Single-celled animals, like bacteria, consist of one cell and feed on ready-made organic matter.

Single-celled animals, like bacteria, consist of one cell and feed on ready-made organic matter. Explain why they are classified as different kingdoms of living nature.

The main difference between bacteria and unicellular animals is that bacteria lack a nucleus. For this reason, they are referred to as the Kingdom of the Nuclear-Free. Unicellular animals have an elementary nucleus and they belong to the Kingdom of Nuclear Organisms. Also, bacteria and unicellular organisms have a different reproduction process. In bacteria, recombination of the gene material occurs, and in unicellular organisms, during reproduction, the cells merge, forming gametes.