Fill in the blanks.

(a) Microorganisms can be seen with the help of a …………… .

(b) Blue green algae fix …………… directly from air and enhance fertility of soil.

(c) Alcohol is produced with the help of …………… .

(d) Cholera is caused by …………… .

Yeast is used in the production of

1. sugar
2. alcohol
3. hydrochloric acid
4. oxygen

Carrier of malaria-causing protozoan is

1. female Anopheles mosquito
2. cockroach
3. housefly
4. butterfly

The most common carrier of communicable diseases is

1. ant
2. housefly
3. dragonfly
4. spider