Are there such things as single cell organisms?

Answer 1

Of course! All life on the planet began originally from single cell (or unicellular) organisms.

An example of a single cell organism would be a bacterium (e.g. E. Coli) or an amoeba.

There are many, many different types of unicellular organisms, found in all sorts of place. In the soil, underwater, one your toilet seat - even in your own body.

Using bacteria (just one of many types of unicellular organism) as an example, for every one cell in the human body, there are roughly 10 foreign unicellular organisms counting bacteria alone. And there are 500-1000 different types of bacteria just in your gut! The other main location for bacteria to be found in the body is the mouth, which is teeming with foreign unicellular organisms.

Bear in mind of course, bacteria are only one type of unicellular organism. All prokaryotes (cells that lack membrane bound organelles - as opposed to eukaryotes which do have membrane bound organelles, all human body cells are eukaryotic) most protists, and some fungi are unicellular too.

Unicellular organisms are not only important in that they were the first ever living organisms to inhabit our planet, they are hugely important for sustaining life today. Without them, the human race could not survive!