Microscope; nitrogen; yeast; bacteria (Vibrio cholerae).
- i. sugar
- ii. alcohol
- iii. hydrochloric acid
- iv. oxygen
(ii) alcohol.
- i. Sodium bicarbonate
- ii. Streptomycin
- iii. Alcohol
- iv. Yeast
(ii) Streptomycin.
- i. female Anopheles mosquito
- ii. cockroach
- iii. housefly
- iv. butterfly
(i) female Anopheles mosquito.
- i. ant
- ii. housefly
- iii. dragonfly
- iv. spider
(ii) housefly.
- i. heat
- ii. grinding
- iii. growth of yeast cells
- iv. kneading
(iii) growth of yeast cells.
- i. nitrogen fixation
- ii. moulding
- iii. fermentation
- iv. infection
(iii) fermentation.
Bacteria - causing cholera; Rhizobium - fixing nitrogen; Lactobacillus - setting curd; Yeast - baking of bread; A protozoan - causing malaria; A virus - causing AIDS.
Most microorganisms cannot be seen with the naked eye. They are seen using a microscope; some fungal growth may be viewed with a magnifying glass.
Bacteria, fungi, protozoa, algae and viruses.
Rhizobium bacteria and blue-green algae such as Nostoc and Anabaena.
Microorganisms help set curd, make bread, prepare alcohol and vinegar, and produce antibiotics and vaccines. They decompose dead plants and animals, recycle nutrients, clean organic waste and improve soil fertility. Rhizobium and blue-green algae fix nitrogen. Some microbes are also used in large-scale production of medicines, enzymes and fermented foods.
Some microorganisms cause diseases in humans, animals and plants. Examples include cholera, tuberculosis, malaria and citrus canker. Microorganisms also spoil food by producing toxic substances, changing taste and smell, and making food unsafe. Food preservation methods slow or stop their growth.
Antibiotics are medicines produced from microorganisms or made synthetically that kill or stop growth of disease-causing microbes. They must be taken only on a doctor's advice, in the correct dose and for the full prescribed course. They should not be used unnecessarily, for viral diseases, or after expiry.