Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Biology

The present population growth rate in India is alarming. Suggest ways to check it.

What is the significance of progesterone-estrogen combination as a contraceptive measure?

Mention two advantages of lactational amenorrhea as a contraceptive method.

Copper ions-releasing IUDs are more efficient than non-medicated methods. Why?

What are the advantages of natural methods of contraception over artificial methods?

Comment on the essential features required for an ideal contraceptive.

All reproductive tract infections RTIs are STDs, but all STDs are not RTIs. Justify with example.

Discuss the mode of action and advantages/disadvantages of hormonal contraceptives.

What is the function of histones in DNA packaging?

Distinguish between heterochromatin and euchromatin. Which of the two is transcriptionally active?

In an experiment, DNA is treated with a compound which tends to place itself amongst the stacks of nitrogenous base pairs. As a result of which, the distance between two consecutive base increases, from 0.34nm to 0.44 nm. Calculate the length of DNA double helix (which has 2 × 109 bp) in the presence of saturating amount of this compound.

What would happen if histones were to be mutated and made rich in acidic amino acids such as aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine?

The scientists believe that evolution is gradual. But extinction, part of evolutionary story, are 'sudden' and 'abrupt' and also group-specific. Comment whether a natural disaster can be the cause for extinction of species.

When we say "survival of the fittest", does it mean that

1. Those which are fit only survive, or
2. Those that survive are called fit

Comment.

Match the following list of bacteria and their commercially important products:

Choose the correct match:

Match the following list of bioactive substances and their roles:

Choose the correct match:

Which one of the following alcoholic drinks is produced without distillation?

What are fermentors?

Name a microbe used for statin production.

How has the discovery of antibiotics helped mankind in the field of medicine?