List the three methods by which fertilization of human ovum by sperm can be prevented.

Name the methods to overcome in fertility in human couples.

Name two methods by which mosquito population can be controlled to prevent malaria .

Assertion : The RNAi can be introduced in an organism by insertion of gene encoding complementary RNA only Reason : There are no methods by which in vitro synthesised complementary RNA can be inserted in an organism to induce RNAi (RNA interference)

List any two common methods by which solid wastes of urban areas are disposed off.

One of the methods by which recombinant DNA can be introduced into host cell is by 'heat shock' treatment (electro-poration). Write down other three important methods by which we can introduce alien DNA into host cells .

Mention some methods by which you can save electricity at home.

There are ten points in the plane, no three of which are coolinear. How many different lines can be drawn through these points ?