AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
Antibiotics and painkillers: Antibiotics cannot kill viral pathogens.
Viruses are not cells; they are tiny particles that reproduce only inside host cells.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 6 of 8
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Viruses are not cells; they are tiny particles that reproduce only inside host cells. They have no cell wall, no bacterial ribosomes and no other bacterial structures for an antibiotic to target, so antibiotics cannot kill them. A virus such as influenza or measles enters a host cell and uses the cell's machinery to make new virus particles. Because the virus is inside human cells, a medicine that attacked it could also harm the host cells. Viral infections are therefore treated differently: some are prevented by vaccination, some are treated with antiviral medicines, and many are managed by rest and symptom relief while the immune system clears the virus. Antibiotics may be given only if a secondary bacterial infection develops.
What earns the marks
- Viruses are not cells and do not have the bacterial structures that antibiotics target.
- Antibiotics act on structures such as bacterial cell walls or bacterial ribosomes, which viruses lack.
- Viruses reproduce inside host cells, so medicines that attack them risk damaging host cells.
- Viral infections are prevented by vaccination or treated with antiviral medicines where available.
- Many viral infections are managed by treating symptoms while the immune system clears the pathogen.
- Antibiotics may be prescribed if a viral infection leads to a secondary bacterial infection.
Common mistakes and how to put them right
Saying antibiotics are too weak to kill viruses.
Put it right by explaining that viruses lack the structures antibiotics target.
Thinking antibiotics can prevent viral infections.
Put it right by stating that vaccination is used for prevention.
Confusing antivirals with antibiotics.
Put it right by noting that antivirals act on viruses while antibiotics act on bacteria.
Exam tips
- Compare viruses and bacteria directly, for example by stating that viruses are not cells and have no cell wall.
- Use a named viral disease such as influenza or measles to support the explanation.
- Mention that antibiotics may be needed only if a secondary bacterial infection occurs.
Try the lesson
The start of the Antibiotics and painkillers: Antibiotics cannot kill viral pathogens. lesson, made from checked teaching notes for this specification point.
Have a go first
A patient has a viral infection. Why would a doctor not prescribe antibiotics for this patient?
Listen
Viruses are not cells; they are tiny particles that reproduce only inside host cells. They have no cell wall, no bacterial ribosomes and no other bacterial structures for an antibiotic to target, so antibiotics cannot kill them. A virus such as influenza or measles enters a host cell and uses the cell's machinery to make new virus particles. Because the virus is inside human cells, a medicine that attacked it could also harm the host cells. Viral infections are therefore treated differently: some are prevented by vaccination, some are treated with antiviral medicines, and many are managed by rest and symptom relief while the immune system clears the virus. Antibiotics may be given only if a secondary bacterial infection develops. A strong answer earns marks for these points. Viruses are not cells and do not have the bacterial structures that antibiotics target. Antibiotics act on structures such as bacterial cell walls or bacterial ribosomes, which viruses lack. Viruses reproduce inside host cells, so medicines that attack them risk damaging host cells. Viral infections are prevented by vaccination or treated with antiviral medicines where available. A common slip: Saying antibiotics are too weak to kill viruses. Instead, explaining that viruses lack the structures antibiotics target. Exam tip: Compare viruses and bacteria directly, for example by stating that viruses are not cells and have no cell wall.
Key words
Say what each word means before you turn the card.
Viral structure and reproduction
Try answering aloud or in your head before turning the card.
Selective toxicity of medicines
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Vaccination and antivirals
Try answering aloud or in your head before turning the card.
Secondary bacterial infection
Try answering aloud or in your head before turning the card.
See every definition
- Viral structure and reproduction
- Viruses are not cells but tiny particles that have no cell wall, no bacterial ribosomes and no other bacterial structures, and they reproduce only inside host cells.
- Selective toxicity of medicines
- Because a virus is inside human cells, a medicine that attacked it could also harm the host cells.
- Vaccination and antivirals
- Some viral infections are prevented by vaccination and some are treated with antiviral medicines, while many are managed by rest and symptom relief.
- Secondary bacterial infection
- Antibiotics may be given only if a secondary bacterial infection develops.
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