MBOSE Class 12 Question Paper 2026 for Biology

FOR MBOSE CLASS 12 EXAM PREPARATION

MBOSE Class 12 2026
Question Paper ·
Biology
EXAM YEAR TYPE SUBJECT

MBOSE Class 12 2026 Question Paper Biology

Notes · Sample Papers · Previous Year Papers · Mock Tests

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Total No. of Printed Pages—8
HS/XII/Sc/Bio/26
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2026
m s e
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a ( Theory )

Full Marks : 70
Time : 3 hours

The figures in the margin indicate full marks for the questions

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General Instructions :
(i) All questions are compulsory.

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(ii) This question paper consists of 5 (five) Sections—A, B, C, D
and E, and 37 questions.
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(iii) Section—A consists of 12 questions (multiple-choice type)
of which 10 questions are to be answered. Each question
(Q. Nos. 1–12) carries 1 mark.
(iv) Section—B consists of 7 questions (very short-answer type)
of which 5 questions are to be answered. Each question
(Q. Nos. 13–19) carries 1 mark and to be answered in
one word/sentence.
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(v) Section—C consists of 5 questions (short-answer type—I) with
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internal choice. Each question (Q. Nos. 20–24) carries 2 marks

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em(vi) Section—D consists of 10 questions (short-answer type—II)
with alternatives to be answered in 20–30 words.

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carries 3
a marks and to be answered in 30–40 words.
(vii) Section—E consists of 3 questions (long-answer type) with
internal choice. Each question (Q. Nos. 35–37) carries 5 marks
with alternatives to be answered in 60–80 words.

/71 [ P.T.O.

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( 2 )

SECTION—A
Choose and write the correct answer of the following (any ten) :
1×10=10
1. The factor which is essential for genetic equilibrium of
allele frequencies in a population is
(a) No mutation
(b) genetic drift
(c) gene flow
(d) genetic recombination

2. Which of the following cells are present in the egg
apparatus?
(a) Antipodal cells
(b) Synergids
(c) Synergids and one egg cell
(d) Polar nuclei and one egg cell

3. The addition of adenylate residue at the 3 ¢ end of a
template in an independent manner is called
(a) splicing
(b) tailing
(c) capping
(d) split gene

4. Down’s syndrome is caused due to
(a) non-disjunction of chromosome number 21
(b) deletion of chromosome number 21
(c) non-disjunction of chromosome number 16
(d) deletion of chromosome number 16

HS/XII/Sc/Bio/26/71 [ Contd.

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( 3 )

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5. The plant from which opioids are extracted is
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(a) Erythroxylum coca
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(b) Papaver somniferum

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(c) Cannabis
(d) All of the above
6. The first isolated restriction endonuclease is
(a) EcoRI
(b) Hind II
(c) Hind I

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(d) EcoRII

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7. What is the full form of GEAC?

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(a) Genome Engineering Action Committee

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(b) Ground Environment Action
(c) Genetic and Environment Approval Committee
(d) Genetic Engineering Appraisal Committee
8. Factors contributing to population growth are
(a) natality and immigration
(b) natality and emigration
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(c) mortality and emigration

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9. Which of the following is not a functional unit of the
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(b) Decomposition
(c) Stratification
(d) Productivity

HS/XII/Sc/Bio/26/71 [ P.T.O.

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( 4 )

10. In incomplete dominance, the expected phenotypic and
genotypic ratios are
(a) 1 : 1 : 2 and 2 : 1 : 1
(b) 1 : 2 : 1 and 1 : 2 : 1
(c) 1 : 1 : 1 and 1 : 1 : 1
(d) 1 : 1 and 1 : 1

11. In a grass family, the cotyledon is called
(a) plumule
(b) radicle
(c) embryo
(d) scutellum

12. A patient had undergone an organ transplant. To prevent
rejection of the transplanted organ, which immuno-
suppressive agent will be advised for use?
(a) Cyclosporin-A produced from Clostridium butylicum
(b) Cyclosporin-A produced from Trichoderma
polysporum
(c) Statins produced from Monascus purpureus
(d) Statins produced from Streptococcus thermophilus

SECTION—B
Answer the following questions in one word/sentence each
(any five) : 1×5=5

13. Give two examples of terminal method of contraception.
½+½=1

14. What is splicing?

HS/XII/Sc/Bio/26/71 [ Contd.

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( 5 )

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15. Name one substance
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immunotherapy.
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16. What are biodiversity hotspots?

g lofa what colour will be formed if the recombinant
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17. Colonies
DNA fails to get inserted into the gene coding for
b-galactosidase?

18. DNA fragments separated by gel electrophoresis can be
visualized only after staining.
(a) Name the compound used for staining DNA.

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(b) Name the light used for visualization. ½+½=1

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19. A female suffering from Turner’s syndrome has 45
chromosomes. She will have—
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(a) how many autosomes;
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(b) how many X-chromosome(s)? ½+½=1

SECTION—C
20. (a) What is microsporogenesis? What would be the ploidy
of the cells of the tetrad? 1+1=2
Or
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(b) These cells are responsible for the secretion of
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androgen. Name these cells and mention the function
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of their secretion.
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22. What is the role of a vector in genetic engineering? Name
the first artificial cloning vector. 1+1=2

23. Differentiate between convergent and divergent evolution. 2

HS/XII/Sc/Bio/26/71 [ P.T.O.

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( 6 )

24. (a) Draw a well-labelled diagram of an antibody molecule. 2
Or
(b) Name any two microbes used in the following :
½+½+½+½=2
(i) Household products
(ii) Industrial products

SECTION—D
Answer the following questions : 3×10=30
25. When is amniocentesis performed in humans? How is it
misused? 1½+1½=3
26. What is triple fusion? Where does it take place? Name the
nuclei involved in triple fusion. 1+1+1=3
27. (a) Study the diagram given below and answer the
following questions :

(i) Name the diagram.
(ii) Identify the Part A and Part B. 1+1+1=3
Or
(b) Draw the structure of a mature ovum and label it. 3

HS/XII/Sc/Bio/26/71 [ Contd.

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( 7 )

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28. Two water samples A and B were collected. The BOD of
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sample A and sample B were recorded as 300 mg/L and
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500 mg/L respectively. Give the full form of BOD. Which
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sample of water is more polluted? Give reasons. 1+1+1=3

29. ADA ag
is a genetic disorder due to the absence of an
enzyme.
(a) Name the enzyme that is absent.
(b) How can this disorder be corrected? 1+2=3

30. (a) The immune system of a person is suppressed.
(i) Name the disease the person is suffering from.
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(ii) What is the causative organism?
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(iii) Write one mode of prevention for the disease.

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Or a
(b) What are transgenic animals? Give two applications
of transgenic animals. 1+2=3

31. Work out a cross showing marriage between a
haemophilic man (X h Y) and a carrier woman (X h X). Write
the phenotypes of their children. 1½+1½=3

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32. Describe the role of microbes in secondary treatment of
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l a flowers pollinated by insects? a 1+2=3
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(b) Describe adaptive radiation with the help of an
example. 3

34. Define HGP. Write its salient features. 1+2=3

HS/XII/Sc/Bio/26/71 [ P.T.O.

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( 8 )

SECTION—E

35. (a) (i) What is menstrual cycle?

(ii) Explain the different phases of menstrual cycle.
1+4=5
Or
(b) What is population? Explain the different types of
negative interactions in a population. 1+4=5

36. (a) (i) State Mendel’s law of dominance.

(ii) Explain with the help of a suitable cross.

(iii) Give the scientific name of the plant Mendel
used for his experiment. 1+3+1=5

Or

(b) Differentiate between in situ and ex situ conservation.
Describe why we should conserve biodiversity. 2+3=5

37. (a) (i) Write the full form of PCR.

(ii) With the help of a diagram, explain the
mechanism involved in PCR. 1+4=5

Or

(b) What is an operon? Explain the regulation of gene
expression in lac operon with suitable diagrams.
1+4=5

HHH

HS/XII/Sc/Bio/26/71 26K—5340

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