Classification of living organisms: Eukaryota (which includes protists, fungi, plants and animals).

The idea

Eukaryota is one of the major taxonomic groups used in classification. Its members share a cellular feature: their cells contain a nucleus and other membrane-bound organelles, so genetic material is enclosed rather than free in the cytoplasm. The group is broad and includes protists, fungi, plants and animals, which differ greatly in nutrition, mobility and cell structure.

For example: A mushroom, an oak tree, a human and a single-celled Amoeba are all eukaryotes even though only some are multicellular.

What earns the marks

• Eukaryotic cells possess a true nucleus enclosing the genetic material.
• Eukaryotic cells also contain membrane-bound organelles such as mitochondria.
• Eukaryota includes the kingdoms of protists, fungi, plants and animals.
• Members of Eukaryota may be unicellular or multicellular, so cell number alone does not define the group.
• Classification places organisms into groups based on shared features, and the nucleus is the key shared feature here.
• Examples such as Amoeba, mushroom, oak and human can all be identified as eukaryotes.

Common mistakes and how to put them right

• Thinking all eukaryotes are multicellular.

  Put it right: Many protists are unicellular eukaryotes, so the group includes both unicellular and multicellular organisms.

• Believing bacteria belong to Eukaryota.

  Put it right: Bacteria are prokaryotes and lack a true nucleus, so they are classified separately.

• Assuming all eukaryotes photosynthesise.

  Put it right: Animals and fungi are eukaryotes that do not photosynthesise, so nutrition varies within the group.

Exam tips

• Link the name Eukaryota to the word 'eukaryotic' and state the defining feature of a nucleus.
• When asked to name kingdoms within Eukaryota, list protists, fungi, plants and animals.
• Use a named example to support your answer, such as Amoeba as a unicellular eukaryote.