04 May 2021

1.3. Features of organisms


The largest group of classification is Kingdom. There are 5 kingdoms and they are: Animal, Plant, Fungus, Prokaryote and Protoctist.

Cells of all living organisms contain:

  • cytoplasm, cell membrane and DNA as genetic material
  • ribosomes - for protein synthesis
  • enzymes - involved in respiration

Here are all the groups of living things we will need to know! 
Attn!: Viruses are NOT true living things!

Classification of living things igcse biology

The main differences in the 5 kingdoms are:

[for more information on the kingdoms, please click here]


1. Kingdom: Animal

Please follow these links for more details on Phylum Vertebrates and Phylum Arthropods.

[There are other groups of invertebrates (Annelids, Nematodes and Molluscs) which don't seem to be listed on the 2022 syllabus, but if you're interested, please click here]

2. Kingdom: Plant
The 2 main groups we'll focus on within this kingdom are flowering plants and ferns.

A) Flowering plants
  • multicellular, with cellulose cell walls and sap vacuoles
  • roots, stems, leaves
  • sexual reproduction via seeds; asexual reproduction possible
  • 2 groups: monocotyledons and dicotyledons 

[for more on plants, click here]

B) Ferns
  • roots stems, leaves
    • stems below ground called rhizome
    • stems and leaves have sieve tubes and water-conducting cells
    • NO buds! young leaves unwind from tight coils
  • reproduction:
    • produce gametes, but NO seeds
    • gametes --> zygote --> fern plant
    • fern plant have sporangia (spore capsules) that produce single-celled spores on the lower side of the leaves

3. Kingdom: Fungus
[The syllabus doesn't really specify much for fungi, but if you're interested, check 'em out with this link]

4. Kingdom: Prokaryotes (bacteria)
[The syllabus doesn't really specify much for prokaryotes either, but feel free to check 'em out with this link]

5. Kingdom: Protoctist
The syllabus ain't showing much love for these guys either :( There's also nothing to click, which is OK because you're probably tired of clicking by now, so here are some diagrams to look at :)


Viruses are their own peculiar breed and are NOT true living things!


Key features:

  • very small (100 times smaller than bacteria)
  • no typical cell structure
  • contain a strand of DNA or RNA
  • surrounded by a protein coat called a capsid
  • only sign of life is reproduction (in host cells)
[more on viruses: click here for the o.g. post]

For more past paper questions, click here.

Phew! This was a real long section but look! you've made it to the end so congrats :)

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