Key learning points

1. Bacteria are living organisms; each bacterium is a microorganism made of a single living cell.
2. Some bacteria are pathogens that cause diseases, but many bacteria are harmless and some are helpful.
3. Helpful bacteria live inside the human digestive system.
4. They release enzymes that digest food we cannot digest ourselves.
5. They also help to protect us against pathogens that enter the digestive system by competing against them.

Keywords

• Bacteria - Bacteria are unicellular organisms.

• Microorganism - A microorganism is an organism that can only be seen using a microscope.

• Pathogen - A pathogen is a microorganism that causes disease.

• Enzyme - An enzyme is a biological catalyst that speeds up the rate of reaction such as digestion.

• Competition - Competition occurs between living organisms, e.g. bacteria competes for food and space to live.

Common misconception