CBSE Set Q Biology Sample Test Papers For Class 12th for students online
You are on questions of Section A,B,C,D
Max Marks : 70
Time allowed : 3 hrs
Question Nos. 1-8 are of very short answer type carrying 1 mark each only. Answer them in 1-20 words each.
Q1. What induces parthenocarpy in
Q2. What is the term used for the
regions of a gene which become part of mRNA and code for the different regions
of the proteins?
Q3. The venous blood in the lung has
a PCO2 of 46 mm Hg. Should the alveolar PCO2
exceed or be less than 46 mm Hg to result in diffusion of CO2
from the blood into the alveolus?
Q4. Which part of the plant leaf is
modified to form spines of Acacia and the sheath covering the leaf of Ficus
Q5. Name the enzyme that can break
and reseal one strand of DNA.
Q6. What does the J-shaped growth
curve of a population indicate?
Q7. What forms the cambial ring in a
dicot stem during the secondary growth?
Q8. Name the principal mineral anion
in the extracellular fluid.
Question Nos. 9 – 18 are short answer questions carrying 2 marks each. It is appropriate to answer them in about 20 – 30 words.
Q9. A mother with O type blood group
has conceived. The expected blood group of the foetus is B. Will there be any
problems to the mother or the foetus? If so, specify the problems?
Q10. What are the two types of
fibres of the connective tissue? Differentiate between the two.
Q11. A farmer observed drops of
water along the margins of leaves of tomato plants growing in his well-irrigated
field on a winter morning. Give reasons for this occurrence. Why had the water
drops appeared only along the leaf margins?
Q12. Give the scientific name of
modern wheat. Why is it quoted as a typical example of rapid speciation?
Q13. Name any two of cyanobacteria
and explain how they serve as main sources of bio-fertilisers.
Q14. What are the two striking
observations when different stages of embryos of different classes of
vertebrates are studied comparatively? How does this study support evolution?
Q15. (I) An animal should possess at least one out of the three possible characteristics to enable it to function as a ureotelic organism. List these characteristics.
(II) Which among the following is /
are ureotelic animals :
Whale, camel, toad, shark.
Q16. Pick out the plant with whorled
arrangement of leaves from the list given below and say why it is categorised so
Neem; Nerium; Nepenthes.
Q17. How is elongation carried on
during protein synthesis in a cell?
Q18. What category of pathogens
causes poliomyelitis? How is crippling caused in the victim of this disease? How
can this disease be prevented?
Question Nos. 19 – 27 are short answer questions carrying 3 marks each. It is appropriate to answer them in about 30 – 50 words.
Q19. To which category of cells do
B-cells and T-cells belong? How do they differ from each other with reference to
their formation and response to antigens?
Q20. How did Urey and Miller provide
the conditions of primitive earth to prove the origin of life in their
Q21. Human skin colour is believed to be controlled by at least three separate genes.What do you call this type of inheritance?
Suppose the gene are designated as A, B, and C and darkness is dominant over fairness, what shall be the genotypes of the darkest, fairest and intermediate skin colour?
What will be the total number of allele combinations in the gametes of a person heterozygous, all the three genes.
Q22. Draw a labelled diagram of the
vertical section of human heart and show the pulmonary circulation in it by
means of arrows.
Q23. Expand PEP. Where is it
produced in C4 plants? What is its role in the biosynthetic process?
Q24. What type of striated muscles
constitute the muscles of the eyeball? How is this specific type of muscle
Q25. The base sequence on one of the
strands of DNA is TACTAGGAT.
(i) Write the base sequence of its complimentary strand.
(ii) What is the distance maintained between the two consecutive paired bases in the DNA molecule?
(iii) Who contributed the base complementarity rule?
Q26. Name the parasympathetic nerve from the brain that innervates most of the visceral organs. List any four functions of this nerve.
Q27. Sometimes natural selection is
not operative if the abnormal allele is somewhat advantageous to the individual.
Explain this mechanism with a suitable example.
Question. Nos. 28 – 30 are long answer questions carrying 5 marks each. It is appropriate to answer them in about 80 – 120 words each.
Q28. What develops into a microspore
mother cell in a flower? Trace the development of the cell into a pollen grain,
which is ready for germination. Draw a labelled figure of a mature pollen grain.
Q29. What envelops the mammalian
ovum preventing the entry of sperm into it easily? How does the sperm gain the
entry eventually? What is the significance of the point of entry of the sperm?
Q30. Who demonstrated the semi
conservative replication of DNA? Explain the experiment in detail.