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Viruses

Characteristics and classification of living organisms · Features of organisms · note 1 of 1

Spec B10.1.5
Supplement (what this means)Supplement: only for the Extended papers (2 and 4). Core students can skip it. What the labels mean
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VirusesSpec B10.1.5

In short

A virus is a particle much smaller than a bacterium that is not made of cells, so it does not fit into the five kingdoms. Its features are limited to two: a protein coat, which surrounds and protects the genetic material, and the genetic material inside it, which carries the instructions for making new viruses.

A virus is much smaller than a bacterium. Viruses are not made of cells, so they do not fit into the five kingdoms. The features of a virus are limited to two: a protein coat and genetic material.

Features of a virus
PartDescription
Protein coatSurrounds and protects the genetic material
Genetic materialCarries the instructions for making new viruses; inside the protein coat
A virus particle in cross-section: a protein coat surrounding a strand of genetic material, with a note that there is no nucleus, no cytoplasm and no cell membrane. (opens full size in a new tab)
A virus has only a protein coat and genetic material.
Exam tip:

Do not describe a virus as having a nucleus, cytoplasm or cell membrane. State protein coat and genetic material, and nothing else.

Quick check

  1. Supplement State the two features of a virus.

    Show answer

    A protein coat and genetic material.

Written and checked against the Cambridge IGCSE Combined Science (0653) specification · Updated October 2026

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