Unit 1: Unity and Diversity
Topic 1.5: Viruses (HL) Questions
Practice 20 exam-style questions for IB Biology Topic 1.5. Review the question stems below, then unlock the full Question Bank to access markschemes, model answers, and AI grading.
1State1 mark
State the types of nucleic acid that can make up a viral genome.
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What happens to the host cell at the lysis stage of the lytic cycle?
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Which feature shows that a virus is non-cellular?
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State the term for the phage DNA once it has integrated into the host bacterium's chromosome in the lysogenic cycle.
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In the lysogenic cycle, the integrated phage DNA sitting dormant inside the host chromosome is called a:
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Which feature is unique to a temperate phage but not to a purely lytic phage?
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Reverse transcriptase catalyses the production of which molecule, and from which template?
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State the type of nucleic acid that reverse transcriptase uses as its template, and the type of nucleic acid it produces.
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2026
Draw a labelled diagram of a simple virus.
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State the term used to describe an evolutionary origin involving several separate, independent origins rather than one common ancestor.
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Which two parts are found in EVERY virus?
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State what is meant by the term lysis in the context of the lytic cycle.
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The protein capsid of a virus is built from many repeating protein sub-units.
What are these sub-units called?
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A single infected person can carry billions of virus particles, and a new generation forms in hours.
How do these two facts speed up viral evolution?
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Two different influenza strains infect one host cell and swap whole genome segments, producing a virus with almost brand-new surface proteins.
This is best described as:
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Which set of conditions is most likely to trigger induction of a prophage?
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Which row correctly contrasts the lytic and lysogenic cycles?
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Unlock Question18Outline3 marks
Outline how a virulent phage produces new copies of its genome and capsid proteins once its genome is inside the host cell.
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HIV is a retrovirus.
Outline how reverse transcriptase allows HIV to replicate inside a host cell.
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Distinguish between the action of reverse transcriptase and the action of RNA polymerase.
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