The five kingdoms

Two kingdoms were not enough

For a long time, there were only two kingdoms: plants and animals. But some living things do not fit. A mushroom grows from the soil, but it has no green colour. A bacterium is a single cell, with no nucleus. In 1969, the American scientist R. H. Whittaker gave a system of five kingdoms. It is still the system that we use most in school.

The five kingdoms are Monera, Protista, Fungi, Plantae and Animalia.

Monera

• Cells with no true nucleus. They are prokaryotes. Most have a cell wall.
• One cell.
• Some make their own food (the blue-green algae, or cyanobacteria), and some get food from others.
• Examples: bacteria and blue-green algae.

Protista

• A true nucleus. They are eukaryotes.
• One cell. Many move by cilia or flagella.
• Some make food, and some feed on other living things.
• Examples: Amoeba, Paramecium and Euglena.

Fungi

• A true nucleus and a cell wall. The wall is made of chitin.
• Most have many cells. Yeast has one cell.
• They cannot make food. They feed on dead and rotting matter, so they are heterotrophs, called saprophytes.
• Examples: yeast, mushroom and Penicillium.

Plantae

• Many cells, with a true nucleus and a cell wall of cellulose.
• They have chlorophyll, and they make food by photosynthesis. They are autotrophs.
• Examples: grass, mango tree, fern and moss.

Animalia

• Many cells, with a true nucleus and no cell wall.
• They cannot make food. They get food from other living things, so they are heterotrophs.
• Most can move.
• Examples: fish, bird, insect and human.

You should find that a nucleus, a wall and no food made point to the Fungi, with one cell or many. Take the nucleus away, and every choice gives Monera.

A few living things are exceptions. This is a simple key, and real biology has more detail.

Try it in Python

This program is a small key. It names the kingdom from four clues.

Practise with new numbers

Common mistakes

• Calling a mushroom a plant. It has no chlorophyll, and its wall is made of chitin. It is a fungus.
• Putting yeast with the Protista. Yeast has one cell, but it has a wall and feeds on sugar like other fungi.
• Thinking every one-celled living thing is a bacterium. Amoeba has a true nucleus, so it is a protist.
• Forgetting the blue-green algae. They make food, but they have no true nucleus, so they are Monera.

Remember these

• Whittaker (1969): five kingdoms, Monera, Protista, Fungi, Plantae, Animalia.
• Monera has no true nucleus. Protista has one cell with a nucleus.
• Fungi have a wall of chitin and feed on dead matter.
• Plantae make their own food. Animalia get food from others and have no cell wall.

Check yourself

Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.

1. Which kingdom has cells with no true nucleus?

2. Is a mushroom a plant?

3. What features separate Animalia from Plantae?

4. Euglena has one cell with a nucleus, no wall, and it makes its own food. Which kingdom does it belong to?