A Levels Biology (9700)•9700/13/M/J/25

Explanation
Virus Envelope and Capsid Identification
Steps:
- Identify label 1 as the outer protein shell enclosing viral genetic material, known as the capsid.
- Identify label 2 as the surrounding membrane layer derived from host cell lipids.
- Match descriptions: capsid is protein-based, while the envelope consists of phospholipids.
- Confirm A aligns with standard enveloped virus anatomy.
Why A is correct:
- In enveloped viruses, the capsid (1) is a protein structure protecting the genome, and the envelope (2) forms from host-derived phospholipids per virology definitions.
Why the others are wrong:
- B: Reverses the components; capsid is protein, not phospholipids.
- C: Incorrectly describes capsid as phospholipid-based, which contradicts its protein composition.
- D: Misattributes protein origin to the envelope (2), which is lipid-derived.
Final answer: A
Topic: Infectious diseases
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