Protists are single-celled organisms that live in water.

Protozoans are single-celled organisms.

Single-celled organisms have the most basic form in the biological world.

What is this organism?

I saw many animals at the zoo.

We took a walk in the primeval forest over the weekend.

Microorganisms are one of the basic forms of life.

I love biology.

I am majoring in biology at university.

He is a world-renowned biologist.