Exam skills
What the paper asks you to do
- Apply a key to unfamiliar organisms
- Use observable features to justify classification
- Separate cellular organisms from viruses
Foundations
Classification
Recognise shared characteristics, use classification keys and explain how DNA evidence can refine biological relationships.5090 syllabus routeConcept · skill · exam language
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Your study notes
What to know
Build the topic around four anchors.
- 01Species and the binomial system
- 02Major organism groups
- 03Viruses as acellular entities
- 04Dichotomous keys and evolutionary relationships
Common mistakes
Where marks disappear
- Treating every microorganism as a bacterium
- Using habitat instead of biological characteristics
- Giving a common name when binomial nomenclature is required
Turn this topic into a clear answer.
Write your response, reveal the teaching points, and check your own reasoning.
Practise this topic’s structured questions ↗Structured practice
Answer these without looking back.
For each prompt, write the biological chain clearly enough that every mark-worthy link is visible.
- 01Construct two steps of a dichotomous key.
- 02Explain why viruses are not placed in the five kingdoms.
- 03Use two features to distinguish an arthropod group.
Continue learning
Read the connected explanation.
From capsids and envelopes to genome classes—a connected explanation of how viruses reproduce without being cells.
This independent teaching resource follows the Cambridge O Level Biology 5090 syllabus direction and is not endorsed by Cambridge International Education.