Kingdom Plantae and Kingdom Animalia

The two big kingdoms

You know the plants and the animals better than any other organisms. In the five kingdoms they are two of five. Here we state the features that put an organism in each.

Kingdom Plantae

Plantae holds all the eukaryotic organisms that have chlorophyll: the algae, the bryophytes (mosses), the pteridophytes (ferns), the gymnosperms and the angiosperms. We study each group in the next chapter.

• The cell wall is made of cellulose.
• They make food by photosynthesis, so most are autotrophic.
• A few are partly heterotrophic. The insectivorous plants (bladderwort and the Venus fly trap) catch insects, and Cuscuta is a parasite.
• The body has tissues and organs.
• The life cycle has two phases: a diploid sporophytic phase and a haploid gametophytic phase, which follow each other. This is alternation of generations. The length of each phase, and whether it lives on its own, differ among the plant groups.

You should find that the number halves at meiosis, when the sporophyte makes spores, and doubles again at fertilisation, when two gametes make a zygote.

Kingdom Animalia

Animalia holds the heterotrophic eukaryotes that are multicellular.

• There is no cell wall.
• They depend on plants for food, directly or indirectly.
• The nutrition is holozoic: they take in food and digest it in an internal cavity.
• They store reserve food as glycogen or fat.
• Growth follows a definite pattern, and the body has organ systems. Higher forms have an elaborate sensory and neuromotor system.
• Most can move from place to place.
• They reproduce mostly sexually: a male and a female mate, and the young develop as an embryo.

Side by side

Try it in Python

This program puts the two kingdoms side by side, and finds where they agree and where they differ.

Practise with new numbers

Common mistakes

• Putting the Venus fly trap with the animals. It catches insects, but it has chlorophyll and a cellulose wall.
• Giving animals a cell wall. Animal cells have none.
• Storing starch in animals. Animals store glycogen or fat.
• Thinking the sporophyte is haploid. The sporophyte is diploid ($2n$); the gametophyte is haploid ($n$).

Remember these

• Plantae: eukaryotic, chlorophyll, a cell wall of cellulose, mostly autotrophic, alternation of generations.
• Some plants are partly heterotrophic: bladderwort, Venus fly trap, Cuscuta.
• Animalia: multicellular heterotrophs with no cell wall, holozoic nutrition, reserve food as glycogen or fat.
• Most animals can move, and most reproduce sexually.

Check yourself

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

1. Name one plant that is a parasite.

2. What does holozoic mean?

3. In which kingdom do the cells have no cell wall?

4. What is alternation of generations?