Mention any three ways by which potable water can be contaninated.

What is potable water ?

(a) HIV and Hepatitis-B are STDs. Mention the two other ways by which they can be transmitted to a healthy person. (b) Why is early detection of STD essential? What can it lead to otherwise? Explain.

Mention any three causes of soil pollution.

Mention three ways each by which bacteria and fungi cause harm to the environment.

Mention any three uses of optical fibres.

Mention the major cause of air pollution in metro cities. Write any three ways by which it can be reduced.

State any two ways by which food can be preserved.

Why is making cells competent essential for biotechnology experiments? List any two ways by which this can be achieved.