Class 12 Sample Paper 2025 Biology (Mid Term)

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Mid Term Sample Paper 2025-26
-- AGLASEM --
1

Mid Term Examination Practice Paper

Session: 2025-26

Class – XII

Biology (Code: 044)

Time :3 hours Total marks -70

General Instructions:

● Please check this question paper contains 33 questions.
● All questions are compulsory. However, internal choices have been provided in some
questions.
● Attempt only one of the choices in such questions
● The paper is divided into 5 Sections- A, B, C, D and E.
● Section A consists of 16 questions (1 to 16). Each question carries 1 Mark.
● Section B consists of 5 questions (17 to 21). Each question carries 2 Marks.
● Section C consists of 7 questions (22 to 28). Each question carries 3 Marks.
● Section D consists of 2 case study type questions (29 to 30). Each question carries 4
Marks.
● Section E consists of 3 questions (31 to 33). Each question carries 5 Marks.
● Make a labeled diagram where it is necessary.
Que SECTION-A Marks
All the question of this section are multiple choice based.

1 1
1. The intine of a pollen grain is composed of
_______________and _______________

A) Pectin and cellulose

B) Lignin and suberin

C) Lignin and hemicellulose

2

D) Pectin and chitin

2 1
In homozygous condition, a particular gene has

A) different alleles on homologous chromosomes.

B) no alleles on homologous chromosomes.

C) same alleles on homologous chromosomes.

D) same gene on homologous chromosome

3 1
Semen’s fluid part is called as seminal plasma ,the composition of
this fluid is a mix of

I) Seminal vesicles

II) Urethra

III) Prostrate

IV) Bulbourethral gland

A) I,ii, and iii

B) I,ii

C) I,iv

D) I,iii and ,iv

4 1
Grain colour of wheat is determined by three pair of genes as
AABBCC is the darkest and aabbcc is the lightest .this is an
example of the phenomenon

A) Pleiotropy and codominance

B) Pleiotropy and incomplete dominance

3

C) Polygenic and quantitative inheritance

D) Polygenic and qualitative inheritance

5 1
which of the following amino acid residue will constitute the
histone core

A) Lysine and Arginine

B) Asparagine and arginine

C) Glutamine and lysine

D) Aspargine and glutamine

6 1
At a particular locus the frequency of allel B is 0.8 and that of
allele b is 0.3 what would be the frequency of heterozygotes in a
population: (1)

A)0.32

B)0.48

C)0.44

D)0.24

7 1
Match the following

Column 1 Column 2

K)cytokine barrier i)yellow fever

L)Aedes Ii)acid in stomach

4

M)innate immunity Iii)virus infected cell

N)cancer IV)contact inhibition

Codes:

K L M N

A) Ii I iv iii

B) iv Ii I iii

C) Iii I ii iv

D) I iii ii iv

8 1
Read the following statements:

(A) BOD and polluting potential are inversely related.

(B) BOD and polluting potential are directly related.

(C) More the BOD, the easier it is to treat the water.

(D) More the BOD, more will be the harm if released in a water
body.

Which of these is true?

A. (A) and (C) are true and (C) is the reason for (A)

B. (B) and (C) are true and (C) is not related to (B)

C. (B) and (D) are true and (D) is the reason for (B)

D.(A) and (D) are true and (D) is not related to (A)

9 1
A pharmaceutical industry aims to develop a chemical that can
induce immune system modulation in patients with autoimmune

5

diseases and help in alleviating symptoms. Which of the following
microbes should they consider utilizing?

A. Aspergillus niger

B. Trichoderma polysporum

C. Staphylococcus aureus

D. Saccharomyces cerevisiae

10 1
The key tools for recombinant DNA technology are

I) Restriction enzyme

II) DNA polymerase

III) Ligases

IV) Cloning vector

V) Antibiotic resistance

VI) Helicase

A) I,ii,iii, &vi

B) I,ii,iii & iv

C) I,ii,iii & v

D) I,ii,& iii

11 1
What is the primary function of DNA polymerase in the process of
DNA replication?

A) To unwind the double helix structure of DNA

B) To synthesize new DNA strands by adding nucleotides

C) To repair damaged DNA molecules

6

D) To cut DNA molecules at specific

12 1
Which of the following is an application of biotechnology in
medicine?

A) Production of biofuels

B) Development of genetically modified crops

C) Production of insulin through recombinant DNA technology

D) Bioremediation of pollutants

For Question No.-13 to 16: A statement of Assertion is
followed by a statement of Reason. Mark the correct choice
as:

(a)Both assertion and reason are true and reason is the correct
explanation of assertion.

(b)Both assertion and reason are true but reason is not the
correct explanation of assertion.

(c)Assertion is true but reason is false.

(d)Both assertion and reason are false

13 1
Assertion(A): Lichens are an excellent indicators of pollution.

Reason(R): A polluted environment accelerates the growth of
lichens by providing them enormous amount of nutrition.

14 1
Assertion:(A) Morgan coined the term linkage to describe the
physical association of genes on a chromosome.

7

Reason(R): Linkage shows less frequency of parental type
combination of genes

15 1
Assertion (A): Gene therapy is a method of treating a disorder but
cannot cure it.

Reason (R): In gene therapy, cells are drawn from a patient and
the functional gene is introduced into these cells and transferred
back to the patient.

1
Assertion: Family planning is an action plan to attain reproductive
health among people.

Reason: Improved programmes covering reproduction related
areas were propagated by RCH to create awareness among
people.

Section -B

17 2
i)How is parturition induced at the end of pregnancy in a human
female?

ii)Label the parts 1, and 2 in given diagram

Or

8

Why endosperm development precedes embryo development ? if
the exine of mature male gametophyte in angiosperm is
indestructible then how pollen tube formed from it?

18 2
Describe difference in polygenic inheritence and pleiotropy by
illustration of example.

Or

Honey bees are a social insect. How drones and worker bees
development take place in them. Describe the process and its
name.

19 2
What are the findings of the Hershey and chase experiment ?
Who Discovered a semi conservative mode of replication?

20 2
Explain the role of enzymes in the extraction of DNA from
Agaricus (fungus) in its purest form.

21 2
Explain how the insecticidal protein produced by Bacillus
thuringiensis does not kill the bacterium but kill the cotton
bollworm?

SECTION-C

22 3
i)why is follicular phase in menstrual cycle also referred to as
proliferative phase?

Ii)Name one ovarian and one pituitary hormone name involved in
ovulation phase.

9

23 3
i) How is aneuploidy different from polyploidy?

Ii)Name the chromosomal disorder in which affected females develop
rudimentary ovaries?

Or

Study the given pedigree Chart:

I)How many males are there in this chart and how many males
are affected?

II) David is a normal son while his brothers are affected , illustrate
this with the help of a cross?

24 3
In a population of birds, named as B birds with intermediate wing
sizes can effectively fly while birds with either small or large wing
sizes find it difficult to fly.

(i) Which birds are more likely to be naturally selected?

(ii) Based on (i), which type of natural selection does this
phenomenon exemplify?

Iii)What is genetic Drift?

25 3
What happens when:

(i) A newborn is not breastfed.

(ii) A tumour cell enters the bloodstream.

10

iii) A person is transplanted with a kidney without tissue matching.

26 3
i) what is elution?

Ii)How β galactosidase enzyme is considered as better selectable
marker ?

27 3
i) Name a GMO which is rich in vitamin A?

ii)Illustrate gene therapy by way of an example

28 3
What are opioids? Give any two short term effect on body.

SECTION- D

Read the given passages of case based question and answer
the questions.

29 1
India is the most populated country in the world. The alarming
population growth is leading to scarcity of resources for all. We
need to spread awareness for methods of birth control.Various
methods of birth control are available including contraceptives
1
,intrauterine devices,oral contraceptives,injectable contraceptives,
surgical methods and impants.

A) How copper releasing IUDs help in birth control?

B) Why Indian government imposed strict condition for MTP? 2 or
C) Name once a week pill for contraception used by females?
What is the composition of this pill? 2

Or

11

Suggest two ways other than contraception to prevent population
explosion in India?

30
A crime scene investigation team collected DNA evidence from a
suspect's clothing and compared it to DNA samples from several
individuals.The team used PCR to amplify the DNA and then
performed DNA fingerprinting to analyze the results. The Forensic
Department was assigned the responsibility of running the
samples.
2
i)What is the primary purpose of using PCR in DNA
Fingerprinting?

Or

What are the advantages of the above mentioned technique? 1

ii) What is the role of primers in PCR?
1
iii) What is basis of DNA fingerprinting Technique?

Section -:E

31 3
i)Continued self pollination results inbreeding Depression.
Suggest any three mechanisms with brief descriptions to prevent
such conditions.

ii)What is the Final product in sexual reproduction of
Angiosperms?
1
Iii)What are Ex - albuminous seeds?

Or 1
Or
Explain the events that occur during Double fertilization and triple

fusion with the help of a diagram?
5

12

32 1
.i)What are transcriptional products of RNA polymerase III ?

ii)Why Does DNA replication occur in small forks and not in its
entire length?
1
Iii)Two mothers gave birth to babies in a maternity clinic but due
to some negligence their babies were exchanged . One baby’s
father doubted the maternity clinic . Name and describe the
technique which can help the father to find his real baby?
3
Or

I)Describe how Lac Operon operates in presence or absence of
Or
an inducer in E. coli?

Ii)Explain Degenerate codon, & Initiator codon? 3

2

33 3
I)Explain the role of microbes in water treatment of sewage
water?

II)Under which condition will the BOD be lowered in the river? 2
How it will affect aquatic life?

Or
Or
I)How do mycorrhizae act as biofertilisers? Name a genus of
fungi that forms a mycorrhizal association with plants ? 2

Ii)Explain What is IPM? Explain role of ladybird beetle and
3
dragonflies role as biocontrol agent.

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