CBSE Guess Paper: 2011
Class- XII
(Biology-Theory)

Time allowed: 3 hours
Maximum Marks:70
Instructions:
1. Q- 1-8 CARRY 1 MARKS EACH
2. Q- 9-18 CARRY 2 MARKS EACH
3. Q 19-27 CARRY 3 MARKS EACH
4. Q-28-30 CARRY 5 MARKS EACH
5. Alwyas draw neat and labelled digram whetther asked or not
6. Give answer according to marks in order to save time..

SECTION – A

Q.1. HOW THE SENSTIVITY OF THE TECHNIQUE "DNA FINGERPRINTING" CAN BE INCREASED ? (1 Marks)

Q.2. WHY THE PYRAMID OF BIOMASS IN SEA IS GENRALLY INVERTED?(1 Marks)

Q.3. NAME THE FOLLOWING
A. IMMUNOGLOBIN ACTS AS MEDITATOR IN ALLERGIC RESPONSES
B. BIOLOGICAL RESPONSE MODIFIER WHICH HELPS IN DESTROYING TUMOR H (1/2 + 1/2 Marks)

Q.4. DO EUKARYOTIC CELS HAVE RESTRICTION ENDONUCLEASES?.JUSTIFY (1/2 +1/2 Marks)

Q.5. NAME THE IMPROVED VARIETY OF RAPESEED MUSTARD THAT IS RESISTANT TO APHIDS. (1 Marks)

Q.6. STATE GAUSE'S COMPETITION EXCLUSION PRINCIPLE. (1 Marks)

Q.7. NAME ONE KEY CONCEPT OF DRAWINAIN THEORY OF EVOLUTION OTHER THAN NATURAL SELECTION. (1 Marks)

Q.8. WHAT ARE SOMACLONES?.(1 Marks)

SECTION -B

Q.9. GIVE THE SEQUENCES OF EVENTS IN"MULTIPLE OVULATION EMBRYO TRANSFER TECHNOLOGY PROGRAMME" FOR INCREASING THE HERD SIZE IN CATTLE (1/2 * 4 =2 Marks)

Q.10. A. WHICH GROWTH MODEL IS CONSIDERED A MORE REALISTIC AND WHY?(1/2 +1/2 Marks)
B. NAME THE FOLLOWING
1. SMALLER BARNACLES IS RESTRICTED BY SUPERIOR BARANACLE.............. (1/2 Marks)
2. WARBLERS LIVING ON SAME TREE CO-EXIST AND DO NOT COMPETE.......... (1/2 Marks)

Q.11 A. WHERE DOES REPLICATION OF EUKARYOTES TAKES PLACE IN CELL CYCLE WHAT WILL BE CONSEQUENCES IF THERE IS FAILURE OF CELL DIVISION AFETR DNA REPLICATION (1/2 + 1/2 Marks)

B. GIVE ANY ONE REASON WHY BOTH THE STRANDS ARE NOT COPIED DURING TRANSCRIPTION (1 Marks)

Q.12. DEFINE TOTIPOTENCY . WRITE ANY TWO STEPS IN BREEDING A NEW GENETIC VARIETY. (1/2 +1/2 Marks)

OR

A. EXPAND MALT . (1/2 Marks)
B. WHAT IS SIGNIFICANCE OF MALT. (1/2 Marks)
C. NAME THE DIAGNOSTIC TEST FOR AIDS. (1/2 Marks)
D. WHAT IS THE PRINCIPLE OF IMMUNISATION (1/2 Marks)

Q.13 A.EXPAND PAR (1/2 Marks)
B. NAME THE PIONEER SPECIES ORGANIMS ON BARE ROCK. IN WHICH ENVIORMENT DO THEY GROW IN REFRENCETO POLLUTION (1/2 Marks)
C.WHAT IS ROLE OF CFC'C IN OZONE DEPLETION .(1 Marks)

Q.14 A. NAME ANY TWO PARASITIC SPECIES OF FRUIT WHICH CONTAIN LARGE NUMBER OF SEEDS. (1 Marks)
B. HOW POLLEN GARINS CAN BE STORED FOR YEARS. (1/2 Marks)
C. WHAY TAPETUM CELLS HAVE DENSE CYTOPLAMS (1/2 Marks)

Q.15. HOW AND WY IS BACTERIUM THERMUS AQUATICUS EMPLOYED IN RECOMBIANT DNA TECNOLOGY.EXPLAIN. (2 Marks)

Q.16. CITE CASE OF CO-EVOLUTION WITHE THE HELP OF AN EXAMPLE. (2 Marks)

Q.17. A. DRAW WELL LABBELED DIGRAM OF IMMULOGLOBIN ( ANY TWO LABELLING) (1 Marks)
B. HOW IS CANCEROUS CELL DIFFERBT FROM NORMAL CELLS.(1 Marks)

Q.18. A. WHY DISTANCE BETWEEN TWO POLYPEPTIE CHAINS IN DNA REMAINS ALMOST CONSTANT. (1 Marks)
B REPRESENT CENTRAL DOGMA AND WHO PROPOSED IT. (1/2 +1/2 Marks)

SECTION-C

Q.19. STUDY THE FOLLOWING FLOW CHART.NAME THE HORMONES INVOLVED AT EACH STAGE .EXPLAIN THEIR FUNCTIONS
HYPOTHALMUS ------PITUITARY------TESTES-----SPERMS (3 Marks)

Q.20. A. DRAW STRUCTURE OF BACTERIOPHAGE WITH ATLEAST 2 LABELINGS.(1 Marks)
B. WHAT ARE ACTIVATED SLUDGE. (1 Marks)
C. WHAT ARE BACULOVIRUSES . THEY ARE USED AS BIOLOGICAL AGENT IN THE GENUS....... (1/2 +1/2 Marks)

Q.21. A. NAME THE CASE IN WHICH GENOTYPIC AND PHENOTYPIC RATIOS ARE SAME .DEMOSTRATE THE CROSS ?.WRITE THE SCIENTIFIC NAME OF FLOWER . (1/2 + 1 + 1/2 Marks)
B.A DIPLOID ORGANISM IS HETEROZYGOUS FOR 4 LOCI , HOW MANY TYPES OF GAMETES CAN BE PRODUCED?. (1 Marks)

Q.22. IN WHAT REFRENCE FOLLOWING TERMS ARE USE.
A. LUNGS OF PLANET (1 Marks)
B. THE EVIL QUARTET (1 Marks)
C. BIOPROSPECTING (1 Marks)

Q.23. A. WHY IT IS DIFFICULT TO PASS THROUGH CELL MEMBRANES?. HOW BACTERIAL CELL MADE ' COMPETENT' TO TAKE UP DNA(PLASMID). (2 Marks)
B. EXPLAIN ANY OTHER METHOD BY WHICH AN ALIEN DNA CAN GAIN ENTRY INTO HOST CELL TO FORM RECOMBINANT DNA .(1 Marks)

Q.24. EXPLAIN IN DETAILS
A . SICKLE CELL ANAEMIA (2 Marks)
B. KLINEFELTER'S SYNDROME (1 Marks)

Q.25. A. GIVE THE SCINETIFIC NAME OF PATHOGEN CAUSING MALIGNANT MALARIA IN HUMANS (1 Marks)
B NAME THE KIND OF CELLS THE HIV ATTACKS FIRST (1 Marks)
C. HOW DOES SPLEEN SERVES AS AN ORGAN OF IMMUNITY (1 Marks)

Q.26. A DRAW THE AGE PYRAMIDS FOR HUMAN POPULATION (1 Marks)
B . DEFINE CARRYING CAPACITY. (1 Marks)
C. WHAT IS 'r' in the eaquation dn/dt=rn AND GIVE ITS SIGNIFICANCE.. (1/2 +1/2 Marks)

Q.27. A EXPAND UTR . AND GIVE ITS ROLE . (1/2 + 1/2 Marks)
B. what is frameshift mutation alongwith example. (1 Marks)
C. how tailing and capping is done (1 Marks)

SECTION –D

Q.28. A. SHOW DIGRAMATICALLY THE STAGES OF EMBRYONIC DEVELOPMENT FROM ZYGOTE UTO IMPLANTATION IN HUMANS. (3 Marks)
B. GIVE THE SCHEMATIC REPRESNTATION OF OOGENESIS (2 Marks)

OR

A DRAW A 7-CELLED,8- NUCLEATE NATURE OF FEMALE GAMETOPHYTE. (2 Marks)
B. ZYGOTE IS DORMANT FOR SOMETIMES IN A FERTILISED OVULE . COMMENT (1 Marks)
C. CAN CROSS POLLINATION OCCUR IN CLEISTOGAMOUS FLOWRES JUSTIFY 1(1 Marks)

Q.29 HOW IS BT. COTTON PLANT PRODUCED?.EXPLAIN MECHANISM BY WHIICH PLANT IS ABLE TO RESIST THE INFESTATION BY COTTON BALLWORMS . (5 Marks)

OR

NAME ANY TWO CLONING VECTORS. DESCRIBE THE FEATUIRES REQUIRED TO FACILITATE CLONING INTO A VECTOR. (5 Marks)

Q.30 .GIVE THE EXPERIMENTAL PROOF GIVEN BY MESELSON AND STAHL .IF ECOLI ALLOWDED TO GROW FOR 80 MINUTES THEN WHAT WOULD BE THE PROPORTIONS OF LIGHT AND HYRID DENSITIES DNA MOLECULE?.. (5 Marks)

OR

 EXPLAIN THE SWITCHING 'ON' AND 'OFF' OF LCA OPERON . WHAT IS MEANT BY NEGATIVE REGULATION... (5 Marks)