CBSE Class 12 Biology Question Paper 2008 Set 57 1

CBSE CLASS XII Questions

• 1.

  Assertion (A) : The pyramid of biomass in a pond aquatic ecosystem is always inverted.

  Reason (R) : The biomass of consumers like fishes far exceeds that of the producers like phytoplanktons.

  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  • Assertion (A) is true, but Reason (R) is false.
  • Assertion (A) is false, but Reason (R) is true.
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• 2.

  If a sperm nucleus is injected into an oocyte then all of the following events are bypassed except -

  • The swimming of sperm to meet the egg in the oviduct.
  • The sperm’s acquisition of motility in the epididymis.
  • A sperm comes in contact with the zona pellucida layer of the ovum.
  • The complex process like cell division and cell differentiation.
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• 3.

  Which of the following is a secondary consumer ?

  • Grasshopper
  • Cow
  • Fish
  • Hawk
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• 4.

  "Indo-Burma" is considered as a hotspot. What is meant by the term "hotspots" in biodiversity ? List two criteria used for determining a "hotspot". Name any two hotspots of India.

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• 5.

  Assertion (A) : The two chains of DNA have antipolarity.

  Reason (R) : In one chain of DNA, ribose sugar at \(5^{\prime}\) end consists of a free phosphate moiety, while at the other end, the ribose sugar has free \(3^{\prime}\) - OH group.

  • Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  • Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  • Assertion (A) is true, but Reason (R) is false.
  • Assertion (A) is false, but Reason (R) is true.
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• 6.

  (i) Differentiate between a DNA and RNA nucleotide.

  (ii) Name the two types of bonds present within a single nucleotide.

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