List of top Biology Questions asked in CBSE CLASS XII

Draw a labeled diagram of a section through ovary.
All algae have
What is oogenesis? Give a brief account of oogenesis.
Give three hypotheses for explaining why tropics show greatest levels of species richness.
Draw a labeled diagram of sperm.
Mention two strategies evolved to prevent self-pollination in flowers.
Is sex education necessary in schools? Why?
Mention any two autosomal genetic disorders with their symptoms.
Distinguish between
(a) Grazing food chain and detritus food chain
(b) Production and decomposition
(c) Upright and inverted pyramid
(d) Food chain and Food web
(e) Litter and detritus
(f) Primary and secondary productivity
What are transgenic bacteria? Illustrate using any one example.
Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because -
Draw a well-labelled diagram of an antibody molecule.
What do you think is the significance of reproductive health in a society?
What is spermatogenesis? Briefly describe the process of spermatogenesis.
Does our blood have proteases and nucleases?
If one can induce parthenocarpy through the application of growth substances which fruits would you select to induce parthenocarpy and why?
Find out from internet what is golden rice.
Describe briefly the followings:
  1. Origin of replication
  2. Bioreactors
  3. Downstream processing
Discuss with your teacher and find out how to distinguish between
  1. Plasmid DNA and chromosomal DNA
  2. RNA and DNA
  3. Exonuclease and Endonuclease
Why do you think the zygote is dormant for sometime in a fertilized ovule?
Consult internet and find out how to make orally active protein pharmaceutical. What is the major problem to be encountered?
Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and chemistry of oil?
What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his benefit?
What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
Compare and contrast the advantages and disadvantages of production of genetically modified crops.