BOARD PRACTICE PAPER
Annual Exam Class - XII
DURATION: 180 Minutes M. MARKS: 70
General Instructions:
1. All questions are compulsory.
2. The question paper has five sections and 33 questions. All questions are compulsory.
3. 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.
4. 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.
5. Wherever necessary, neat, and properly labeled diagrams should be drawn.
Name of the Candidate (in Capitals): _________________________________________________________________________
Centre of Examination (in Capitals): _________________________________________________________________________
Candidate’s Signature: _______________________________ Invigilator’s Signature: _____________________________
BIOLOGY
SECTION-A 5. A person with monosomy of one sex chromosome
1. Choose the option that gives the correct number of (X-chromosome) shows:
pollen grains that will be formed after 250 A. Furrowed tongue
microspore mother cells undergo B. Rudimentary ovaries
microsporogenesis. C. Gynaecomastia
(1) 250 D. Lack of other secondary sexual characters
(2) 500 Select the correct option from the choices given
below:
(3) 1000
(1) B and D only (2) A, B and D only
(4) 750
(3) B and C only (4) A and B only
2. Plasmid is: 6. The human placenta does not secrete:
(1) linear mRNA. (1) oestrogen.
(2) circular RNA. (2) progesterone.
(3) linear DNA. (3) luteinizing hormone.
(4) circular DNA. (4) human placental lactogen.
3. How many base pairs will be there in 40 7. Which of the following is not correctly matched?
(1) Trichoderma - Effective biocontrol agent
nucleosomes in a DNA double helix?
(2) Glomus - Mycorrhiza
(1) 8000
(3) Rhizobium - Roots of leguminous plants
(2) 40
(4) Nucleopolyhedrovirus - Broad spectrum
(3) 20 insecticidal
(4) 4000 applications
4. Cocaine is obtained from _______. 8. An ideal contraceptive should not:
(1) Cannabis sativa (1) be user friendly.
(2) Erythroxylum coca (2) be irreversible.
(3) Atropa belladonna (3) be easily available.
(4) Datura (4) interfere with the sexual drive.
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9. The organism that occupies more than one trophic 14. Assertion (A): In PCR, we use Taq polymerase.
level in ecosystem is: Reason (R): Taq polymerase is a thermostable
(1) molluscs. enzyme, that remains active during the high
(2) sparrow. temperature-induced denaturation of double-
(3) lion. stranded DNA.
(4) phytoplankton. (1) Both Assertion (A) and Reason (R) are true
and Reason (R) is the correct explanation of
10. Variations are heritable and make the utilisation of the Assertion (A).
resources better for organisms that have adapted (2) Both Assertion (A) and Reason (R) are true,
the habitat better. This enables them to reproduce but Reason (R) is not the correct explanation
and leave more progeny. This was asserted by: of the Assertion (A).
(1) Charles Darwin. (3) Assertion (A) is true, but Reason (R) is false.
(2) Hugo deVries. (4) Assertion (A) is false, but Reason (R) is true.
(3) Thomas Malthus.
(4) Karl Ernst von Baer. 15. Assertion (A): Primary transcripts in eukaryotes
are subjected to splicing to remove introns.
11. The status of the human population reflected in the Reason (R): Primary transcripts in eukaryotes
human age pyramid given below is: contain both exons and introns and the introns are
non-functional in eukaryotes.
(1) Both Assertion (A) and Reason (R) are true
and Reason (R) is the correct explanation of
the Assertion (A).
(1) Declining population (2) Both Assertion (A) and Reason (R) are true,
(2) Extinct population but Reason (R) is not the correct explanation
(3) Stable population of the Assertion (A).
(4) Expanding population (3) Assertion (A) is true, but Reason (R) is false.
(4) Assertion (A) is false, but Reason (R) is true.
12. Nematode resistance tobacco plants are developed
by: 16. Assertion (A): Smoking causes a deficiency of
(1) an antibiotic. oxygen in the body.
(2) a toxic protein. Reason (R): Smoking increases carbon monoxide
(3) a DNA that produces both sense and antisense (CO) content in blood and reduces the
RNA. concentration of haembound oxygen.
(4) a particular enzyme. (1) Both Assertion (A) and Reason (R) are true
and Reason (R) is the correct explanation of
Assertion and Reason: the Assertion (A).
13. Assertion (A): Strict protection of hotspots could (2) Both Assertion (A) and Reason (R) are true,
reduce the ongoing mass extinctions by almost 30 but Reason (R) is not the correct explanation
per cent. of the Assertion (A).
Reason (R): The number of species that (3) Assertion (A) is true, but Reason (R) is false.
biodiversity hotspots collectively harbour is (4) Assertion (A) is false, but Reason (R) is true.
extremely high.
(1) Both Assertion (A) and Reason (R) are true SECTION-B
and Reason (R) is the correct explanation of 17. Differentiate between pollination in Vallisneria
the Assertion (A). and pollination in water lily.
(2) Both Assertion (A) and Reason (R) are true, (2 marks)
but Reason (R) is not the correct explanation
of the Assertion (A). 18. In which parts of the female human reproductive
(3) Assertion (A) is true, but Reason (R) is false. system are fimbriae found? Describe their role.
(4) Assertion (A) is false, but Reason (R) is true. (2 marks)
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19. Explain when is a genetic code said to be: SECTION-D
(a) Universal 29. Study the diagrammatic representation given below
(b) Degenerate (2 marks) of the Earth with regions marked ‘A’ and ‘B’
respectively. Answer the questions that follow.
20. (a) List the conditions on primitive earth that led
to the origin of life. (2 marks)
OR
(b) Mention the characteristics of reptilian eggs,
which help them to survive on land.
(2 marks)
21. How did Morgan and his group attribute the terms
‘Linkage’ and ‘recombination’ with respect to
position of genes on chromosomes. (2 marks)
SECTION-C
22. Mention the symptoms, the mode of transmission (a) Write the observation made regarding the
and name of the causal organism of the species diversity when moving from region
disease amoebiasis. (3 marks) ‘A’ to region ‘B’. Give two reasons also.
(3 mark)
23. Identify A, B, C, D, E and F in the table given below: (b) (i) Stating the reason, mention the
S. No. Organism Bioactive Use
approximate number of birds species
Molecule
1. A Penicillin B
recorded in India. (1 mark)
2. Trichoderma C D OR
polysporum (ii) Name the region in the world that records
3. E F Clot buster the greater biodiversity and mention
(3 marks) why? (1 marks)
24. Explain the evolution in relation to anthropogenic
30. Observe the diagram given below and answer the
action with the help of any two suitable examples.
(3 marks) questions that follow:
25. (a) Describe the interactions that exist between
Mediterranean orchid Ophrys and a bee
species. (2 marks)
(b) Mention the type of population interaction
shown between clown fish and sea anemone.
(1 mark)
OR
(c) Explain the following population interactions
with the help of one example each.
(i) Brood parasitism
(ii) Competition (3 marks)
26. How do contraceptive pills work? Name a non-
steroidal oral contraceptive pill. (3 Marks) (a) Mention the use of DNA ligase. (1 mark)
(b) How is the action of exonuclease different
27. (a) Explain “Rivet popper hypothesis”. from that of endonuclease?
(1.5 Marks)
(2 marks)
(b) What did David Tilman conclude from his
(c) (i) What is the purpose of sticky ends?
long-term ecosystem experiments. (1.5 marks)
(1 mark)
28. Describe the synthesis of genetically engineered OR
human insulin. (3 marks) (ii) What is EcoRI? (1 mark)
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SECTION-E (ii) How do fossils in different-aged rock
31. (a) (i) Describe any four devices which have sediments help determine the geological
been observed in plants to achieve cross period in which they existed?
pollination and discourage self- (2 marks)
pollination? (4 marks) (iii) Explain embryological support for evolution
(ii) Name the type of flowers that are that was proposed by Ernst Haeckel?
invariably autogamous. Give example of (2 marks)
plants that possess these flowers.
(1 mark) 33. (a) Differentiate between incomplete dominance
OR and co-dominance. Substantiate your answer
(b) Enumerate the events in a human female with one example each.
during: (5 marks)
(i) follicular phase. OR
(ii) menstruation phase of menstrual cycle. (b) (i) Explain how does lac operon on E.coli
(2 marks) operate in presence and absence of
inducer.
32. (a) Describe transgenic animals. Explain in detail (4 Marks)
any four areas where they can be utilised. (ii) Why does a very low level of expression
(5 marks) of lac operon has to be present in the cell
OR all the time?
(b) (i) What do you mean by term “fossil”? (1 Marks)
(1 mark)
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