CBSE Class 12 Biology Sample Paper 2012 Set A

SECTION - A

1. Cite an example of an inverted ecological pyramid. What kind of pyramid of energy would it have? 

2. When is the structure and composition of a community expected to remain unchanged? 

3. At what stage of life is oogenesis initiated in a human female? When does the oocyte complete oogenesis? 

4. After a successful in-vitro fertilisation, the fertilised egg begins to divide. Where is this egg transferred

before it reaches the 8-cell stage and what is this technique named? 

5. AaBb was crossed with aabb. What would be the phenotypic ratio of the progeny? Mention the term to denote this kind of cross. 

6. In F.Griffith’s experiment, how did the nonvirulent strain of Streptococcus Pneumoniae become virulent?

7. State the use of :

(i) Trichoderma with respect to organ transplant, and

(ii) Nucleopolyhedrovirus with respect to pest management 

8. Bacteria that convert milk into curd play two other beneficial roles. What are they? 

SECTION B

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