MBOSE Class 12 Question Paper 2020 for Biology

Total No. of Printed Pages—7
HS/XII/Sc/Bio/NC/20

2020

BIOLOGY

( New Course )

Full Marks : 70

Time : 3 hours

General Instructions :

(i) Write all the answers in the Answer Script.

(ii) Attempt all Parts of a Group serially in one place.

(iii) All questions are compulsory.

(iv) The figures in the margin indicate full marks for the
questions.

(v) This question paper consists of 5 (five) Groups—A, B,
C, D and E.

Group—A consists of 5 questions (Multiple-choice
type). Each question (Q. Nos. 1–5) carries 1 mark.

Group—B consists of 5 questions (Very short-answer
type). Each question (Q. Nos. 6–10) carries 1 mark and
to be answered in one sentence.

Group—C consists of 6 questions (Short-answer
type–I). Each question (Q. Nos. 11–16) carries 2 marks
and to be answered in 20–30 words.

/40 [ P.T.O.

( 2 )

Group—D consists of 11 questions (Short-answer
type–II). Each question (Q. Nos. 17–27) carries
3 marks and to be answered in 30–40 words.

Group—E consists of 3 questions (Long-answer type).
Each question (Q. Nos. 28–30) carries 5 marks with
alternatives to be answered in 60–80 words.

GROUP—A
Choose and write the correct answer of the following : 1×5=5

1. A typical angiospermic embryo sac at maturity is
eight-nucleate and

(a) one-celled

(b) four-celled

(c) seven-celled

(d) eight-celled

2. Which of the following causes biomagnification?

(a) SO2 and CO2

(b) CO2 and NO2

(c) Mercury and DDT

(d) Methane and CO2

HS/XII/Sc/Bio/NC/20/40 [ Contd.

( 3 )

3. Variety of beaks of finches that Darwin found in
Galapagos islands was due to

(a) adaptive radiation

(b) convergent evolution

(c) genetic drift

(d) artificial selection

4. Elephantiasis is a disease caused by

(a) Ascaris

(b) Wuchereria

(c) Taenia

(d) Plasmodium

5. DNA sequences that code for protein are known as

(a) introns

(b) exons

(c) control regions

(d) intervening sequences

HS/XII/Sc/Bio/NC/20/40 [ P.T.O.

( 4 )

GROUP—B

6. What are the characters of flowers pollinated by insects? 1

7. Define biofertilizers. 1

8. State what ‘standing crop’ of a trophic level
represents. 1

9. What is an endemic species? 1

10. Define inbreeding. 1

GROUP—C

11. Give the diagrammatic representation of the process of
spermatogenesis. 2

12. What is the full form of PCR? State its one use in
biotechnology. 1+1=2

13. Define greenhouse effect. Name the greenhouse gases.
1+1=2

14. Mention the objectives of biofortification. 2

HS/XII/Sc/Bio/NC/20/40 [ Contd.

( 5 )

15. What are the benefits of genetically modified crops? 2

16. Define triple fusion. What is the product of this
process? 1+1=2

GROUP—D

17. Write a short note on apomixis. 3

18. List three main differences between DNA and RNA. 3

19. Describe the process involved in the conversion of milk
into curd. 3

20. What essential features must be present in a cloning
vehicle? 3

21. Explain mutualism giving suitable examples. 3

22. What are the major causes of loss of biodiversity?
Describe any one of them. 1½+1½=3

23. Define restriction enzyme. Why is it so called? Give one
example. 1+1+1=3

HS/XII/Sc/Bio/NC/20/40 [ P.T.O.

( 6 )

24. Draw a well-labelled diagram of an antibody. 3

25. What is tumour? Differentiate between benign and
malignant tumour. 1+2=3

26. Mention some important features of Human Genome
Project (HGP). 3

27. What is natural method of contraception? Briefly
describe any one method. 1+2=3
Or
What are the advantages of tissue culture? 3

GROUP—E

28. Define fertilization. Where does this process take place
in female body? Describe the process of fertilization in
human body. 5

Or

State Mendel’s law of independent assortment. Describe
the law with an appropriate dihybrid cross. 1+4=5

29. What is water pollution? What are its causes? State
some of the effects of water pollution on environment.
1+4=5

HS/XII/Sc/Bio/NC/20/40 [ Contd.

( 7 )

Or

Explain the flow of energy in an ecosystem with the help
of a diagram. 5

30. Discuss lac operon model with the help of a diagram. 5

Or

Give the salient features of genetic code. 5

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HS/XII/Sc/Bio/NC/20/40 20K