway . 2

OR

Fibrous joints do not allow any movement. This type of joint is shown by the flat skull bones

w hich fuse end-to-end w ith t he help of dense fibrous conn ective tissues in t he form of sutur es, to

form the cra nium. In carti laginous joints, t he bones involved a re joined together w ith t he help of

cart i lages. The joint betw een t he ad jacent vert ebrae in the vert ebra l column is of this patt ern

an d i t permits l imited movement s. 2

7. (i) B y direct tra nsfer of phosphat e to ADP .

(ii) B y oxida tion of NADH pr oduced in glycolysis t o NAD in E TS. 28. The malphighia n tu bules ar e found a t th e junction betw een midgut a nd h indgut in insects l ike

cockroach, grasshopper etc. it helps in excretion. Gizzard is found in the digestive system of

ear thw orm, cockroach an d birds. It helps in grinding th e food materia ls. 2

9. Coeloptile is th e leaf l ike sheat h t ha t covers a nd protects the plumule. Coleorrhiza is th e sheath

tha t protects th e radicle. 2

10. The four classes of kingdom fungi are : Phycomycetes, Ascomycetes, Basidiomycetes and

Deuteromycetes. 2

Section-C

11. Cla ss I – Oxidoreducta ses, Class II – Tra nsferases, Cla ss III – Hyd rolases, Class I V – Lya ses,

Cla ss V – Isomera ses a nd Cla ss VI – Ligases. 3

12. Xylem an d phloem a re called complex tissues as th ey ar e mad e up of more th an one type of cells

and they work as a uni t .

Xylem components are :

(i ) Tra cheids ar e elongat ed or tube l ike cells wi th thick an d l ignif ied wa l ls an d ta pering ends .

These are dead a nd a re with out protopla sm.

(ii) Vessel is a long cylindr ical t ube-like structure m ade up of many cells called vessel members,

each wi th l igni f ied wa l ls and a large centra l cavi ty .

(i i i) Xylem fibres ha ve highly thickened w alls and oblitera ted centr al lumens. These ma y either

be septat e or asepta te.




(iv) Xylem parenchyma cel ls ar e l iv ing an d th in-wa l led and their cell wa l ls ar e made up of

cellulose.

Phloem components are :(i) Sieve tube elements are long, tube-like structures, arra nged longitudinally and a re associated

wit h t he compan ion cells. Their end wa lls a re perforated in a sieve-like ma nner to form the

sieve plat es.

(i i) Companion cells are specialised parenchym at ous cells, wh ich a re closely associa ted with

sieve tu be element s.

(i i i) P hloem parenchyma is ma de up of elongat ed, tapering cylindrical cells which ha ve densecytoplasm a nd n ucleus.

(iv) P hloem fibres are mad e up of sclerenchyma tous cells. 313. Actinomorphic :Such flowers show ra dial symmetry a nd can be divided into tw o similar ha lves

in a ny ra dia l plan e passing t hrough the center , e.g. Mus tard .

Zygomorphic : (B ilatera l symmetrical) They can be divided into tw o similar ha lves only in one

part icular plane, e.g. Sw eet pea, B ean.

Asymmetric : (Ir regular) Ca nnot be divided into tw o similar ha lves in a ny plan e, e.g. C a n n a . 3

14. P hyllota xy refers to the mode of arra ngement of lea ves on stem or bran ch.

Racemose inflorescence Cymose inflorescence

(i)F low er openin g is cent r ipet a l. F low er opening is cen t r ifuga l.

(ii) Th e t er min a l bu d con tin ues t o g row . Th e t er min a l bu d for ms a flow er .(iii) Flowers are arra nged in an a cropetal order . Flowers are arra nged in a basipetal order .

315. Rad ial symmetry: E chinoderma ta , Ha emocoel : Art hropoda, Water va scular system :

Echinodermata , Setae : Annel ida , P neumatic bones : Chordata and R adula : Mollusca . 3

16.

Lipid bilayer

ProteinSugar

Cholesterol

3

OR

3




17. (a) Gibber ellins, (b) Cy tokinin s, (c) Auxin . 3

18. P lant s ar e grouped into the follow ing th ree cat egories :

(a) Short-day plants – These plan ts w hich need a light short er th an th eir critical photoperiods

for flow ering. e.g., – Chry san themum, Cosmos.

(b) Long-day plants – These plants which need l ight period longer than their cr i t ica l

photoperiods for flow ering . e.g., – Wheat , bar ley.

(c) Intermediate-day plants – These plan ts a re not influenced by lengt h of ligh t period for

flowering. e.g., – Tomat o, cucumber. 3

19. C OOH C OOH C OOH

H H H

H

C C CNH 2 NH 2 NH 2

C H 3 C H 2—O H

G lycin e Ala nine S er in e

3

20. Ant erior a orta

Alary muscles

Chambers

of heart

3

21.

Outermembrane Inner

membrane

Inner-membranespace

Matrix

Cristal

3

22.

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

Va lva t e Tw is ted I mbr ica t e Vexilla r y 3

23. Katrina could have brought only one full plant to demonstrate instead of uprooting so many

sapl ings . This prac t i ce shows i r respons ib le and indi f ferent a t t i tude o f Ka t r ina towards

environment.

Value – Responsibili ty, ca re, concern a nd respect for na tur e. 3+1=4




Section-D

24. (1) Most of t he w at er flow in th e roots occurs via the a poplast since the cortical cells ar e loosely

packed, and h ence offer no resistan ce to wa ter movement . However, the inner bounda ry of

the cort ex, the endodermis, is impervious to wa ter because of a ba nd of suberized ma tr ix

called the caspar ian str ip.

(2) Wat er molecules a re unable to penetra te the layer, so th ey are directed to wa ll regions th at

ar e not suberised, int o the cells proper t hrough t he membran es.

(3) The wa ter th en moves thr ough the symplast an d ag ain crosses a m embrane to reach t he cells

of the xylem. The movement of w at er th rough th e root lay ers is ultimately symplast ic in th e

endodermis. This is the only wa y w at er an d other solutes can enter th e vascular cylinder.

Once inside the xylem, wa ter is aga in free to move between cells as w ell as t hrough t hem.

(4) In young roots, w at er enters directly into the xylem vessels an d/or tra cheids. These are non-

living conduits a nd so ar e parts of the a popla st . 3

Endodermis Xylem

P ericycle

Caspar ian

stripCortexApoplastic

pa th

Symplast ic

pa th

Phloem

2

OR

(1) Whenever the supply of an essential element becomes l imited, pla nt gr owth is reta rded.

(2) The concentrat ion of the essentia l element below w hich plant growth is retar ded is termed a s

deficiency. The element is said t o be deficient w hen present below t he critical concent ra tion.

Since each element h as one or more specific stru ctura l or functiona l role in plants , in th eabsence of a ny pa rticular element, plants sh ow certain morphological cha nges.

(3) These morphologica l chang es a re indicative of certa in element deficiencies a nd a re called

deficiency symptoms. The deficiency symptoms vary from element to element and they

disappear w hen th e deficient mineral nut rient is provided to the plant .

(4) However, i f deprivat ion continues, i t may eventua lly lead t o the deat h of the plant . The part s

of the plant s tha t show th e deficiency symptoms also depend on th e mobili ty of the element

in the plant. For elements that are actively mobilized within the plants and exported to

young developing t issues, th e deficiency symptoms t end t o appear first in t he older t issues.

For example, the deficiency symptoms of nitrogen, pota ssium a nd m agn esium a re visible

first in t he senescent leav es.

(5) In the older leaves, biomolecules conta ining th ese elements a re broken down , ma king th ese

element s ava ilable for mobilising t o youn ger leaves. The deficiency sympt oms tend t o appearf i rs t in the young t issues whenever the elements are rela t ively immobi le and are not

tra nsported out of the ma tur e orga ns, for exa mple, elements l ike sulphur a nd ca lcium ar e a

par t of the structu ra l component of th e cell an d hence are not ea sily released.

(6) The kind of deficiency symptoms shown in plant s includes chlorosis, necrosis, and stunt ed

plant growt h, prematu re fal l of lea ves an d buds, a nd inhibition of cell division. Chlorosis is

th e loss of chlorophyll lead ing t o yellow ing in leaves. This sym ptom is cau sed by t he deficiency

of elements N, K, Mg, S, F e, Mn, Zn an d Mo. Likew ise, necrosis, or deat h of tissue, pa rticularly

lea f t issue, is due to the deficiency of Ca, Mg , Cu a nd K . La ck or low level of N, K, S an d Mo

cau ses an in hibition of cell division. Some element s like N, S a nd Mo delay f lowering if th eir

concentra tion in plan ts is low. 5




25. (1) The most exciting a spect of chemistry deals w ith isolat ing th ousands of compounds fr om

living orga nisms, determining t heir stru cture an d synt hesizing them. These orga nic compounds

including a mino acids, sugar s, etc. ar e called ‘metabolites’. I n a nima l t issues, the presence of

a ll such cat egories of compounds is called prima ry m eta bolites.

(2) How ever, w hen one ana lyses plant , funga l and m icrobial cells , one would see thousands of

compound s other tha n t hese called primar y meta bolites, e.g. alkaloids, flavonoides, rubber,

essential oils, antibiotics, coloured pigments, scents, gums and spices. These are called

secondar y meta bolites.

(3) The primary meta bol i tes ha ve ident i f iable funct ions an d play kn own roles in normal

physiological processes. It is easy t o understa nd t he role or fun ctions of al l the ‘secondar y

meta bolites’ in h ost organ isms. However, man y of them a re useful to ‘human welfar e’ (e.g.,

rubber, drugs, spices, scents and pigments). Some secondary metabolites have ecological

importance.

Some Secondary Metabolites

Carotenoids, Anthocyanins,

etc.

Merphine, Codeine, etc

Monoterpenes, Diterpenes etc.

Lemon gra ss oil, etc.

Abrin, Ricin

Concanaval in AVinblastin , curcumin. etc.

Rubber. gums, cellulose

P igments

Alkaloids

Terpenoides

Essential oils

Toxins

LectinsDrugs

Polymericsubstances

5

OR

(1) Electron microscopic stud ies of eukar yotic cells reveal th e presence of a n etw ork or ret iculum

of t iny tubular structur es scat tered in the cytoplasm t ha t is called t he endoplasmic reticulum

(ER). Hence, ER divides the intra cellular space int o two distinct compar tment s, i.e., lumina l

(inside ER) and extra lumina l (cytoplasm) compar tment s.

(2) The ER often shows r ibosomes at ta ched to their outer su rface. The endoplasm ic reticulum

bear ing ribosomes on t heir sur fa ce is ca lled rough endoplasmic reticulum (RER ). In t he a bsence

of ribosomes th ey a ppear smooth an d a re called smooth endoplasmic reticulum (SER).

(3) RER is frequent ly observed in the cells actively involved in protein synt hesis and secretion.They a re extensive and cont inuous with the outer membrane of the nucleus. The smooth

endoplasmic reticulum is th e major site for sy nt hesis of lipid. I n a nima l cells, lipid like steroidal

hormones ar e synthesized in SE R. 3

Nucleus

Nuclear poreRough

endoplasmicreticulum

Ribosome

SmoothEndoplasmic

reticculum

2

26. (1) Andr oecium is composed of sta mens. Ea ch stamen wh ich represents th e male reproductive

organ consists of a sta lk or a fi lament a nd a n an ther. E ach a nth er is usua lly bilobed and ea ch




lobe has two chambers, the pollen-sacs. The pollen grains are produced in pollen-sacs. A

sterile stamen is called staminode. Stamens of flower may be united with other members

such as peta ls or a mong themselves.

(2) When sta mens are a tta ched to th e peta ls, they ar e epipetalous as in brinja l , or epiphyllous

wh en at ta ched to the periant h a s in the flowers of l ily. The sta mens in a flower ma y either

rema in free (polyan drous) or ma y be united in va rying d egrees. The sta mens ma y be united

into one bunch or one bundle (monoa delphous) a s in china rose, or tw o bundles (diad elphous)

a s in pea, or into more tha n t w o bundles (polya delphous) as in citru s. There ma y be a va ria tion

in the length of f i laments w i thin a f lower , as in Salvia an d musta rd.

(3) G yn oecium is the female reproductive part of the flower a nd is ma de up of one or more

carpels. A carpel consists of three part s na mely stigma , style and ovary. Ova ry is the enlarged

basa l part , on wh ich l ies th e elongat ed tube, the sty le. The style conn ects t he ovary to the

stigma . The stigma is usually a t the t ip of th e style an d is the r eceptive surfa ce for pollen

gra ins. Ea ch ovar y bear s one or more ovules at ta ched to a flat tened, cushion-like placent a.

(4) When more tha n one car pel is present , they ma y be free (as in lotus an d rose) an d ar e called

apocarpous. They ar e termed synca rpous wh en ca rpels ar e fused, as in musta rd a nd toma to.

After ferti l isation, the ovules develop into seeds an d t he ovary mat ures into a fruit . 5

OR

(1) All the four chambers of hear t are in a relaxed s ta t e , i .e . , they ar e in joint diastole. As th e

tricuspid an d bicuspid va lves are open, blood from the pulmonary veins and vena ca va flow sinto the left and t he right ventr icle respectively through the left and right a tr ia.

(2) The semilunar valves are closed at t his stage. The SAN now genera tes an a ction potent ial

wh ich stimulat es both the at ria t o underg o a simulta neous contr a ction – the atr ial systole.

This increa ses the flow of blood int o the v entr icles by a bout 30 per cent.

(3) The a ction potential is conducted to the ventricular side by the AVN a nd AV bundle from

wh ere the bundle of His tr an smits it t hrough t he entire ventricular musculat ure. This causes

the ventricular muscles to contract , (ventricular systole), the atria undergoes relaxation

(dia stole), coinciding wit h th e vent ricular sy stole.

(4) Ventricular syst ole increases the ventr icular pressure cau sing th e closure of tricuspid a nd

bicuspid va lves due to at tempted ba ckflow of blood int o the at ria . As th e vent ricular pr essure

increases furth er, the semilunar va lves gua rding th e pulmona ry a rtery (right side) an d the

aort a (left side) are forced open, al lowing t he blood in t he ventr icles t o flow t hrough th esevessels into th e circulatory pa thw a ys. The ventricles now r elax (ventricular diastole) and the

ventricular pressure falls causing t he closure of semiluna r va lves which prevents t he ba ckflow

of blood into the ventricles. As the ventricular pressure declines further, the tricuspid and

bicuspid va lves a re pushed open by t he pressure in th e atr ia exerted by th e blood w hich wa s

being emptied into th em by t he veins. The blood n ow once ag ain moves freely to t he vent ricles.

(5) The ventricles and a tr ia ar e now aga in in a relaxed (joint dia stole) sta te, as ear lier. Soon the

SAN genera tes a n ew a ction potential an d the events described a bove are repeated in tha t

sequence and the process continu es. This sequentia l event in t he hea rt wh ich is cyclically

repea ted is called th e cardiac cycle a nd i t consists of systole and d iastole of both the a tria an d

vent ricles. The hea rt bea ts 72 times per minut e, i .e . , tha t ma ny car diac cycles ar e performed

per minute.

(6) The body ha s the a bil ity to a l ter the s troke volume as w ell as the heart ra t e and t hereby th e

cardiac output. F or example, the cardiac output of an a thlete will be much higher t ha n tha t of

an ordina ry ma n. D uring each cardia c cycle two prominent sounds a re produced w hich can be

easily hear d t hrough a stethoscope. The first h eart sound (lub) is a ssociat ed w ith t he closure

of the tr icuspid an d bicuspid valves w hereas t he second hear t sound (dub) is associat ed w ith

th e closure of th e semilun a r va lves. These sounds a re of clinical dia gnostic significan ce. 5





Section-A

1. These ar e cells th at l ine the inner cavity of the sponge. 1

2. The lampreys differ from th e fam iliar fishes by the a bsence of ja w s, paired fins a nd presence of

gill pockets in pla ce of gill cover s. 1

3. (a ) Sa rcolemma an d (b) Nerve. 1

4. A stru cture a t t he cent romere to which the spindle fibres ar e at ta ched is called kinetochore. 1

5. The light intensity at wh ich th e ra te of respiration by photosynt hetic cell or orga n equa ls its r at e

of photosyn th esis is called compensa tion point. 1

Section-B

6. (i ) I t ma intains a s trongly ac idic pH of about 1 – 2 in the stomach.

(i i) It converts ina ctive pepsinogen to pepsin.(i i i) It dena tures ma ny food proteins. This helps in pepsin a ction.

(iv) I t ki ll s bacter ia . 2

7. The non-protein moiety of a conjuga te enzym e is called a cofa ctor. It m ak es the protein cata lytically

active. It is a re of three types na mely, prosthetic group, coenzyme a nd meta l ions. (Any t wo) 2

8. Calorific value Physiological value

(i) The value of car bohydrat es , proteins and

fa t s a re 4.1 kcal/g, 5.65 kcal/g a nd 9.45

kca l/g respect ively.

(ii) Th e a m o u n t of h e a t l ib e r a t e d f r o m

complete combust ion of 1g food in a bombcalorimeter is its gr oss ca lorific va lue.

The value of carbohydrates, proteins and fats

a re 4 .0 kca l/g , 4 .0 kca l/g a nd 9 .0 kca l/g

respectively.

The actual amount of energy l iberated in the

hum a n body du e to combust ion of 1g of food isits physiologica l value.

2

9. It is the process in w hich one molecule of glucose is broken down int o tw o molecules of pyruv ic

acid. G lucose an d fructose enter th e glycolyt ic pat hw ay . 2

10. OC H 2

CH 2CH 2

O

O

OO

HOO= P --- OH

OP O

O

Thym ine ::::: ::: Adenine

Guanine :::::::: Cytosine

CH2

O

5' 3'

3'5'

2




OR

Cytokinesis in plant cell Cytokinesis in animal cell

(i) I t occu r s by t h e f or ma t ion of cell pla t e. I t t ak es pla ce by fu rr ow in g or clea va g e.

(ii) Cell pla te gr ow s cent r ifuga lly . C lea va ge prog resses cent r ipet a lly .

(i ii ) Cel l pla te is formed between the new nuclei A cleavage is formed around the middle.

and then expan ds outw ard to jo in wi th th e

old membra nes.2

Section-C

11. Tra nspiration is the loss of surplus wa ter in th e form of wa ter va pours from the a erial surfa ce of

plants .

G utt at ion is the loss of wa ter in the form of w at er droplets.

G utt at ion ta kes place from veinal ends called hyda thodes. 3

12.

1 2

3 4 5 6 7 8 9 10 11 12 13 14 15 16

Lateraloesophageal

heartsCommissural

vessel

SubneuralvesselAnterior

loopsVentralvessel

Lat eral oesphagealvessel

Dorsal vessel Lateral hearts

3

13.Root hair

Epidermis

Cortex

Endodermis

Pericycle

Protoxylem

Metaxylem

Pith

Phloem

T.S. of Dicot Root 3




18. Night blindness is a vita min A deficiency cha ra cterized by poor vision in dim light . It occurs due

to lack of rhodopsin in th e rod cells of th e retina . It ca n be remedied by ha ving food ma ter ials rich

in vitam in A like car rot, papay a et c. 3

OR

The B run ner’s gla nd secretes mucoid fluid. It h as the following char a cteristics :

(i ) I t i s v iscous and enzyme-free .

(ii) I t i s a lka li n e.

It enables duodenum to with stan d th e acid chyme an d protects i ts wa ll from getting digested.3

19. The va rious fun ctions of epithelial tissues a re :

(a) Protection – The epithelial tissue protects the underlying tissue from injury, chemicals,

bacteria etc.

(b) Sensation– The specia lized epithelia l tissue consisting of sensory nerve end ings a re found

in the skin, eyes, nose, ea rs an d the t ongue.

(c) Secretion – The epithelial t issue secretes definite chemical subst an ces such as enzy mes,

hormones a nd lubricating fluids.

(d) Absorption – The epith elial t issue l ining the sma ll intestine a bsorb nu trients from the

digestion of food.

(e) Excretion – The epithelial t issue in kidney excretes wa ste products from t he body an d

reabsorbs needed mat erials from the urine.

(f) Diffusion – S imple epithelium helps in diffusing ga ses, l iquids, nut rients etc.

(g) Transportation – Ciliat ed epith elium h elps to remove dust par ticles and foreign bodies. 3

20. Rods Cones

(i) Th e se a r e m ea n t f or v is ion i n d im lig h t . Th e se a r e me a n t for vi si on in b r ig h t lig h t .

(i i) They do not have the abi li ty to make They have the abi li ty to make coloured image.

coloured ima ge.

(i i i) These contain th e visual pigment rhodopsin. These conta in t he pigment iodopsin.

(Any th ree) 3

21. Cyclic photophosphorylation Non-cyclic photophosphorylation

(i ) The elect rons emi t ted by PSI come back The elec t rons emit ted by P SI I do not come

t osa me P SI ch lor ophy ll. ba ck to sa me P S I I .

(ii) I t involves P S I . I t involves P S I I .

(iii) I t forms 2 ATP molecules. I t forms one ATP molecules.

(iv ) N o ph ot oly sis or NAD P H occu rs. Th er e is ph ot oly sis of w a t er a nd pr od uct ion of

NADPH.

(v) Oxy gen is not libera t ed. Oxy gen is libera t ed.

3

22.Par ie t a l

Occipital

Fronta l

Sphenoid

Zygomat ic

Mandible

3




23. (i) No.

(i i) Int ake of such conta mina ted milk may cause var ious healt h disorders.

Associated value : The learn ers w ill become more vigilan t w hile ta king milk or milk products

an d w ould prefer t o ta ke them from registered outlet l ike Mother Dia ry, D MS etc. 3+1=4

Section-D

24. P lastids a re double membra ne bound orga nelles of different sha pes th at ar e found only in plant

cells and conta in pigments a nd st orage products. They a re classified into thr ee types namely :

(i) Leucoplasts – These ar e ova l, spherical, rod-like colourless plast ids w hich a re found in

storage orga ns. Their ma in function is to store reserve materials l ike star ch, proteins a nd

fa t s .

(ii) Chromoplasts – These ar e coloured plastids containing yellow, red a nd ora nge pigments

(carotene a nd xant hophy ll). These are found in petals of flowers an d skin of fruits. They

at tra ct a gents for pollina tion an d d ispersal of fruits/seeds.

(iii) Chloroplasts– These are green pla stids cont a ining ma inly chlorophylls an d little car otene

an d xa nt hophy lls. Their ma in function is photosynt hesis an d forma tion of sta rch. 5

OR

Early Prophase Lat e P rophase

Tra nsition to

Metaphase

Meta pha se Ana pha se Teloph a se I nt er ph a se

5

25. (1) P ectoral a nd P elvic girdle bones help in t he a rticulation of the u pper a nd t he low er l imbsrespectively with the a xial skeleton. E ach girdle is formed of tw o ha lves. Ea ch ha lf of pectoral

girdle consists of a clavicle an d a scapula .

(2) Scapula is a larg e t r iangular f la t bone s i tuated in the dorsal par t of the thorax between the

second a nd th e seventh ribs. The dorsal, flat, tr ian gula r body of sca pula ha s a slightly elevat ed

ridge called t he spine wh ich projects a s a flat , expanded process called t he a cromion.

(3) The cla vicle ar ticulat es with t his. B elow t he a cromion is a depression ca lled th e glenoid cavity

w hich ar ticulat es with the hea d of the humerus to form the shoulder joint. E ach clavicle is a

long slend er bone with tw o curva tu res. This bone is commonly ca lled the collar bone.




(4) P elvic gird le consists of tw o coxal bones. Ea ch coxa l bone is formed by th e fusion of th ree

bones – ilium, ischium a nd pubis. At t he point of fusion of th e above bones is a ca vity ca lled

acetabulum to which the thigh bone articulates. The two halves of the pelvic girdle meet

ventra lly to form t he pubic symphysis cont ain ing fibrous cart i la ge.

Elium

Punis

Clavicle

Scapula

Humerus

Radius

Uina

Carpals

Metacarpals

Phalanges

Ischium

Coxal bone

Sacrum

Femur

Patella

Tibia

Fibula

Tarsals

Metatarsals

Phalanges5

OR

Tra nspiration ha s more tha n one purpose such a s :

(i ) I t creat es t ra nspirat ion pull for absorpt ion and t ra nsport of plants .

(i i) I t supplies wa ter for photosynthesis.

(i i i) It t ra nsports minerals from the soil to a l l par ts of th e plant .

(iv) It cools leaf sur faces, sometimes 10 to 15 degr ees, by eva pora tive cooling.

(v) I t ma intains the shape and s tructure of the plant s by keeping cel ls turgid.

An a ctively photosynt hesizing plan t h as a n insat iable need for wa ter. P hotosynthesis is l imited

by ava ilable wa ter w hich ca n be swift ly depleted by tra nspirat ion. The humidity of ra in forests is

lar gely du e to this va st cycling of wa ter from root t o leaf t o atm osphere an d back to the soil. The

evolution of the C 4 photosynthetic system is proba bly one of th e stra tegies for ma ximising t he

ava ilabil i ty of CO 2 wh ile minimising w a ter loss. C4 plants a re tw ice as efficient a s C 3 plants in

terms of fixing carbon (ma king suga r). However, a C 4 pla nt loses only ha lf as much wa ter as a C 3

plan t for the same a mount of CO2 fixed. 5

26. P roteins are polypeptides. They a re l inear cha ins of amino a cids l inked by peptide bonds. Ea ch

protein is a polymer of a mino a cids. As th ere ar e 21 ty pes of am ino acids (e.g., ala nine, cysteine,

proline, tryptophan, lysine, etc.), a protein is a heteropolymer and not a homopolymer. Ahomopolymer ha s only one type of monomer repeating ‘n’ number of t imes. Certa in a mino acids

ar e essential for our h ealth a nd t hey ha ve to be supplied t hrough our diet . Hence, dietary proteins

a re th e source of essentia l amin o acids. Therefore, a mino acids can be essentia l or n on-essentia l.

The latt er are th ose wh ich our body can ma ke, while we get essential a mino acids thr ough our

diet/food. P roteins carry out ma ny fun ctions in living orga nisms, some tra nsport nu tr ients a cross

cell membrane, some fight infectious organisms, some are hormones, some are enzymes, etc.

Collag en is the most a bunda nt protein in an imal world a nd Ribulose bisphosphat e Car boxylase-

Oxygena se (RU B ISC O) is the most abund an t protein in t he wh ole of the biosphere.




Some Proteins and their

Functions

Protein

Collagen

Trypsin

InsulinAntibody

Receptor

G LU T -4

Functions

Intercellular ground

substance

Enzyme

HormoneFight infectious agents

Sensory reception

(sma ll, ta ste, hormone,

etc.)

Ena ble glucose

transport

into cells 5

OR

Calvin a nd his co-workers then w orked out t he wh ole pathw ay and showed tha t the pat hw ay

operated in a cycl ic manner ; the RuB P wa s regenerated. Let us now see how the Ca lvin pat hwa y

operates an d w here the sugar is synthesised. Let us a t the outset understan d very c lear ly tha tthe Ca lvin pa thw ay occurs in a l l photosynthet ic plants ; i t does not m at t er wh ether they h ave C 3or C 4 (or any other) pat hw a ys. There ar e three sta ges in Ca lvin cycle: ca rboxylat ion, r eduction

an d regenerat ion.

(1) Carboxylation – Ca rboxyla tion is th e fixat ion of CO2 into a stable organic intermediate.

Ca rboxylat ion is th e most crucial step of th e Ca lvin cycle where CO2 is utilised for th e ca rboxylat ion

of RuBP . This reaction is ca ta lysed by th e enzyme RuBP carboxylase wh ich results in the format ion

of two molecules of 3-P G A. Since th is enzym e also ha s a n oxygena tion activity i t w ould be more

correct t o call i t RuB P carboxylase-oxygena se or Ru B isCO.

(2) Reduction – These a re a ser ies of rea ctions th at lead t o the forma tion of glucose. The st eps

involve utilisat ion of 2 molecules of ATP for phosphory lat ion an d tw o of NADP H f or reduction

per CO2 molecule fixed. The fixa tion of six molecules of CO 2 an d 6 turns of the cycle are required

for the remova l of one molecule of glucose from the pa th w ay .(3) Regeneration – Regenera tion of the CO2 acceptor molecule RuB P is crucial if the cycle is to

continue uninterrupted. The regeneration steps require one ATP for phosphorylation to form

R u B P .

Hence for every CO 2 molecule entering th e Ca lvin cycle, 3 molecules of ATP a nd 2 of NAD P H a re

required. It is probably to meet this difference in number of ATP an d NADPH used in th e dar k

rea ction tha t t he cyclic phosphorylat ion ta kes pla ce.

In

Six CO

18 ATP

12 NADP H

2 One glucose

18 ADP

12 NADP

Out

5

o1384244546tBio Solutions 6-10 XI

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Transcript of o1384244546tBio Solutions 6-10 XI