Practice IB Biology Topic A2.3 Viruses with authentic exam-style questions for both SL and HL students. This question bank focuses on the exact syllabus content for A2.3 Viruses and mirrors Paper 1A, 1B, 2 style where relevant.
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Which feature distinguishes the influenza virus shown in the image from bacteriophage lambda?
Coronaviruses are enveloped RNA viruses whose surface structure is central both to how they infect cells and to how they escape the immune system.
(a) how the envelope and glycoprotein spikes of a coronavirus enable it to infect a host cell.
(b) how mutations in the gene coding for the spike glycoprotein can allow a coronavirus to evade host immunity.
(c) the replication of a coronavirus with that of HIV.
Which step in the diagram involves the virus entering the host cell?
The great diversity of viruses suggests that they may have arisen from other organisms on several separate occasions, rather than from a single common ancestor.
(a) All viruses share a small set of features, such as a protein capsid and a minimal genome. how these shared features could be the result of convergent evolution.
(c) how the diversity of viral genetic material (DNA or RNA, single- or double-stranded) supports the idea of several origins.
(d) the claim that all viruses evolved from a single common ancestor.
Four particles have the features shown.
| Particle | Nucleic acid | Protein capsid | Cytoplasm | Enzymes |
|---|---|---|---|---|
| P | DNA | present | absent | 1 |
| Q | RNA | absent | absent | 0 |
| R | RNA | present | absent | 0 |
| S | DNA | present | present | 20 |
Which particles have every feature consistent with a virus?
Presence of nucleic acid as genetic material
Presence of protein capsid surrounding the genetic material
Presence of an outer lipid membrane derived from the host cell
Use of reverse transcriptase for genome replication
(b) Consider evidence about the origins of viruses.
The genetic code is shared between viruses and living organisms. what this suggests about the origin of viruses.
