Practice A2.3 Viruses (HL) with authentic IB Biology exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like cell biology, genetics, and ecology. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
Paper
Level
Question 1
HLPaper 1A
The graph shows the concentrations (log10 particles/ml) of E. coli host cells (blue line) and phage particles (red line) over time during bacteriophaqe lambda infection.
Based on the trends shown, which conclusion is most strongly supported?
Question 2
HLPaper 1A
Which feature distinguishes the influenza virus shown in the image from bacteriophage lambda?
Question 3
HLPaper 1A
The diagram shows the life cycle of a virus. Which step involves the virus entering the host cell?
Question 4
HLPaper 1A
The diagram shows a virus infecting an animal cell.What is the first step in viral infection?
Question 5
HLPaper 1B
Figure shows the life cycle of the SARS-CoV-2 virus inside a human cell. The virus binds to the ACE2 receptor and hijacks host ribosomes and organelles to replicate and assemble new virions.
1.[1]
Identify the two cellular structures used by the virus for protein synthesis and virion assembly as shown in steps 3 and 8.
2.[2]
Based on the figure, describe the role of the host ribosome in the viral life cycle after the viral genome is released.
3.[2]
Suggest why SARS-CoV-2, an RNA virus, needs to undergo both RNA replication and transcription. (Refer to steps 5 and 6)
4.[2]
Using your knowledge of the immune system, explain how helper T cells assist B cells in fighting SARS-CoV-2 infection.
5.[2]
Mutations in the spike protein gene can lead to immune evasion. Use the figure and your understanding of natural selection to explain how variants of SARS-CoV-2 may become dominant in a population.
6.[1]
Identify and explain the role of one enzyme involved in processing viral polyproteins after translation. (Refer to step 4 in the figure)
7.[2]
Based on the diagram, describe how viral envelope proteins (S, M, and E) are integrated into new virions during viral assembly.
Question 6
HLPaper 1B
The figure shows the SARS-CoV-2 virus, its interaction with human cells, and the host innate immune signaling cascade.
Panel a details structural features, panel b shows viral entry via spike protein interaction with ACE2, and panel c shows the downstream interferon immune response.
1.[3]
Based on panel a, identify three structural features of SARS-CoV-2 that are typical of viruses and explain why each is important.
2.[3]
Using panel b, describe the sequence of molecular interactions that allows SARS-CoV-2 to enter host cells.
3.[3]
Explain how panel c illustrates part of the innate immune defense, including the role of interferons.
4.[2]
SARS-CoV-2 is an RNA virus. Explain why RNA viruses, such as SARS-CoV-2, influenza, or HIV, often show very rapid evolution compared to DNA-based organisms.
Question 7
HLPaper 2
1.[7]
Explain how reverse transcriptase allows retroviruses to replicate within a host cell.
Question 8
HLPaper 1A
What is the function of the viral RNA?
Question 9
HLPaper 1B
The following electron microscope image shows the structure of a virus:
Additionally, the table below compares key characteristics of viruses and living cells:
| Feature | Virus | Living Cell |
|---|---|---|
| DNA or RNA | Yes | Yes |
| Metabolism | No | Yes |
| Ability to Reproduce | Only inside host cell | Yes (independent cell division) |
| Ribosomes | No | Yes |
| Response to Antibiotics | No | Yes (for bacteria) |
1.[2]
Based on the image and data, explain why viruses are considered non-living organisms.
2.[2]
Describe one method by which viruses reproduce inside a host cell.
Question 10
HLPaper 2
1.[7]
Focusing on the effects on the host cell and the timing of viral replication, compare and contrast the lytic and lysogenic life cycles of viruses.