CBSE Class 12 Biology Question Paper 2020 Set A

CBSE Class 12 Biology Question Paper 2020 Set A. Students can download the last year board exams question papers using the link below. Free download of examination question papers with solutions. Last 10 year question papers should be practised to get better marks in examinations. 

SECTION – A 

1 The amino acid Serine has 6 m R.N.A codons-UCU UCC UCA UCG AGU AGC. 

Give the D.N.A. codons for it. 

2. Which disorder is caused in humans by the presence of an extra 21stautosome? 

3. How many cells are found in a typical embryosac? Name them. 

4. Name the two types of cloning vectors. 

5. Why is thermostable D.N.A. polymerase needed in amplification (Genetic Engineering)? 

SECTION – B 

6. Draw a labelled diagram of any one of the following :-

 Human Sperm

 (OR) 

Male gametophyte of angiosperms. 

7. How does a test cross help in identifying the genotype of an organism? Explain. 

8. What is the role of lysing enzymes in Biotechnology? 

9. How does BOD indicate the level of pollution of water? 

10. What is meant by Biotic potential? 

SECTION – C 

11. a) How do copper and hormone releasing IUD’S act as contraceptives? 

b) What do you mean by seasonal breeders? 

12. i) Some organisms like honey bees are called parthenogenic animals. GIVE Reason. 

ii) Zygote forms the major link between one generation and those of the next generation organism- What is the fate of the zygote in organism which show:- 

a) Haplontic life cycle. 

b) Diplontic life cycle.

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