(n) Section D - questions number 29 and 30 are case-based questions.

Each question carries 4 marks. Each guestion has subparts with internal
choice in one of the subparts.
(vi) Section E - questions number 31 to 33 are long answer type questions
Each question carries 5 marks.
(vii) There is no overall choice. However, an internal choice has been provided
in Sections B, D and E of the question paper. A candidate has to write
answer for only one of the alternatives in such questions.
(1X) Wherever necessary, neat and properly labelled diagrams should be
drawn.

SECTION - A
Q. No. 1to 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.
1. Which of the following is the common ancestor of cycads and
dicotyledons
of angiosperms?
(a) Ginkgos (b> Seed ferns
(c) Conifers (d) Gnetales

2. Antibiotics produced by microbes are regarded as one of the

most significant
discoveries of the twentieth century and have greatly contributed towards
the welfare of the human society. Which one of the
following is not true
about antibiotics?
(a) They are the chemicals produced by microbes that kill or retard the
growth of other microbes.
(b) First antibiotic was discovered by Alexander Fleming.
(c) They are produced by prokaryotes only.
(d) Penicillin, the first antibiotic was used to treat the soldiers wounded
in World War II.

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 3. A tall pea plant bearing violet flowers with genotype TTVv is crossed witn
adwarf pea plant bearing white flowers. What will be the percentage of
tall plants with white flowers in the progeny?
vjlet
(a)50% (b) 100%
(c) 75% (d) 25%

4. The term "totipotency' refers to

(a) the ability of an organism to regenerate its lost parts.
(b), the ability of a plant cell to grow into an entire plant.
(c) the techniques of growing immature embryos in culture.
(d) the introduction of a foreign gene into a plant cell.
endonuclease PstI and
5. Given below is the restriction site of a restriction
the cleavage sites on DNA molecule.

5 C-T-G -C-AG3
3 G-A-C-G -T -C5'
4
Choose the option that gives the correct resultant fragments by the action
of the enzyme PstI.

(a) 5' C -T -G C-A-G 3'

3' G- A-C-G-T C5'

(b) $' C-T G-C-A -G 3'

3' G - AG - C T-C5'

(c) 5' C-T-G-C A-G 3

3' G -A -C-G T-C5'
sd) s' C -T-G-C-A G 3'

3' G A-C-G -T -CS'

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6. Secondary treatment of sewage
(a) removes the grit and large particles of organic matter.
(b) does not require aeration as it is an anaerobic proces9.
(c) involves physical processes like filtration and sedimentation.
(d) involves digestion of organic matter by the heterotrophic microbes
naturally present in the sewage.
7. Which of the following pairs of cells are diploid in the ovule of an
angiospermic
plant?
(a) Nucellus and antipodal cells
(b) Antipodal cells and egg cell
(c) Nucellus and megaspore mother cell
(d) Nucellus and primary endosperm nucleus
8. Which of the following statements, in the context of
amniocentesis, is
incorrect?
(a) It is used for pre-natal sex determination (of the foetus).
(b) It can be used for the detection of Down's syndrome.
(c) I t can be used for the detection of cleft-palate in the foetus.

(d) It is usually done when a women is 14-18weeks pregnant.

9. Which of the following examples of ecological pyramid is not correctly

matched with its shape?
Example of Ecological Pyramid Shape
(a) The pyramid of number in a grassland ecosystem Upright
The pyramid of number in a big tree ecosystem Upright
(c) The pyramid of biomass in a pond ecosystem Inverted

(d) The pyramid of energy in a grassland ecosystem Upright

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 10. The r in the equation dNd rN describing the exponential growth
of a population, is avery important parameter chosen for annensing the
impacts of any biotic or abiotic factor on population growth. Which one of
the following statements is incorrect about r?
(a) It refers to the intrinsic rate of natural inerease.

(b) Value of 'r' is equal to b-d

(c) r value for human population in 1981 in India was 0.205.

(d) For the Norway rat the 'r' is 0,016.

gland/cells with
11. Select the correct option which matches the endocrine
their hormones.
Endocrine Gland/Cells Hormone

A. Granulosa cells (i) Relaxin

B. Placenta (ii) Estrogen

C. Corpus luteum (i) hPL

D. Pituitary (iv) Oxytocin

(a) A -(i), B - (ii), C - (iii), D - (iv)

(b) A - (ii), B (ii), C -(), D -(iv)

(c) A -iv), B -(iii), C -(ii), D -)

(d) A -(iv), B -(i), C -(üi), D - (i)

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12. Alexander von Humboldt observed that withina region, species richness
increases, when the explored area is increased. but only up to a limit.
If S = Species richness, A = Area, Z = Slope of the line (regression
coeficient) and C = y-intercept, then the species area relationship on a
log scale is described by the equation
(a) log C = log S + log 2

(b) Jeg S = log C + Z log A

(c) S= CAZ

(d) Z log A = log S + log C

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 Rare true and Ris 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): A single stranded DNA or RNA labelled with a radioactive
G molecule, is called a probe.

Reason (R): A probe is used to detect mutations in HIV-infected cells.

14. Assertion (A): Restriction endonucleases cut DNA at specific sites.

growth
Reason (R): Endonucleases are found in bacteria to restrict the
of bacteriophages.

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 15. Assertion (A): Individuals with Hb^HH
genotype exhibit sickle-cell trait.
A Reason (R): HbAHH individuals appear apparently unaffected, but they
are carriers of the disease.

16. Assertion (A): A primary spermatocyte produces four functional

spermatozoa and a primary oocyte produces only one functional ovum.
B
Reason (R): Both primary spermatocyte and primary o0cyte undergo
meiosis.

SECTION - B

causing AIDS in humans.

17. (a) Name the group of viruses responsible for
Why are these viruses so named?

of HIV infection in humans, other

(b) List any two ways of transmission
than sexual contact.

18. Attempt either option A or B

they are
Hotspots occupy less than 2% of earth's land surface. Yet,
A.
priority for conservation of biodiversity. Give two reasons for this.
given

OR

'stability of a community depends on its

B. How did Tilman show that
species-richness.' Explain.

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19. Attempt either option Aor B
A The figure given beloN shows one stage in the development of microspore.
Study the figure and answer the questions that follow:

3netic

(a) Identify the labels A and B.

(b) Draw and label the next stage of development that follows.
OR

B. Some flowers selected for artificial hybridisation do not require

emasculations but bagging is essential for them. Give a reason.

20. Attempt either option A or B.

A. A woman whose father was colourblind marries a man whose mother

was colourblind. Design a cross to find out the probability of their
female child to be colourblind.

OR

B. Mendel did not explain the expression of incomplete dominance in

plants. Give an example of flower exhibiting incomplete dominance.
Name and state the law of Mendel, the genes which exhibit incomplete
dominance follow.
fraction
21. Name the type of food chains responsible for the flow of larger
Mention
of energy in an aquatic and a terrestrial ecosystem respectively.
how they begin.
one difference between the two food chains on the basis of

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 SECTION - C
22. (a) Draw aneat diagram of L.S. of an embryo of grass and label any four
parts.

(b) Why do hybrid seeds have to be produced year after year by artificial
hybridisation?
Answer
23. Oogenesis is the process of formation of a mature female gamete.
the following questions with respect to oogenesis.
ovary of a
(a) At what stage of cell division, cells remain arrested in the
female till puberty? Name these cells.
(b) What happens to this cell in the tertiary follicle?
from this cell.
Name the cells formed as a result in the tertiary follicle
on bacterial
24. In 1928, Frederick Griffith conducteda series of experiments
transformation using the bacterium causing pneumonia as illustrated
below. Answer the questions that follow:
Expt 2 Expt 3 Expt 4
Expt 1

S strain Heat-killed
R strain S strain S strain +

Iive live Heat-killed R strain live

(a) Write the scientific name of the bacterium that causes pneumonia.

(b) In which of the four experiments did the mouse die?

(c) Diferentiate between R strain and S strain of the bacterium.

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25. Explain the three different approaches used in the treatment of a person
sufering from Adenosine Deaminase (ADA) deficiency.
26. Study the diagram given below:
5 phosphate
H
H 3 hydroxyl
H
o-I

OH

Name the linkages X, Y, Z and the respectiye molecules formed by them.

27. Given below is a diagrammatic representation of immune system of the
human body.

(a) Identify X and Y' in the given diagram.

(b) Explain two major functions of the organs that you have identified.
28. (a) Give two examples of defense mechanisms that prey species of animals
have evolved against predators.
(b) Name the type of interaction seen in each of the following.
(i) Ascaris worms living in the intestine of human.
(i) Insects feeding on plant sap.
(ii) Glomus living on the roots of higher plants.
(iv) Clown fish living among the tentacles of sea anemone.

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 SECTION - D

29. The mechanism of sex determination has always been a puzzle to the
geneticists. The initial clue about the genetic/ehromosomal mechanisn
of sex determination came from the experiments carried out on insects.
During the cytological studies made on certain species of insects, it was
observed that a specific nuclear structure could be traced through out
spermatogenesis and only 50per cent of the sperms received this structure
after spermatogenesis and the other 50 per cent did not receive it.
(a) Name the scientist who made such an observation for the first time
and the structure he observed.

Attempt either subpart (b) or (c)

(b) Differentiate between male heterogamety and female heterogamety.
OR
(c) Males are heterogametic in Drosophila and grasshopper; in the former,
the number of chromosomes in males is the same as in females, but
in the latter, the males have one chromosome less than the females.
Give reason.

(a) Give an example, where females are heterogametic.

30. A large number of couples all over the world are infertile. Such infertile
couples could be assisted to have children through certain special techniques,
commonly called 'Assisted Reproductive Technologies' (ART).
(a) Give the technical term for each of the methods described below:
(i) Transfer of ovum collected from a donor into the fallopian tube
of another female. G l
(ii) An embryo is formed in the laboratory by directly injecting the
sperm into the ovum.

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 Attempt either subpart (b) or (e)
(b) Name and explain the two methods of embryo transfer following in
vitro fertilisation.fi
OR
(c) What is artificial insemination? Mention the conditions when it becomes
necessary.

(d) Name two assisted reproductive technologies, where fertilisation isin

UVO.

SECTION - E

31. Attempt either option A or B

A. Answer the following questions based on Meselson and Stahl's

experiment:

(a) Why did the scientists use 5NH,Cl and l4NH,CI as sources of
nitrogen in the culture medium for growing E.coli?

(b) Name the molecule(s) that 5N got incorporated into.

(c) How did they distinguish between lN labelled molecules from l4N
ones?

(d) Mention the significance of taking the E.coli samples at definite

time intervals for observations.

(e) Write the observations made by them from the samples taken at
the end of 20 minutes and 40 minutes respectively.

o(f) Write the conclusion drawn by them at the end of their experiment.

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 OR

R (a) Difterentate between convergent amd divergent evolution

b) Draw the dagrammatic representationof Miller'sexperinent and
labeleleetrodes,condenser, water containing organic comnpounds and
boiling water. Mention the temperature he used in his experiment
und the products he obtainod.
32. Attempt either option A or B

A. Three circular DNA molecules were incubated independently with

three different restriction enzymes, RE-1, RE-2 and RE-3 and gel
electrophoresis wascarried out to separate the DNA fragments formed
by restriction digestion.

Observe the gel showing the migration of DNAfragments cut with the
restriction endonucleases and answer the questions that follow:
Marker RE-2 RE-3
RE-1

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 (a) Write the principle responsible for the migration of DNA fragmenta
to such diferent positions in the gel.

(b) How many recognition sites for each of these restriction enzymes
were present in the DNA cut with these enzymes? Justify your
answer.

(c) How can one visualise the se parated DNA fragments and extract
them from the gel?
OR

B. (a) Name the bacterium, whose plasmid was used successfully for the
first time as a vector by Stanley Cohen and Herbert Boyer. Narne
the gene they linked to the vector to create an rDNA.

(b) How did it become poSsible to isolate the gene of interest from
the
DNA? Name the host cell into which the rDNA was introduced.
(c) Draw a diagram of E.coli cloning vector pBR322 and
label two
selectable markersin it and twO restriction sites present on each
of the marker genes labelled.

33. Attempt either option A or B

A. (a) Name the type of immunity the colostrum provides to a

newborn
baby. Write giving an example where this type of immunity should
be provided to a person.

(b) (i) What makes some viruses to cause cancer in humans?

(ii) How do benign tumours turn malignant? How does the latter
harm the human body?

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 OR

B. (a) Why is tobacoo smoking associated with rise in blood pressure and
emphysema? Explain.

(b) Aperson is suffering throm Ascariasis. Mention the pathogen causing

the disease and an organ of the body affected, three symptoms and
one mode of transmission of the disease.

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