Class 12 Sample Paper 2025 Biology

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Practice Paper
(2024-25)
Class – XII
Biology (Code: 044)

Time: 3 hours Maximum Marks: 70

General Instructions :
Read the following instructions very carefully and strictly follow them:
 All questions are compulsory.
 The question paper has five sections and 33 questions.
 Section–A has 16 questions of 1 mark each.
Section–B has 5 questions of 2 marks each.
Section–C has 7 questions of 3 marks each.
Section–D has 2 case-based questions of 4 marks each.
and
Section–E has 3 questions of 5 marks each.
 There is no overall choice. However, internal choices have been provided in some questions.
A student has to attempt only one of the alternatives in such questions.
 Wherever necessary, neat and properly labeled diagrams should be drawn.

Section – A
Q. No. 1 to 12 are multiple choice questions. Only one of the choices is correct. Select and write the correct
choice as well as the answer to these questions.
Q. No Question Marks
1. Which function of tapetum is correct ? 1

(a) Helps in pollen wall formation (b) Transportation of nutrients to inner
side of anther
(c) Synthesis of enzyme for separation of (d) All of these
micropore tetrads

2. Which method can be used for women that cannot produce ovum but can.provide 1
suitable environment?

(a) IUD (b) GIFT
(c) IUI (d) ICSI

3. Refer to the given figure. 1

This type of sex determination is found in

(a) grasshoppers and cockroaches (b) birds and reptiles
(c) butterflies and moths (d) honeybees, ants and wasps

Q. No Question Marks
4 Which of the following is not an example of recessive autosomal disease? 1

(a) Haemophilia (b) Cystic fibrosis
(c) Phenylketonuria (d) Sickle-cell anaemia

5 Which of the following criteria should be fulfilled by a molecule to act as a.genetic 1
material ?

i) it should be able to replicate
ii) it should be structurally and chemically stable.
iii) it should be able to undergo slow mutations.
iv) it should be able to express itself in the form of ' Mendelian characters '.

(a) (i) and (ii) (b) (ii) and (iii)
(c) (i),(ii) and (iii) (d) (i),(ii),(iii) and (iv)

6 The given figure shows an example of 1

(a) homologous organs (b) convergent evolution
(c) divergent evolution (d) both (a) and (c)

7 During the life cycle of plasmodium, sexual reproduction takes place in which of the 1
following hosts?

(a) Human (b Female Anopheles mosquito
(c) Male Anopheles mosquito (d) Both (a) and (b)

8 Marijuana is extracted from 1

(a) dried leaves and flowers of hemp (b) ergot fungus
plant.
(c) roots of hemp plant (d) cocoa plant.
9 The given figure represents a typical biogas plant. Select the correct option for A, B, 1
and C respectively.

(a) A is the inlet for cattle dung (b) C is the outlet for the release of biogas
(c) B is the chamber which contains (d) All of these
leftover slurry

Q. No Question Marks
10 Read the given statements and select the correct option. 1

Statement 1 : GMO tomato `Flavr Savr' has increased shelf life and better nutrient
quality.
Statement 2 : This is achieved by reducing the amount of cell wall degrading enzyme
'polygalacturonase' responsible for fruit softening.

(a) Both statements 1 and 2 are correct. (b) Statement 1 is correct but Statement 2
is incorrect.
(c) Statement 1 is incorrect but (d) Both Statements 1 and 2 are incorrect.
Statement.2 is correct

11 The given pie diagram represents the proportionate number of species of major taxa of 1
vertebrates. Identify the groups A and B.

(a) A- Reptiles. B- Birds (b) A- Fish. B- Birds
(c) A- Birds. B- Fish (d) A- Birds. B- Reptiles

12 Gametes of threatened species can be preserved in viable and fertile conditions for 1
long periods using

(a) cryopreservation techniques (b) invitro fertilisation
(c) tissue culture (d) All of these

Question No. 13 to 16 consist of two statements – Assertion (A) and Reason (R).
Answer
these questions selecting the appropriate option given below:

a) Both A and R are true, and R is the correct explanation of A.
b) Both A and R are true, and R is not the correct explanation of A.
c) A is true, but R is false.
d) A is False, but R is true.

13 Assertion: Founder effect may lead to formation of new species. 1

Reason: Founders carry all the parental gene pool to a new location.
14 Assertion: Immunisation is achieved by the successful delivery of vaccines. 1

Reason: Vaccine is a preparation of one or more microbial agents, used to induce
active immunity.

15 Assertion: A piece of DNA inserted into an alien organism generally does not replicate 1
if not inserted into a chromosome.

Reason: Chromosomes have specific sequences called 'ori ' region where DNA
replication is initiated.

16 Assertion: The Nile perch introduced into lake Victoria in East Africa led to the 1
extinction of an ecologically unique assemblage of more than 200 species
of cichlid fish in the lake.

Reason: When alien species are introduced deliberately for economic or other uses,
they often become invasive end cause extnction of indigenous species.

Section – B
Q. No Question Marks
17 Name the hormones involved in regulation of spermatogenesis. 2

18 Explain the mechanism of ' sex determination ' in birds. How does it differ from that of 2
human beings?

19 Explain why hnRNA need to undergo splicing? Where does splicing occur in the cell ? 2

20 How does a simple stirred tank bioreactor differ from sparged stirred-tank bioreactor ? 2

21 What is GEAC and what are its objectives ? 2

Section – C
Q. No Question Marks
22 Mention the roles and locations of the myometrium and endometrium within the human 3
reproductive system.

23 What is Thalassemia? How is Thalassemia different from Sickle-cell anaemia? 3

OR

Is Haemophilia in humans a sex linked or autosomal disorder? Work out a cross in
support of your answer.

24 i. Write a short note on adaptive radiation. 3

ii. Who among the Dryopithecus and.Ramapithecus was more man - like ?

25 From which plant cannabinoids are obtained? Which part of the body is affected by 3
consuming these substances?

26 Explain with reference to PCR 3

a) A specific enzyme helps in application in PCR . Name the bacterium from which
it is isolated and state how its thermostable nature is helpful.

b) Explain its use in molecular diagnosis.

27 CryIAb is introduced in a plant to prevent infestation by corn borer. 3

a) What is the resultant plant referred as ?

b) Summarize the action of the gene introduced. .

28 Name and Explain the processes earthworm and bacteria carry on detritus. 3

Or

Flow of energy through various trophic levels in an ecosystem is unidirectional and
non-cyclic. Explain

Section – D
Q. No Question Marks
29 Read the following passage and answer the questions that follows: - 4

Infertility is the inability to conceive oe produce children even after two years of
unprotected sexual co-habitation. According to recent finding., every fifth Male Indian
in the age group of 18 to 20 years is infertile. Infertility is also found in human females
as well. There are number of causes of infertility. Government of India has established
specialised health care clinics to assist the infertile couples to have children with the
help of these special techniques called ARTs.

I) Name the health clinics which help the infertile couples to have a child.
2) Which techniques is used for direct injection of sperm into ovum of females ?
3) Write the full form of GIFT.
OR
Write the full form of ZIFT.

4) How does the inability of the insemination in male partner or very low sperm count
can be corrected?

30 Read the following passage and answer the questions that follows: - 4

In nature, no living organism, whether it be plants , animals, or microbes, exist in
isolation. They engage in various forms of interaction, giving rise to the formation of
biological communities. These
interactions, involving populations of two or more distinct species, are referred to as
interspecific interactions. These interactions can take on different characteristics,
including positive (beneficial) , negative, or neutral (neither harmed north beneficial)
relationships, encompassing phenomena such as mutualism or parasitism.

1) Mutualism is which type of interaction.
a) positive
b) negative
c) neutral
d) positive and negative

2) Cuscuta is an example of
a) ectoparasitism
b) brood parasitism
c) predation
d) endoparasitism

3) Mycorrhizae is the
a) fungistasis
b) amensalism
c) mutualism
d) antibiosis

4) Cuckoo and Crow are
a) competition
b) ectoparasites
c) brood parasitism
d) predation

Section – E
Q. No Question Marks
31 a) i) In the given diagram, Write names of parts labelled a-g.for Visually-impaired 5
students What is meant by emasculation? When and why does a plant breeder
employ this technique ?

ii) How is pollination carried out in water plants?

OR

What is double fertilisation? Describe the process with diagrams from the stage of
megaspore formation to zygote formation.

b) Cyclosporin- A and Streptokinase are two bioactive molecules name the microbe
which produces these bioactive molecules.
Write their use.

32 i) Differentiate between leading strand and lagging strand. 5
ii) Define Okazaki fragments.
iii) Describe the structure of a nucleosome.

OR

What is transforming principle? Explain it with the help of experiment done by
Frederick Griffith. What do you mean by intron and exon ?

33 a) Explain the role of three micro- organisms as biocontrol agents. 5
b) What is significance of BOD?
c) Give an example for a fungus found in mycorrhiza.

OR

a) What is baker's yeast? Give its application

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