1. Living World and Classification of Microbes

Microbes are classified on the basis of the complexity of cell structure.

• Prokaryotic microbes: They have no distinct nucleus and no cell organelles. Example: Bacteria.
• Eukaryotic microbes: They have a well-defined nucleus and cell organelles. Examples: Protozoa, fungi and algae.

Lactobacilli are useful bacteria. They convert milk into curd.

The cell wall of fungi is made of a complex sugar called chitin.

Amoeba moves with the help of pseudopodia (false feet).

Tomato wilt is caused by a virus.

1. It uses many criteria like cell structure, body structure, mode of nutrition and life style.
2. Prokaryotes are kept separately in kingdom Monera.
3. All unicellular eukaryotes are kept together in kingdom Protista.
4. Fungi get a separate kingdom. They are not grouped with plants.
5. It shows the evolution of living things from simple to complex.

1. Viruses are very minute. They can be seen only with an electron microscope.
2. A virus is a DNA or RNA molecule covered by a protein coat.
3. They are not cells.
4. They multiply only inside living cells of plants, animals or bacteria.
5. Outside a living cell, they show no sign of life.
6. They cause diseases like polio, influenza and AIDS.

1. Fungi do not have chlorophyll. So they cannot make their own food.
2. Most fungi grow on dead and decaying organic matter. They are saprophytes.
3. They release digestive substances on the food and absorb the dissolved nutrients.
4. Some fungi are parasites. They take food from living hosts.

All bacteria and blue-green algae are included in kingdom Monera. They are unicellular and prokaryotic.

Examples: Lactobacillus, Salmonella typhi, Nostoc.

Viruses < Bacteria < Fungi < Algae