Too small to see

The idea

Living organisms made of just one or very few cells, too small to be seen with the naked eye, are microorganisms; some are unicellular and others multicellular.

The smallest organisms

Plants and animals are organisms. Some organisms are so small that you cannot see them with your eyes at all.

Is there living stuff all around us that we cannot see?

• Yes, tiny living things exist
• No, if it is alive we can see it
• Only in the sea

Is it a microorganism?

A microorganism is made of just one or very few cells and is too small to see with the naked eye. Sort each living thing.

One cell or a few

Microorganisms are living organisms made of just one or very few cells, too small to be seen with the naked eye. Some are unicellular and others multicellular.

• Kind | Examples
• Unicellular (one cell) | Bacteria, Amoeba
• Multicellular (many cells) | Some fungi and algae

Notes

Microorganisms are living organisms made of one or very few cells, too small to see with the naked eye. Some are unicellular and others multicellular.

• Unicellular | Multicellular
• Bacteria, Amoeba | Some fungi and algae

Check yourself

Which of these is a unicellular microorganism?

Why do we need a microscope to see microorganisms?

Which microorganisms are multicellular?

• Amoeba — correct. Yes. Amoeba is made of just one cell.
• Mango tree. A mango tree has many cells and is easy to see.
• Cow. A cow has very many cells and is easy to see.
• They are too small to be seen with the naked eye — correct. Yes. A microscope magnifies them so we can see them.
• They are hidden under the soil. Many are in water, soil and air, but the real reason is that they are too small.
• They are always transparent glass. Their size is the problem: they are too small for our eyes.
• Some fungi and algae — correct. Yes. Some fungi and algae have many cells.
• Bacteria and Amoeba. Bacteria and Amoeba are made of just one cell.