Tiny living things
Microorganisms are living things that are so small we cannot see them with our eyes alone. We need a microscope to see them. Even though they are tiny, they are alive, and they live all around us: in the air, water, soil and even on our skin.
Key idea
Like all living things, microorganisms carry out life processes. They need food, they grow, they reproduce, and many need warmth and moisture to live.
Kinds of microorganisms
There are different kinds, such as bacteria, fungi (like yeast) and viruses. They need the right conditions to grow well, usually food, water and warmth. In a warm, damp place they can grow and spread very quickly, but in a cold or dry place they grow much more slowly.
Helpful and harmful
Some microorganisms are very useful. Yeast helps bread rise, and bacteria help make yogurt. But some are harmful: they can make food spoil (go bad) and can cause diseases.
Remember
- Microorganisms are too small to see without a microscope.
- They need food, water and warmth to grow.
- Keeping food in the fridge slows down spoilage.