THE VIJAY MILLENNIUM SENIOR SECONDARY SCHOOL

DHARMAPURI | KRISHNAGIRI
PART III – 33% PORTION EXAM (2024-25)
CLASS : XII MARKS : 70
SUBJECT : BIOLOGY (044) TIME : 3 Hrs
General Instructions:
(i) All questions are compulsory.
(ii) The question paper has five sections and 33 questions. All questions are compulsory.
(iii) 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.
(iv) 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.
(v) Wherever necessary, neat and properly labelled 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. MARK
QUESTION
No. S
During insertional inactivation, the presence of a chromogenic substrate gives blue
coloured colonies if the plasmid in the bacteria does not have an insert. The blue colour
1. 1
is produced by the enzyme
(a) α -glucosidase (b) restriction endonuclease (c) β -galactosidase (d) Taq polymerase
Level of which hormones get elevated by the intake of nicotine?
2. (a) FSH, LH (b) Thyroxine, progesterone (c) Oxytocin, prolactin (d) Adrenaline, 1
nor-adrenaline
The mass of living material at a trophic level at a particular time is called
3. a) Standing rate b) Gross primary productivity 1
c) Standing crop d) Net primary productivity
Study the schematic representation of evolutionary history of plant forms given below
and mention:

4. 1
(i). The plant forms ferns and conifers are most related to.
(ii) The nearest ancestors of flowering plants.
(iii) The most primitive group of plants.
(iv) Common ancestry of Psilophyton provides to.
A) (i) Seed ferns (ii) Psilophyton iii)Chlorophyte ancestor(iv) Ferns, conifers and
seeds ferns
B) (i)Psilophyton (ii) Ferns, conifers and seeds ferns (iii) Seed ferns (iv)
Chlorophyte ancestor
C) (i)Psilophyton(ii)Seed ferns,(iii)Chlorophyte ancestor(iv) Ferns, conifers and
seeds ferns
D) (i) Ferns, conifers and seeds ferns (ii)Seed ferns,(iii)Chlorophyte ancestor(iv)
Psilophyton
I Interferons are most effective in making non-infected cells resistant against the spread
5. of which of the following diseases in humans? 1
(a) Ascariasis (b) Ringworm (c) Amoebiasis (d) AIDS
 Select the hormone-releasing intra-uterine devices.
6. (a) Lippe’s loop, Multiload 375 (b) Vault, LNG-20 1
(c) Multiload 375, Progestasert (d) Progestasert, LNG-20

The basic procedure involved in the synthesis of recombinant DNA molecule is depicted
below. The mistake in the procedure is

7. 1

(a) enzyme polymerase is not included (b) the mammalian DNA is shown double
stranded
(c) two different restriction enzymes are used (d) only one fragment is inserted
The permissible use of the technique amniocentesis is for
(a) detecting sex of the unborn fetus
(b) artificial insemination
(c) transfer of embryo into the uterus of a surrogate mother
(d) detecting any genetic abnormality

8. 1

Consider the statements given below regarding contraception and answer as

directed thereafter-
A. Medical Termination of Pregnancy (MTP) during first trimester is generally
safe.
B. Generally chances of conception are nil until mother breast feeds the infant
up to two years.
C. Intrauterine devices like Copper T are effective contraceptives
D. Contraception pills may be taken up to one week after coitus to prevent
9. conception. 1
Which two of the above statements are correct?
a. C, D
b. A, C
c. A, B

d. B, C

Which of the following ecosystems is most productive in terms of net primary

production?
10 1
A) Deserts B) Tropical rain forests C) Oceans D) Estuaries

Anayaa told her younger brother that forelimbs of man and cheetah are
structurally similar, though they perform different functions.
11 1
Do you agree with Anayaa? Such organs are called --------------
A) No, Analogous B) No, Homologous C) Yes, Analogous D) Yes, Homologous
12 1

Approximately how much of the solar energy that falls on the leaves of a plant is
converted to chemical energy by photosynthesis?
a. Less than 1%
b. 2-10%
c. 30%
 d. 50%

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 but R is not the correct explanation of A
C. A is true but R is false
D. A is false but R is true

Assertion : In barrier methods, ovum and sperms are prevented from physical meeting.
13 Reason : Barrier methods are used during coitus, to prevent the entry of ejaculated 1
semen into the female reproductive tract.
Assertion: An antibody is a protein molecule made by the lymphocytes.
14 Reason: An antibody binds to a specific antigen and neutralizes its odd effects. 1

Assertion: Agrobacterium is used to deliver foreign gene in animals.

15 1
Reason: Agrobacterium has Ti plasmid.
Assertion : Coacervates are believed to be the precursors of life.
16 Reason : Coacervates were self-duplicating aggregates of proteins surrounded 1
by lipid molecules.

Section - B

Attempt either option A or B:

a) How do DNA fragments migrate and resolve in a Gel electrophoresis?

b) How pure DNA fragments are made observable in the visible light?

17 2

OR
Enumerate the two properties of cancer cells that distinguish them from normal cell.

Attempt either option A or B:

Identify A, B, C and D in the following table:

Name of the human Name of the causal
Disease bacteria/virus Specific organ or its part affected

1. Typhoid Salmonella typhi A

2. Common cold B C
18 3. Pneumonia Streptococcus pneumoniaeD

OR

Draw a schematic sketch of pBR322 plasmid and label the following in it:
(a) Any two restriction sites.
(b) ori and rop genes.
(c) An antibiotic resistant gene
The arrangement of structural genes in transcriptions unit is not similar in prokaryotes
and eukaryotes. Explain.
19 2
The figure given below shows 3 sperm A, B and C.

21. Attempt either option A or B: 2

 An orchid plant growing on a mango tree. Explain this interaction classifying among
mutualism, commensalism or predation.
OR
In a botanical garden of a city there is a huge banyan tree growing on which
hundreds of birds and thousands of insects live. Draw the pyramids of numbers and also
biomass represented by this community. Comment giving reasons on the two different
pyramids drawn.
Section - C
(a) Why do the symptoms of malaria not appear immediately after the entry of
sporozoites into the human body when bitten by female Anopheles? Explain.
22 (b) Give the scientific name of the malarial parasite that causes malignant malaria in 3
humans.

i) Why primary immune response is considered as low intensity than anamnestic

response?
ii) What types of the lymphocytes are related with the primary and secondary
23 3
immune responses?
iii)Which type of the immune response is responsible for the graft rejection?

What factors cause fluctuation in the density of population within a given

period, in a given habitat? Explain each of them.
24 3

Define decomposition and describe the processes and products of

25 3
decomposition.
Given below is a diagrammatic representation of the experimental setup used
by SL Miller for his experiment.

26 3

(i) Write the names of different gases contained and the conditions set for the
reaction in the flask A.
(ii) State the type of organic molecule he collected in the water at B.
(iii) Write the conclusion he arrived at.
Draw each step of PCR. Why Thermus aquaticus is important during the process?
27 3

Explain Darwinian theory of evolution with the help of one suitable example.
28 State the two key concepts of theory. 3

Section - D
 A population of 100 spotted deer was living without any carnivores in an
enclosure of a few hectares of rich tropical forest land. Deer census was taken
after a few years. Now study the graph given below and answer the questions
that follow

29 4

(a) Identify the curve that represents the deer population. (1m)
(b) Write the equation for the curve A and B. (1m)
(c) Is it a realistic one? Justify. (2m)
OR
(d) What would have happened if the carnivores were also present in
ecosystem? (2m)

RESTRICTION ENZYMES:

In the year 1963, the two enzymes responsible for restricting the growth of
30 bacteriophage in Escherichia coli were isolated. One of these added methyl 4
groups to DNA, while another cut DNA. The later was called restriction
endonuclease. It was found that this enzyme always cut DNA molecules at a
particular point by recognising a specific sequence of six base pairs. During the
naming of these enzymes the specific rules are used. On the basis of the
cutting of the DNA and cutting edge of the DNA, they are also classified.

Writethe answer of the questions give following-

a. Which was the first restriction endonuclease isolated?
b. In EcoRI, what first letter denotes?
c. In EcoRI, what is the meaning of ‘R’ and ‘I’?
Or
How the exonuclease and endonuclease are different?

Section - E

Study the diagram showing replication of HIV in Humans and answer the
31 5
questions that follows
 i) What type of viruses causes AIDS? Name its Genetic Material. Or the group
name of such viruses which possesses this type of genetic material.
ii) Does this virus follows central dogma or it deviates from it ?
iii) Name the enzyme “B” acting on “X” to produce molecule “C”.
iv) What does NACO means and write its role in preventing AIDS?
v) What do you mean by the statement that “ Incubation period for AIDS
may vary from one month to ten years”.
OR
i) Describe the three different ways by which natural selection can affect the
frequency of a heritable trait in a population.
(ii) How does Hardy-Weinberg equation explain genetic equilibrium?
(iii) Describe how this equilibrium gets disturbed which may lead to founder
effect.
Define ecological pyramids and describe with examples, pyramids of number
and biomass.
0R
i) Which protozoa cause malaria? Write a short note on the life cycle of the malarial
32 parasite. 5
ii) Trace the life cycle of Malarial Parasite in the human body when bitten by an infected
female Anopheles.
iii) Write some prevention measures to avoid infectious diseases.
A. Mention the cause and the body system affected by ADA deficiency in
humans.
B. Name the vector used for transferring ADA-DNA into the recipient cells in
humans. Name the recipient cells.
C. Mention a possible permanent cure for a ADA deficiency patient.
D. What is gene therapy? Mention its types.
OR
A large number of married couples the world over are childless. It is shocking
33 to know that in India the female partner is often blamed for the couple being 5
childless.
(a) Why in your opinion the female partner is often blamed for such situations
in India? Give any two views.
(b) State any two reasons responsible for the cause of infertility.
(c) Suggest a technique that can help the couple to have a child where the
problem is with the male partner