Explain why viruses are not placed in any of the five kingdoms used to classify living organisms.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Viruses are not made of cells and therefore lack a cellular structure.
All five kingdoms are defined by organisms that are cellular.
Viruses cannot carry out life processes independently; they can only reproduce inside a host cell.
Consequently viruses are not considered living organisms and do not meet the criteria used to classify the five kingdoms.
All five kingdoms are defined by organisms that are cellular.
Viruses cannot carry out life processes independently; they can only reproduce inside a host cell.
Consequently viruses are not considered living organisms and do not meet the criteria used to classify the five kingdoms.
Examiner tips
- Use the word "cellular" to link to the kingdoms. Show the logical sequence: structure → life processes → classification. Mention that viruses are acellular and require a host for replication.
Common mistakes
- Saying viruses are alive or giving examples of viral replication without linking to cellularity. Using vague terms like "organisms" without specifying cellular nature. Omitting the point that viruses cannot reproduce independently.
Mark scheme (4 marks)
- Viruses are not made of cells / do not have a cellular structure
- All five kingdoms contain organisms that are made of cells / are cellular
- Viruses cannot carry out life processes independently / can only reproduce inside a host cell
- Therefore viruses are not considered to be living organisms / do not meet the criteria used to define living organisms used in classification
Key terms in this question
kingdoms · viruses · living organisms
Related
- All WJEC GCSE Biology (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →