Question

In which case does a single cell constitute a whole organism?

Answer 1

Type of organisms based on cell number:

Based on cell numbers, organisms are grouped under two categories:

1. Unicellular organisms - organisms having a single cell.
2. Multicellular organisms - organisms having more than one cell or group of cells.

Unicellular organisms:

1. In several organisms, a single cell is capable of performing all the cell functions that are vital for its survival.
2. In such organisms, no division of labour is present.
3. There is no tissue or organ formation.
4. Examples - Amoeba, yeast, Chlamydomonas, etc.