One cell does it all
A single cell can be a whole living organism.
A living thing with one cell
Your body has many kinds of cell, each with its own job. But an Amoeba is made of just one cell. It still has to do everything a living thing needs to do to survive.
How many cells does an Amoeba use for all its life functions?
What this lesson covers
The idea
Unicellular (single-celled) organisms such as bacteria and protozoa carry out all the functions necessary for survival within a single cell; fungi and algae may be unicellular or multicellular.
A living thing with one cell
Your body has many kinds of cell, each with its own job. But an Amoeba is made of just one cell. It still has to do everything a living thing needs to do to survive.
How many cells does an Amoeba use for all its life functions?
- Just one
- Thousands, like a human
- None
One cell or many?
Sort each living thing: unicellular (one cell) or multicellular (many cells).
Everything in one cell
Unicellular (single-celled) organisms such as bacteria and protozoa carry out all the functions necessary for survival within a single cell. Fungi and algae may be unicellular or multicellular.
- Living thing | Number of cells
- Bacteria, protozoa | One (unicellular)
- Fungi, algae | One or more: yeast is unicellular, mould is multicellular
- Plants, animals | Many (multicellular)
Notes
Unicellular organisms such as bacteria and protozoa do all the functions needed for survival in a single cell. Fungi and algae may be unicellular or multicellular.
- Unicellular | Multicellular
- Bacteria, protozoa | Plants, animals
- Yeast (a fungus) | Mould (a fungus)
Check yourself
Which of these is a unicellular organism?
How does a unicellular organism carry out the functions it needs to survive?
Yeast and mould are both fungi. Which is correct?
- Amoeba — correct. Yes. Protozoa such as Amoeba are made of one cell.
- Mango tree. A mango tree is multicellular.
- Human. Humans are multicellular.
- All of them within its single cell — correct. Yes. One cell does everything.
- By using other cells in its body. It has no other cells. It is made of just one cell.
- It does not carry out any functions. It is alive, so it carries out all the functions necessary for survival.
- Yeast is unicellular and mould is multicellular — correct. Yes. Fungi may be unicellular or multicellular.
- Both are always unicellular. Fungi may be unicellular or multicellular. Mould is multicellular.
- Both are always multicellular. Yeast is a unicellular fungus.