Science (English Medium) Class 12 - CBSE Important Questions for Biology

Assertion (A): Decomposition process is slower if detritus is rich in lignin and cutin.

Reason (R): Decomposition is largely an oxygen requiring process.

List any four techniques where the principle of ex-situ conservation of biodiversity has been employed.

Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major vertebrate taxa.

Why should we conserve biodiversity ? How can we do it?

'in-situ' Conservation can help endangered/threatened species. Justify the statement.

Name and describe any three causes of bio-diversity losses.

Explain the concept of "co-extinction" by taking two examples.

List any three major causes of loss of biodiversity.

Enlist two criteria that are used to identify a region for maximum protection as 'Biodiversity hotspots'.

"Forests provide intangible benefits to us." Explain by taking three different areas, how.

The IUCN Red Data List (2004) in the last 500 years documents the extinction of nearly 784 species including ______.

State what is apomixis. Comment on its significance. How can it be commercially used?

Explain any three advantages that seeds offer to angiosperms.

Explain the monosporic development of the embryo sac in the ovule of an angiosperm.

Describe the role of pituitary and ovarian hormones during the menstrual cycle in a human female.

Name and explain the role of the inner and middle walls of the human uterus.

Draw a graafian follicle and label antrum and secondary oocyte.

Explain the menstruation phases in the menstrual cycle of a human female.

‘A proper understanding of the menstrual cycle can help immensely in family planning.’ Do you agree with the statement? Provide reasons for your answer.

Assertion: Functional ADA cDNA genes must be inserted in the lymphocytes at the early embryonic stage.

Reason: Cells in the embryonic stage are mortal, differentiated and easy to manipulate.