Harmful Effects of Microorganisms

1. Not all bacteria are useful. Some bacteria are harmful to people.

2. Harmful microorganisms include certain bacteria, virus, fungi and protozoa. These microorganisms can cause:

(a) illnesses

(b) food poisoning

(c) food to turn bad

(d) tooth decay

3. Food poisoning is caused by eating food that is infected by harmful microorganisms.

4. Food  poisoning can lead to stomach upset, diarrhoea and vomiting.

5. Spores of microorganisms such as bacteria and fungi in the air which land on our food make food turn bad.

6. Bacteria and fungi feed on the nutrients in food and their waste products (toxin) cause food to smell and taste bad.

7. Tooth decay also caused by microorganisms.

8. Food in our mouth and on the surface of our teeth encourages the growth of bacteria. The activity of these bacteria causes tooth decay.