VELAMMAL BODHI CAMPUS
BIOLOGY CT-2 MODEL QUESTION PAPER
SECTION A (1X16=16)
1.A sample of normal double-stranded DNA was found to have thymine content of 27%. What will be
the expected proportion of guanine in this strand?
A. 23% B. 32% C. 36% D. 73%
2. Observe the schematic diagram that depicts a small section of nucleic acid. The bases in two
strands are paired through hydrogen bonds that are shown by the dark lines. Identify the correct
sequence of nucleotide in the 5’-3’ direction.
A. GCAT B. CGTA C. TAGC D. ATCG
3. In E.coli, the lac operon gets switched on when lactose is
A. present in the medium and it binds to the repressor.
B. not present in the medium and the repressor binds to the operator.
C. not present in the medium and RNA polymerase binds to the operator.
D. Active lactose present in the medium binds to RNA polymerase
4. The following diagram shows a fragment of DNA which is going to be transcribed, the upper strand
with polarity 3’ to 5’ is the template strand: 3´ ATTGCC 5´ 5´ TAACGG 3´ After transcription the
mRNA can be represented by:
A. 5´ AUUGCC 3´ B. 5´ AUUGCC 3’ C. 5´ UAACGG 3´ D. 5´ GGCAAU 3´
5. Adaptive radiation leads to which of the following?
A. Increased competition among species
B. Decreased speciation rates
C. Limited morphological diversity among species
D. Rapid divergence of traits among populations inhabiting a given geographical area.
6. In a given population of 2000 individuals, 80 births and 125 deaths were reported over a given
period of time. Which of the following graphs will correspond to it?
7. A plant native to South America, which produces cocaine is
(a) Erythroxylum coca (b) Atropa belladonna (c) Datura stramonium (d) Papaver somniferum
8. The Hardy-Weinberg principle cannot operate if
(a) the population is very large
(b) frequent mutations occur in the population
(c) the population has no chance of interaction with other populations
(d) free interbreeding occurs among all members of the population
9. Which lymphoid organ atrophies with age?
(a) Bone marrow (b) Peyer's patches (c) Thymus (d) Spleen
10. A biologist studied the population of rats in a barn. He found that the average natality was 250 ,
average mortality 240, immigration 20 and emigration 30 . The net increase in population is
(a) 05 (b) zero (c) 10 (d) 15.
11. Which interaction is shown when the invasive prickly pear cactus brought under control after
introduction of moth from its natural habitat?
(a) Predation (b) Amensalism (c) Mutualism (d) Competition
12. Which of the following is not an example of in situ conservation?
(a) Biosphere reserves (b) National parks (c) Wildlife sanctuaries (d) Zoological parks
ASSERTION REASON (13 TO 16)
(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): Deoxyribonucleoside triphosphates serve dual purposes.
Reason (R): They act as proof readers and provide energy.
14. Assertion : Emigration is outward movement of some individuals from local population. Reason :
Emigration is caused by occurrence of deficiencies and calamities.
15. Assertion : Many endemic species are seen to flourish in sacred forests. Reason : Sacred forests
are undisturbed forest patches and biodiversity rich areas
16. Assertion : Mycorrhizae represent a mutually beneficial interspecific interaction of fungi with
roots of higher plants. Reason : In a mutualistic relationship, both the organisms enter into some sort
of physiological exchange
SECTION B (5X2=10)
17. A. The schematic representation given below shows a DNA strand and two types of mutations in
the DNA strand.
(i) Identify the type of mutation exhibited in I and II. (ii) Which of the above mutation is
more harmful? Give reason.
OR
B. Given below is a schematic representation of a mRNA strand
(i) In the above sequence identify the translational unit in mRNA. (ii) Where are UTRs
found and what is their significance?
18. Given below is the relationship between the HIV levels in the blood and helper T cell count in a
person detected with AIDS. Study the relationship and answer the questions that follow.
A. What kind of relationship is observed in the virus levels and the immune response after some
days of the initial infection?
B. Does it completely clear the virus from the body permanently? Give reason for your answer.
19. (a) It is generally observed that the children who had suffered from chicken-pox in their
childhood may not contract the same disease in their adulthood. Explain giving reasons the basis
of such an immunity in an individual. Name this kind of immunity. (b) What are interferons?
Mention their role
20.
The above graph show species-area relationship. Write the equation of the curve ‘a’ and explain
it. OR
How does over-exploitation of beneficial species affect biodiversity? Explain with the help of
one example
21. (a) Rearrange the following in the correct order of their appearance on earth between two
million years and 40,000 years back.
Neanderthals, Australopithecines, Homo erectus and Homo habilis.
(b) Which one of the above (i) had the largest brain size (ii) ate fruits?
SECTION C (7X3=21)
22.
A. During the process of replication and transcription the pairing of nitrogenous bases is not
similar. Explain. B. How is the above process modified in a retrovirus? Name the process. C.
Justify why during the process of transcription only a segment of DNA is copied into RNA.
OR
Carefully examine structures A and B of pentose sugar given below. Which one of the two is more
reactive? Give reasons
23. A. Name and explain the mechanism where two species competing for the same resource co-exist.
B. What does Gause‘s exclusion principle state? Does it apply in the above situation? Explain.
24. (a) The given flow chart highlighting the steps in DNA fingerprinting technique. Identify a, b, c, d,
e and f
(b) List any two applications of DNA fingerprinting technique
25. A particular species of wild cat is endangered. In order to save them from extinction, which is a
desirable in situ or ex situ? Justify your answer and explain the difference between the two
approaches.
26. Convergent evolution and divergent evolution are the two concepts explaining organic evolution.
Explain each one with the help of an example.
27. Write the scientific names of the causal organisms of amoebiasis, elephantiasis and ringworm in
humans. Mention the body parts affected by them.
28. (a) The barriers in the innate immunity are given in the following table. Identify A, B, C, and D.
(b) Why sharing of injection needles between two individuals is not recommended?
OR
SECTION D CASE BASED QUESTIONS (2X4=8)
29.Given below is the pattern of temperature in a person suffering from a non-viral disease
transmitted by mosquitoes. Study the graph and answer the questions that follow:
A. Explain the factor(s) responsible for this pattern of temperature. (1)
B. How does this pathogen multiply in the human body? (2)
Attempt either subpart C or D.
C. How is this infection transmitted to humans? (1)
OR
D.Which stages of the life cycle of this pathogen are completed in the mosquito’s gut? (1)
30. Study the schematic representation of the genes involved in the lac operon given below and
answer the questions that follow:
p i p o z y a
(a) Identify and name the regulatory gene in this operon. (1M)
(b) What is the role of inducer in the given figure? (1M)
(c) Why is the lac operon’s regulation referred to as negative regulation? (2M)
OR
(c) Name the inducer molecule and the products of the genes ‘z’ and ‘y’ of the operon. Write the
functions of these gene products
SECTION E (3X5=15)
31. Attempt either option A or B.
A. (i) Why is there a need to conserve biodiversity? (Any two reasons) (ii) Name and explain any two
causes that are responsible for the loss of biodiversity.
OR
B. (i) Name the two types of desirable approaches to conserve biodiversity? Explain with examples
bringing out the difference between the two types. (ii) State the features of a stable biological
community?
32. (a) What is a genetic code? (b) Explain the following: (i) Degenerate codon; (ii) Unambiguous
codon; (iii) Initiator codon
OR
During course of evolution why DNA was chosen over RNA as genetic material? Give reasons by
first discussing the desired criteria in a molecule that can act as genetic material and in the light of
biochemical differences between DNA and RNA.
33. An experiment ' X ' provided evidence in support of ' Y '. In this experiment, four gases were
circulated 'A', 'B', 'C', and 'D' in an air tight apparatus and electrical discharge from electrodes was
passed at 800∘C. The mixture of gases were passed through a condenser. After a week, the chemical
composition of the liquid inside the apparatus was analysed. The results provided evidence through
which ' 𝑌 ' was more or less accepted. (i) Identify gases A, B, C, D. (ii) Which theory of origin of life
is supported by the above experiment? (iii) Draw a diagrammatic representation of experiment X. (iv)
What does A, B, C and D together produced in the experiment X ?
OR
Refer the table given below and answer the following questions. Table : Types of Interaction
(a) Identify P, Q, R, S, T and U. (b) (i) An orchid growing as an epiphyte on a mango branch is an
example of which interaction? (ii) Name the type of interaction seen between wasp and fig tree. (c)
Give one example of interaction ‘P’.
