Page 61 - ACTIVE SCIENCE 4 TOC

Viruses

These are the smallest living beings. Therefore, these can
be seen under a very powerful microscope only. Viruses
can cause many diseases like chicken pox, dengue,

mumps, cold, etc.
Virus
Fungi

Fungi (sing. fungus) grow on dead or rotten matter. These
can cause skin disease like ringworms and candidiasis.
Fungi
Protozoa

Protozoa (sing. protozoan) are single-celled microbes.
These can cause diseases like dysentery and malaria.

Protozoa
Useful Microbes
Some microbes are useful in following ways:

1. Bacterium lactobacillus helps in making curd. It also helps in breaking down
of dead and decaying matter.

2. Some bacteria help in the digestion of the food we eat.

3. Some bacteria and viruses are useful in obtaining medicines.

4. Protozoa are very useful in making the soil fertile.

5. Some fungi like yeast are very useful in making the bread soft.

Let’s Recapitulate

Match the following:

1. Bacteria a. candidiasis
2. Fungi b. dysentery

3. Virus c. typhoid

4. Protozoa d. chicken pox

LET’S
REVISE

• A baby starts developing teeth at the age of six months.

• The tooth has three main parts – crown, neck and root.

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