Board Paper of Class 12-Science 2008 Biology (SET 1) - Solutions
General Instructions:
(i) All questions are compulsory.
(ii) This question paper consists of four Sections A, B, C and D. Section A contains 8 questions of one mark each, Section B is of 10 questions of two marks each, Section C is of 9 questions of three marks each and Section D is of 3 questions of five marks each.
(iii) There is no overall choice. However, an internal choice has been provided in one question of 2 marks, one question of 3 marks and two questions of 5 marks weightage. A student has to attempt only one of the alternatives in such questions.
(iv) Wherever necessary, the diagrams drawn should be neat and properly labelled.
- Question 2
When
and why do some animals such
as frogs hibernate?
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- Question 3
List
any two economically important products for humans obtained from Apis
indica.
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- Question 4
Name
the Indian variety of rice patented by an American company.
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- Question 5
What
role do
macrophages play in providing immunity to humans?
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- Question 6
Name the parts
‘A’ and ‘B’ of the transcription unit given
below.
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- Question 7
Name
the world’s most problematic aquatic weed. What is the nature
of the water body in which the weeds grow abundantly?
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- Question 8
What
is the major difference you observe in the offsprings produced by
asexual reproduction and in the progeny produced by sexual
reproduction?
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- Question 9
The
flower of brinjal is referred to as chasmogamous while that of beans
is cleistogamous. How are they different from each other?
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- Question 10
Name
the interaction in each of the following:
(a) Cuckoo
lays her eggs in the crow’s nest.
(b) Orchid grows on a mango tree.
(c) Ticks live on the skin of
dogs.
(d) Sea
anemone is often found on the shell of hermit crab.
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- Question 11
A
man with blood group A married a woman with B group. They have a son
with AB blood group and a daughter with blood group O. Work
out the cross and show the possibility of such inheritance.
OR
The
male fruit fly and female fowl are heterogametic while the female
fruit fly and the male fowl are homogametic. Why are they called
so?
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- Question 12
Why
is using tobacco in any form injurious to the health? Explain.
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- Question 13
Differentiate between a detritivore and a decomposer giving an example of each.
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- Question 14
A mother of one year old daughter wanted to space her second child. Her doctor suggested CuT. Explain its contraceptive actions.
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- Question 15
Study
the linking of DNA fragments shown above.
(i) Name
‘a’ DNA and ‘b’ DNA.
(ii) Name
the restriction enzyme that recognises this palindrome.
(iii) Name
the enzyme that can link these two DNA fragments.
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- Question 16
What
is divergent evolution? Explain taking an example of plants.
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- Question 17
Name
the blank spaces a, b, c,
and d in the table given below:
Type
of Microbe
|
Name
|
Commercial
Product
|
Fungus
|
a
|
Penicillin
|
Bacterium
|
Acetobacter
aceti
|
b
|
c
|
Aspergillus
niger
|
Citric
acid
|
Yeast
|
d
|
Ethanol
|
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- Question 18
Thermal
power plants are inevitable in an industrial and densely populated
country like ours. What harm do they do to the environment? Also
mention any precaution that could be taken to save our
environment.
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- Question 19
Draw
a labelled diagram of the microscopic structure of a human sperm.
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- Question 20
Expand
MOET. Explain the procedure of this technology in cattle improvement.
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- Question 21
One of the codons on mRNA is AUG. Draw the structure of tRNA adapter molecule for this codon. Explain the uniqueness of this tRNA.
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- Question 22
Study the population growth curves in the graph given below and answer the questions which follow:
(i) Identify the growth curves ‘a’ and ‘b’.
(ii) Which one of them is considered a more realistic one and why?
(iii) If is the equation of the logistic growth curve, what does K stand for?
(iv) What is symbolised by N?
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- Question 23
How and why is the bacterium Thermus aquaticus employed in recombinant DNA technology? Explain.
OR
(a) What are ‘molecular scissors’? Give one example.
(b) Explain their role in recombinant DNA technology.
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- Question 24
Given below is a part of the template strand of a structural gene:
-
(a) Write its transcribed mRNA strand with its polarity.
(b) Explain the mechanism involved in initiation of transcription of this strand.
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- Question 25
(i) How and at what stage does Plasmodium enter into a human body?
(ii) With the help of a flow-chart only, show the stages of asexual reproduction in the life-cycle of the parasite in the infected human.
(iii) Why does the victim show symptoms of high fever?
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- Question 26
It has been recorded that the temperature of the earth’s atmosphere has increased by 0.6°C.
(a) What has caused this increase?
(b) Explain its consequences.
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- Question 27
Explain the pattern of inheritance of haemophilia in humans. Why is the possibility of a human female becoming haemophilic extremely rare? Explain.
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- Question 28
Draw
a labelled diagram of the sectional view of a mature pollen grain in
angiosperms. Explain the functions of its different parts.
OR
Give
a schematic representation of Oogenesis
in humans. Mention the number of chromosomes at each stage. Correlate
the life phases of the individual with the stages of the process.
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- Question 29
(a) Mention the role of vectors in recombinant DNA technology. Give any two examples.
(b) With the help of diagrammatic representation only, show the steps of recombinant DNA technology.
OR
(a) What is plasmid?
(b) What is meant by ADA deficiency? How is gene therapy a solution to this problem? Why is it not a permanent cure?
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- Question 30
Explain
Hershey-Chase experiment. What was proved through this experiment?
OR
(a) A true
breeding pea plant, homozygous for inflated green pods,
is crossed with another pea plant with constricted yellow pods
(ffgg). What would be the phenotype and genotype of F1
and F2
generations? Give the phenotype ratio of F2
generation.
(b) State the
generalisation proposed by Mendel on the basis of the above mentioned
cross.
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