BIOLOGY
Paper – 1
(THEORY)
(Botany and Zoology)
Three hours and a quarter
(The first 15 minutes of the examination are for reading the paper only.
Candidates must NOT start writing during this time).
Answer all questions in Part I and five questions from Part II, choosing three questions from
Section A and two questions from Section B. All workings, including rough work, should be
done on the same sheet as, and adjacent to; the rest of the answer. The intended marks for
questions are given in brackets [ ].
--------------------------------------------------------------------------------------------------------------------PART I (40 marks)
Answer all questions.
Question 1
a) Read the following questions carefully. For each question there are four alternatives A, B, C
and D. Choose the correct alternative and write it in your answer sheet.
[5]
i) Which of the following changes in the cell sap of the guard cell is responsible for keeping the
stomata open during the day time?
A. decrease in osmotic pressure and increase in tugor pressure.
B. increase in osmotic pressure and decrease in tugor pressure.
C. increase in both osmotic pressure and tugor pressure.
D. decrease in both osmotic pressure and tugor pressure.
ii) Micronutrients are needed in very small amounts because
A. most of them are mobile in the plant.
B. most function as co-factor in enzymes.
C. most are supplied in large quantities in soil.
D. they play a minor role in the health of the plant.
iii) The correct sequence of embryogenesis in vertebrates is
A. cleavage → morula → gastrula → blastula.
B. cleavage →gastrula →morula → blastula.
C. cleavage → morula →blastula →gastrula.
D. cleavage →blastula → gastrula →morula.
iv) The following are the effects of genetic drift theory EXCEPT
A. produces adaptive changes.
B. elimination of allele/alleles.
C. fixation of new allele/alleles.
D. produces non-adaptive changes.
v) Blood capillaries are made of
A. endothelium only.
B. endothelium and muscle fibres.
C. endothelium and connective tissue.
D. endothelium, connective tissues and muscle fibre
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vi) The discovery of Emerson effect has shown the existence of
A. photorespiration.
B. photophosphorylation.
C. two distinct photochemical reactions.
D. light and dark reactions in photosynthesis.
vii) Which hormone will be deficient, if both the ovaries of a female are removed?
A. gonadotrophic
B. oestrogen
C. oxytocin
D. prolactin
viii) The dark coloured dead wood present in the central region of old trees is called:
A. Spring wood
B. Sap wood
C. Duramen
D. Alburnum
ix) The Hardy Weinberg’s equilibrium is associated with:
A. Ionic equilibrium
B. Population genetics
C. Osmotic balance
D. None of these
x) During ageing, collagen present in intercellular spaces becomes:
A. impermeable and rigid
B. permeable and elastic
C. destroyed
D. impermeable and elastic
b) Complete the following statements. Write the correct answers in your answer scripts without
copying the whole sentence.
[10×0.5 = 5]
i) The ovum undergoes repeated cleavage divisions to form a solid mass of cells
called……….
ii) The presence of the casparian strips is the characteristic feature of ………………
iii) The study of patterns of distribution of organisms in different parts of the earth is
……………………
iv) The nutrients after absorption from the digestive tract go directly to the …………..via
blood.
v) New species evolve by sudden and distinct discontinuous heritable changes
called……………
vi) In human beings……………..shows the maximum increase in weight from birth to
adulthood.
vii) When plant absorbs water from the soil, the water potential of the root cell is ..
viii) Whiptail disease in cauliflower is caused due to the deficiency of …………..
ix) Milky water of green coconut is……………....
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x) Homozygosity of a plant raised from androgenic haploid can be maintained by treating it
with………….
c) Match each item under Column A with that which is most appropriate in Column B. You
must rewrite the correct matching pairs.
[5]
Column A
Column B
(i) Banana
i. pome
(ii) mustard
ii. berry
(iii) pea
iii. nut
(iv) apple
iv. drupe
(v) Shepherd’s purse
v. capsule
(vi) Mimosa pudica
vi. sorosis
(vii) Mango
vii. syconus
(vii) Pineapple
viii. legume
(ix) Fig
ix. lomentum
(x) litchi
x. cremocarp
xi. siliqua
xii. silicula
d) Give reasons for the following.
i) Cuttings of woody stems are dipped in auxins before planting.
ii) secondary growth does not occur in monocot stems.
iii) At higher temperatures, green plants start evolving CO2 instead of O2.
iv) Growth of bones are bidirectional.
v) Cro-Magnon man is the direct ancestor of man of today.
[5]
e) Explain what would happen ifi) Transpiration exceeds the amount of water absorbed.
ii) There is over secretion of growth hormones after adolescence.
iii) A flower bud is emasculated and auxin is applied on the stigma.
iv) The cerebellum is injured.
v) Short day plants are exposed to red light followed by far red light.
[5]
f) Differentiate between the following pairs.
i) Absorption and action spectra.
ii) B cells and T cells
iii) antibodies and interferons
iv) Transition and transversion
v) Mass selection and Pure line selection.
[5]
g) Name the following.
[5]
i) The amount of water in the soil which is available to plants.
ii) A type of heart in which the cardiac movements is initiated by nerves arising from the
brain.
iii) The phenomenon of formation of more than one embryo in one seed.
iv) The process that occurs in plants when root pressure is high and transpiration is low.
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v) A wax like secretion which eliminates some lipids such as waxes and sterols from the
body.
h) Correct the following statements by changing the underlined word.
[5]
i) The development of diploid embryo sac from diploid megaspore mother cell is called
apospory.
ii) The entry of pollen tube through the micropyle into the embryo sac is called
chalazogamy.
iii) The method of producing new crop varities in which two or more plants of unlike
genetical constitution are crossed together is known as clonal selection.
iv) Vitamin D deficiency in children causes osteomalacia.
v) Pesticides used to kill rodents are called nematicides.
Part II
Section A (30 marks)
Answer any three questions
Question 2
(a) Sieve tubes in angiosperms are associated with specialized parenchyma cells. Name those
cells. How do they help sieve tube members?
[2]
(b) The epithelial cells lining the stomach of vertebrates are protected from damage by HCl.
Explain the role of stomach in the digestion of various food materials
[2]
(c) Explain the development of different types of endosperms in angiosperms.
[3]
(d) Explain the three principle types of growth and give one example each.
[3]
Question 3
a) Eagles fly slowly but continuously for a longer time while sparrows fly too fast for a shorter
time. Give the scientific reason for this difference in the nature of muscles involved.
[2]
b) Describe the mechanism involved in the opening and closing of stomata.
[3]
c) i). List three general functions of mineral elements in the life of a plant.
[1½]
ii). What is meant by essentiality of an element?
[1½]
d) Growth stimulating hormone is produced at the tip of the coleoptiles. Explain this with an
experiment.
[2]
Question 4
a) The photosynthetic rate is higher in C4 plants than in C3 plants. Explain the adaptive value
of C4 plants.
[3]
b) i). Fishes have a venous heart. Explain double circulation in human beings.
[3]
ii). What is hypophyseal portal system? What purpose does it serve?
[1]
c) i). Give four contrivances for prevention of self pollination.
[2]
ii). Define double fertilization.
[1]
Question 5
a) Fertilization is a physico-chemical process. Describe the events that take place from the time
of entry of human sperm into the ovum till fertilization is complete.
[3]
b) I). How does the body defend itself from microorganisms and other harmful substances that
enter the airway during the breathing process?
[2]
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ii). What is the chemical equation for the formation of bicarbonate from carbon dioxide and
water? What enzyme catalyzes this reaction?
[2]
c) What causes the bending of stems and roots in tropisms? Give an example.
[2]
d) You have been asked to suggest a flowering plant that would bloom and
beautify a
lighted parking lot. The parking lot is only dark between midnight and sunrise. What
information should you research about the plants you consider? Explain your answer.
[1]
Question 6
a) Why is the cerebellum more developed in mammals that jump or fly?
[1]
b) i). What are the two main ions that participate in electrical impulse transmission in neurons?
[1]
ii). Explain the transmission of impulse across the synapse.
[3]
c) i). How is urea formed in the human body?
[2]
ii). What is tubular secretion? What are some examples of substances secreted through the
renal tubules?
[3]
Section B (30 marks)
Answer any two questions
Question 7
a) Did the earth's primitive atmosphere contain molecular oxygen? How has that molecule
become abundant?
[2]
b) How did the experiments of Redi and Pasteur refute the spontaneous generation hypothesis?
[3]
c) You have studied the story of pepper moths in England. Had the industries been removed,
what impact it could have on the moth population. Discuss.
[2]
d) While finalizing an alliance between his son and Dolly, Mr. Peter was curious to know what
was Dolly’s blood group. Mr. Peter was adamant in wanting to know the blood groups before
finalizing. The senior people got annoyed. Then Dolly stood up and gave the reasons.
i) Is it important to know the blood groups before planning for a pregnancy.
[1]
ii) What effect on the foetus may be expected if the father has A+ and the mother O+ blood
groups?
[1]
iii) What is the possible remedy in case of an Rh factor incompatibility between the foetus
and mother’s blood?
[1]
e) What is meant by the term biopesticide? Name and explain the mode of action of any one
biopesticide?
[3]
f) What are the various advantages of using genetic modified plants to increase the overall yield
of the crop?
[2]
Question 8
a) Many microbial pathogens enter the gut of humans along with food. What are the preventive
barriers to protect the body from such pathogens ? What type of immunity do you observe in
this case?
[3]
b) Give the full form of CT and MRI. How are they different from each other? Where are they
used?
[3]
c) On the basis of Darwin’s theory, explain why giraffe has a long neck?
[2]
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d) Joy loves to play football and was selected as captain of the school team for the district level
tournament. He also does social work. He attended a blood donation camp to donate blood
and came to know that he was HIV positive. He lost interest in games and refused to play or
study. He started counting his days. He remained absent from school for a long time. His
teacher visited his house and counseled him. Joy was back at school and also played the
tournament.
i) A person detected to be HIV positive should be isolated in the society? Do you agree?
Why/ Why not?
ii) How is AIDS not spread?
e) Explain the role of mutation in evolution.
[2]
f) Why are the wings of a bat said to be homologous to that of the wings of a bird but analogous
to the wings of an insect?
[1]
g) State the main evidences in favour of evolution.
[2]
Question 9
a) Ryan’s mother wondered why the mosquitoes were not responding to the mosquito repellent,
which she had been using for several years. Ryan asked his mother to change the brand they
were using. When it worked, she opined that the quality of the brand she had been using
might have degraded over the time. Ryan objected and explained to his mother the reality.
i) Why did the mosquitoes not respond to the repellent? Explain on the basis of Natural
Selection.
[2]
ii) Cite any two examples of natural selection, which we often come across.
[2]
b) Give two chromosomal similarities between man and apes.
[1]
c) Give an account of the Oparin Haldane Theory of Origin of life.
[3]
d) Give one significant difference between continuous and discontinuous distribution.
[1]
e) What is a vestigial organ? Give one example.
[1]
f) Write two distinctive features of Homoerectus.
[1]
g) Explain the role of bacteria in improving soil fertility
[2]
h) Describe briefly allopatric speciation and sympatric speciation.
[2]
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