Molecular Basis of Inheritance — BIOLOGY STD 12 Science — Question

During reproduction, the chromosome number (2n) reduces to half (n) in the gametes and again resume the original number (2n) in the offspring, what are the processes through which these events take place?

What does ‘competent’ refer to in competent cells used in transformation?

How do Darwin’s finches illustrate adaptive radiation?

Name any two organisms and the phenomenon involved where the female gamete undergoes development to form new organisms without fertilisation.

When a foreign DNA is introduced into an organism, how is it maintained in the host and how is it transferred to the progeny of the organism?

A woman has certain queries as listed below, before starting with contraceptive pills. Answer them.

1. What do contraceptive pills contain and how do they act as contraceptives?
2. What schedule should be followed for taking these pills?

Offspring derived by asexual reproduction are called clones. Justify giving two reasons.

Enumerate the major causes of deforestation.

Identify A, B, C and D in the following table with reference to birth control.

Method	Example
A	Diaphragm
Female sterilisation	B
C	Saheli
D	Cu-T

How is outcrossing different from cross breeding?