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All Biology 12 papers

Class 12 · Past paper

Biology 12 past paper 2025

44 published questions in this index. The full practice view lets you work through them and track your own attempts.

11 MCQs33 written questionsPractise this paper

Question index

  1. 1

    Which hormone is primarily responsible for regulating blood glucose levels?

    MCQ1 marksannual

  2. 1

    Describe briefly the adaptation of the human body to extreme temperature.

    Part B3 marksannual

  3. 1

    Explain the **XX-XY mechanism** of sex determination in man. Why are males known to be heterogametic?

    Part C6 marksannual

  4. 2

    When you inhale, the diaphragm:

    MCQ1 marksannual

  5. 2

    What are extraembryonic membranes? Write the name and functions of any three.

    Part B3 marksannual

  6. 2

    Describe the mechanisms involved in the transport of carbon dioxide from the tissues to lungs in human blood. Also name the process. Explain what would happen if no carbonic anhydr…

    Part C6 marksannual

  7. 3

    A school of fish swims together in a coordinated manner, with each fish following the movement of the others. It is an example of:

    MCQ1 marksannual

  8. 3

    Explain briefly the mechanism of water and electrolyte balance in the human body.

    Part B3 marksannual

  9. 3

    Describe the steps involved in **gene amplification** through **PCR**. Also enlist some of its applications.

    Part C7 marksannual

  10. 4

    A couple has a child with cystic fibrosis, an autosomal recessive disorder. If both parents are carriers of the disease but do not show symptoms, what is the probability that their…

    MCQ1 marksannual

  11. 4

    Describe briefly the role of telomeres in aging.

    Part B3 marksannual

  12. 4

    What are **ecological pyramids**? Draw and explain pyramids of energy, biomass and number.

    Part C7 marksannual

  13. 5

    Which biotechnology technique is used to produce human insulin on large scale?

    MCQ1 marksannual

  14. 5

    Explain briefly the role of neural crest in embryonic development.

    Part B3 marksannual

  15. 6

    A couple has a child with sickle cell anaemia, an autosomal disorder. If one parent is a carrier and the other is normal, what is the probability that their next child will be a ca…

    Part B3 marksannual

  16. 7

    Put the following statements in proper order to describe muscle contraction: 1. Generation of action potential in the sarcolemma 2. Release of Ca²⁺ from sarcoplasmic reticulum 3. B…

    MCQ1 marksannual

  17. 7

    What is allometric growth? Give an example.

    Part B3 marksannual

  18. 7

    How is **animal society** defined? What are its benefits? Explain the concept of **Altruism** with the example of Honey bee hive.

    Part C6 marksannual

  19. 8

    A population of bacteria develops resistance to antibiotics over time. Which evolutionary mechanism is most likely responsible for this adaptation?

    MCQ1 marksannual

  20. 8

    Describe briefly the inheritance pattern of a sex influenced trait.

    Part B3 marksannual

  21. 8

    The given figure shows three types of muscles for movement in animals. Identify and compare the properties of these muscles.

    Part C6 marksannual

  22. 10

    Spermatogenesis in human male reproductive system takes place in:

    MCQ1 marksannual

  23. 10

    What is the primary role of restriction enzymes in genetic engineering?

    Part B3 marksannual

  24. 11

    During which stage of human development does puberty occur?

    MCQ1 marksannual

  25. 11

    A couple has a child with a genetic disorder caused by a mutation in a mitochondrial gene. Who is more likely to pass on the mutation to their offspring? Explain briefly.

    Part B3 marksannual

  26. 12

    Identical twins result from the fertilization of:

    MCQ1 marksannual

  27. 12

    Write three major steps involved in DNA sequencing.

    Part B3 marksannual

  28. 13

    Explain briefly the concept of Neutral selection (Genetic drift).

    Part B3 marksannual

  29. 14

    What is the purpose of vector and DNA ligase in DNA cloning?

    Part B3 marksannual

  30. 15

    Describe briefly the structure of uterus.

    Part B3 marksannual

  31. 16

    A patient is diagnosed with a genetic disorder caused by a defective gene. How can gene therapy be used to treat this disorder? Explain briefly.

    Part B3 marksannual

  32. 17

    A backcross is made when a hybrid is crossed with its:

    MCQ1 marksannual

  33. 17

    What is the primary function of the respiratory system in humans? How is it helpful for the body?

    Part B3 marksannual

  34. 18

    How might changes in gene expression contribute to cancer development?

    Part B3 marksannual

  35. 19

    What is the significance of molecular biology in supporting evolution?

    Part B3 marksannual

  36. 20

    What is the role of fallopian tubes in the female reproductive system?

    Part B3 marksannual

  37. 21

    How do microorganisms play a crucial role in sewage treatment?

    Part B3 marksannual

  38. 22

    List down the conditions required to meet the Hardy Weinberg theorem.

    Part B3 marksannual

  39. 23

    Explain briefly the difference between sensory and motor neurons.

    Part B3 marksannual

  40. 24

    What is the significance of the hypothalamus in the endocrine system?

    Part B3 marksannual

  41. 25

    Explain briefly integrated disease management.

    Part B3 marksannual

  42. 26

    Explain briefly the concept of climax community and its significance.

    Part B3 marksannual

  43. 27

    Explain briefly the concept of ozone depletion and its significance.

    Part B3 marksannual

  44. 28

    What is the role of diaphragm in respiration?

    Part B3 marksannual

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