List of top Biology Questions asked in CBSE CLASS XII

What are the suggested reasons for population explosion?
Do you think that reproductive health in our country has improved in the past 50 years? If yes mention some such areas of improvement.
Explain the role of tapetum in the formation pollen-grain wall.
What is meant by emasculation? When and why does a plant breeder employ this technique?
Besides better aeration and mixing properties, what other advantages do stirred tank bioreactors have over shake flasks?
Do eukaryotic cells have restriction endonucleases? Justify your answer.
What would be the molar concentration of human DNA in a human cell? Consult your teacher.
From what you have learnt, can you tell whether enzymes are bigger or DNA is bigger in molecular size? How did you know?
Can you list 10 recombinant proteins which are used in medical practice? Find out where they are used as therapeutics (Use the internet).
Identify True/False statements. Correct each false statement to make it true.
  1. Androgens are produced by Sertoli cells. (True/False)
  2. Spermatozoa get nutrition from Sertoli cells. (True/False)
  3. Leydig cells are found in ovary. (True/False)
  4. Leydig cells synthesise androgens. (True/False)
  5. Oogenesis takes place in corpus luteum. (True/False)
  6. Menstrual cycle ceases during pregnancy. (True/False)
  7. Presence or absence of hymen is not a reliable indicator of virginity or sexual experience. (True/False)
Write two major functions each of testis and ovary.
Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?
What measures as an individual you would take to reduce environmental pollution?
Among the ecosystem services are control of floods and soil erosion.How is this achieved by the biotic components of the ecosystem?
What are sacred groves? What is their role in conservation?
How is biodiversity important for ecosystem functioning?
What are the major causes of species losses in a geographical region?
What is the significance of the slope of regression in a species - area relationship?
How do ecologists estimate the total number of species present in the world?
Name the three important components of biodiversity.
Write important features of a sedimentary cycle in an ecosystem.
Give an account of energy flow in an ecosystem.
Define decomposition and describe the processes and products of decomposition.
What is primary productivity? Give brief description of factors that affect primary productivity.
Describe the components of an ecosystem.