BHARATIYA VIDYA BHAVAN, KOCHI

MODEL EXAMINATION 2024-2025

BIOLOGY (044)
SET- I
Class : XII Marks : 70
Time : 3 Hours
General Instructions:
1. All questions are compulsory.
2. The question paper has five sections.
3. Section–A has questions of 1 mark each; Section–B has
questions of 2 marks each; Section– C has questions of 3
marks each; Section– D has case-based questions of 4 marks
each; and Section–E has questions of 5 marks each.
4. 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.
5. 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 QUESTIONS Marks

1 Mammary ampulla is composed of 1

a. mammary ducts
b. mammary tubules
c. mammary lobes
d. lactiferous ducts
2 Identify the group in which all the plants are pollinated 1
by the same agent.
a. Hydrilla, Zostera and Vallisneria
b. Cannabis, Hydrilla and Water Lily
c. Vallisneria, Water Hyacinth and Water Lily
d. Commelina, Hydrilla and Wheat
3 Which of the following statements does not hold true 1
for restriction enzymes?
a. It recognizes a palindromic sequence
b. It can either be an endonuclease or exonuclease
c. It is isolated from bacteria
d. Same restriction enzymes can produce different
kind of sticky ends in different DNA molecules
4 A person with trisomy of chromosome 21 shows 1
(i) Furrowed tongue
(ii) Characteristic palm crease
(iii) Rudimentary ovaries
(iv) Gynecomastia
Select the correct option from the choices below
a. (ii) and (iv)
b. (i), (ii) and (iv)
c. (ii) and (iii)
d. (i) and (ii)
5 Listed below are some amino acids and their 1
corresponding mRNA codons:
Amino acid mRNA codons
Phenylalanine UUU
Lysine AAG
Arginine CGA
Alanine GCA
 Select the DNA sequences that would code for the
following polypeptide sequence:
Polypeptide: Alanine-Arginine- Lysine- Phenylalanine
a. CGT GCT TTC AAA
b. CGT GCT TTC TTT
c. CGU GCU UUC AAA
d. CGU GCU UUC TTT
6 1

A schematic representation of the lac operon of E.coli is

given above, Identify the components A,B,C and D and
select the correct answer from the options given below.
a. A -Inducer, B -Permease, C - 𝛽- galactosidase,
D -Transacetylase
b. A -Inducer,
B-Transacetylase,C-Permease,D-𝛽-galactosidase
c. A-Inducer, B- 𝛽-galactosidase, C-Permease,
D-Transacetylase
d. A-Repressor, B-𝛽 galactosidase, C-Permease,
D- Transacetylase
7 Biogas produced in the STP is the result of 1
a. Anaerobic digestion of flocs.
b. Aerobic digestion of flocs.
c. Anaerobic digestion of activated sludge.
d. Aerobic digestion of activated sludge.
8 Match the columns and select the correct option. 1
Column I Column II
A.Chalaza 1. The region where the body of
the ovule fuses with the
funicle.
B. Nucellus 2. The protective envelopes of
the ovule.
C. Integument 3. The stalk of the ovule.
4. Mass of parenchyma cells
D.Hilum with abundant reserve food
material.
5. The basal part of the ovule.
a. A -5, B -4, C -3, D -2
b. A -5, B -4, C -2, D -1
c. A -4, B -3, C -2, D -1
d. A -2, B -4, C -1, D -5
9 Analysis of meteorites content supports 1
a. Chemical evolution
b. Biological evolution
c. Origin of life
d. Origin of biodiversity
10 Study the following statements. 1
(i) Euchromatin is loosely packed chromatin.
(ii) Heterochromatin is transcriptionally active.
(iii) Histone octamer is wrapped by negatively charged
DNA in nucleosome.
(iv) Histones are rich in lysine and glutamine.
The correct statements are
a. (i) and (iii)
b. (i), (iii) and (iv)
c. (ii) and (iii)
d. (ii) , (iii) and (iv)
11 If the maternal grandfather of a boy is colourblind, 1
maternal grandmother is normal and father is normal,
then what are the chances that this boy could have
colour blindness?
a. 25%
b. 50%
c. 75%
d. 0%
12 Biological farming approaches mainly focus on 1
1. Eradication of pests.
2. Eradication of predators.
3. Managing the pests using checks and balances.
4. Biodiversity analysis to control pests.
Choose the appropriate statements with respect to the
question.
a. 1 and 4
b. 1 and 2
c. 3 and 4
d. 2 and 3
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 (A) : Geitonogamy is pollination between 1
two flowers of the same plant.
Reason (R) : In geitonogomy the pollinating flowers
are genetically different from each other.
14 Assertion (A) : Addition or deletion of a single base in 1
a cistron produces an entirely new polypeptide.
Reason (R) : Addition or deletion of a single base in a
cistron leads to a change in the reading frame from the
point of addition / deletion.
15 Assertion (A) : Bottled fruit juices are clearer as 1
compared to those made at home.
Reason (R) : Pectinases and lipases are used to clarify
fruit juices.
16 Assertion (A) : A quantitative character is controlled 1
by three or more genes, hence it is also known as
polygenic inheritance.
Reason (R) : In pleiotropy, a single gene manifest
multiple phenotypes.
SECTION - B
17 Attempt either option A or B 2
A.
(1) Human embryos with 8 to 16 cells undergo
many changes to get physically and
physiologically connected to the mother. Evaluate
the statement.
(2) A human embryo with very few cells gets
wonderfully transformed into a fully grown baby.
Analyse.
OR
 B.
(1) The human male ejaculates about 200 to 300
million sperm during a coitus, however the ovum
is fertilized by only one sperm. How does the
ovum block the entry of additional sperms?
(2) All copulations will not lead to fertilization.
Why?
18 Study the diagram of egg apparatus given below and 2
identify the part labeled A. State its function.

19 Identify the habit forming substance having the given 2

chemical structure. Give the scientific name of its
source plant and also outline its effect on our body.

20 Attempt either option A or B 2

A.IUDs are ideal contraceptives for the females who
want to delay the pregnancy and/or space children.
Verify the statement.
OR
B. STIs are a major threat to a healthy society. State
any four complications which might affect STI
patients.
21 Attempt either option A or B 2
A.(1) Organisms occupy a place in their habitats
according to their feeding relationship with the
other organisms.This in turn decides their position
in a food chain. Suggest suitable ecological terms
for the same.
(2) Differentiate between DFC and GFC.
OR
B. (1) The food and energy relationship between
organisms can be represented in different ways in
ecology. Design a suitable ecological
representation to show the decrease in the energy
levels in an ideal ecosystem like a grassland.
(2) Isolated food chains do not exist in nature.
Substantiate.
SECTION C
22 Many copies of a specific gene of interest are required 3
to study the detailed sequencing of bases in it. Name
and explain the process that can help in developing
large number of copies of this gene of interest.
23 Examine the given diagram and comment on it. 3
Interpret the relevance of CL.
24 a) Trace the development of male gametophyte in an 3
angiosperm.
b) Name the cell in it that develops into male
gametes.
25 Biofertilizers are organisms which can be used to enrich 3
the nutritive quality of soil. They can be autotrophic or
heterotrophic microbes. Construct a table showing the
different classes of biofertilizers, their habitats and the
effects on soil and crop.

26 Observe the segment of mRNA given below 3

Explain the steps involved to make fully processed

hnRNA.

27 Draw a diagram of E.coli cloning vector pBR322 to 3

show the following
a) Any one restriction endonuclease site in
tetracycline resistance gene.
b) ‘ori’ site
c) ‘rop’ site.What does it code for in pBR322?
d) Why is it essential to have ‘selectable marker’ in a
cloning vector?
28 Predators in nature are prudent. Prey species have 3
evolved various defenses to lessen the impact of
predation. Explore the given statements and justify.
 SECTION D
29 Six hundred miles off the coast of Ecuador lie the 4
volcanic islands of the Galapagos famous for the wealth
of unique plants and animals found nowhere else in the
world. It has become the source for the basic process of
evolution. Galapagos remains as the living laboratory
for scientists today.

A.Study the given picture and correlate it with the

basic process of evolution.
B. Compare it with the pattern of evolution shown by
Australian marsupials and placental mammals.
Attempt either subpart C or D
C. State the two key concepts of Darwinian Theory
of evolution.
OR
D.State modern synthetic theory of evolution.
30 A person is suffering from bouts of fever, diarrhoea and 4
weight loss. He also shows swollen glands and lymph
nodes. He is subjected to some diagnostic tests and is
advised to have antiretroviral drugs.
A.Analyse the given paragraph and identify the
health disorder. Summarise the changes undergone
by his infected cells.
B. List out some opportunistic infections which can
worsen his health condition.
 Attempt either subpart C or D
C. Suggest some effective preventive measures.
OR
D.Mention an organisation which is actively
engaged in controlling the same.
SECTION E
31 Attempt either option A or B 5
A.Stability is one of the properties of genetic
material, was very evident in one of the early
experiments in genetics. Name the scientist and
describe the experiment. State the conclusion he
arrived at.
OR
B. (i) A garden pea plant bearing Terminal Violet
flowers when crossed with another pea plant
bearing Axial Violet flowers produced Axial
Violet flowers and Axial White flowers in the ratio
of 3:1. Work out the cross showing the genotypes
of the parent pea plants and their progeny.

(ii) Name and state the law that can be derived

from this cross and not from a monohybrid cross.
32 Attempt either option A or B 5
A.
(i) Cotton bollworms enjoy feeding on cotton
plants,but are killed when they feed on Bt
cotton.Justify the statement.
(ii) Mention the role of cry I Ab.
(iii) Biotechnologists refer to Agrobacterium
tumefaciens as a natural genetic engineer of
plants. Give reasons to support the statement.
 OR
B.
(i) Mention the cause and the body system
affected by ADA deficiency in humans.
(ii) What is gene therapy?How is it carried out to
treat the patients suffering from this disease?
(iii) Name the other two methods for the treatment
of this disease.
(iv)State the possibility of permanent cure for this
disease.
33 Attempt either option A or B 5
A.
There were five episodes of mass extinction in the
history of life on earth. The current loss of
biodiversity is yet another episode.
(i) Point out the features of the current loss of
biodiversity.
(ii)How does the loss of biodiversity of a region
affect the ecosystem?
(iii)Find out the Evil Quartet which accelerates
biodiversity loss.
OR
B.
(i) Discuss the importance of species diversity to
the ecosystem.
(ii) The diversity of plants and animals is not
uniform throughout the globe. Support it with
relevant examples.
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