Question

How organisms have been classified on the basis of number of cells?

Answer 1

Cells are structural and functional units of all living organisms. All living organisms are composed of cells.On the basis of the number of cells, organisms are classified as-

• Unicellular organisms
• Multi-cellular organisms

1. Unicellular organisms are made up of a single cell. The single cell regulates all the activity of the organism. Most of the unicellular organisms are invisible to the naked eye. Examples include bacteria, protozoa, unicellular algae, and unicellular fungi.
2. Multicellular organisms are made up of more than one cell. Most of the multicellular organisms are visible to the naked eye. Organisms like plants, animals and some algae arise from a single cell and they grow up into multicellular organisms.