Antibiotics and Painkillers
Master Antibiotics and Painkillers for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Antibiotics kill bacteria but have no effect on viruses, while painkillers only treat the symptoms of a disease.
Free downloads
These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
Antibiotics are medicines that kill bacteria inside the body. Penicillin is the classic example, discovered by Alexander Fleming from the Penicillium mould.
The crucial limitation is that antibiotics do not work on viruses. Viruses live and reproduce inside body cells, so a drug that killed them would damage the cell too. This is why antibiotics are useless against colds and flu.
Painkillers and other medicines treat the symptoms of a disease but do not kill the pathogen. Understanding that distinction — treating symptoms versus curing the infection — is examined regularly.
Revision notes
What antibiotics do
Antibiotics kill bacteria inside the body, and specific bacteria should be treated with specific antibiotics.
The use of antibiotics has greatly reduced deaths from infectious bacterial diseases. Penicillin was discovered by Alexander Fleming from the Penicillium mould.
Why they do not work on viruses
Viruses reproduce inside the body's own cells, so it is difficult to develop drugs that destroy them without damaging the cells too.
This is why antibiotics have no effect on colds, flu or measles.
Painkillers
Painkillers and similar medicines treat the symptoms of a disease — relieving pain or reducing fever — but they do not kill the pathogen.
So a painkiller may make someone feel better without curing the infection at all.
Key points
- Antibiotics kill bacteria inside the body.
- Penicillin was discovered by Alexander Fleming.
- Antibiotics do not work on viruses.
- Viruses reproduce inside cells, making them hard to target.
- Painkillers treat symptoms, not the pathogen.
- Specific bacteria need specific antibiotics.
Worked examples
Example 1
Explain why antibiotics cannot be used to treat influenza. [2 marks]
Model answer
Influenza is caused by a virus, and antibiotics only kill bacteria (1 mark). Viruses reproduce inside the body's cells, so it is difficult to develop a drug that destroys them without also damaging the cells (1 mark).
Example 2
Explain the difference between an antibiotic and a painkiller. [2 marks]
Model answer
An antibiotic kills the bacteria causing the disease, so it treats the cause (1 mark). A painkiller only relieves the symptoms and does not kill the pathogen (1 mark).
Example 3
A patient with a bacterial infection is given an antibiotic but does not improve. Suggest one reason why. [2 marks]
Model answer
The bacteria may be a resistant strain that the antibiotic cannot kill (1 mark), or the wrong antibiotic may have been prescribed, since specific bacteria must be treated with specific antibiotics (1 mark).
Common mistakes
Saying antibiotics kill all pathogens.
They only kill bacteria. They have no effect on viruses, protists or fungi.
Saying painkillers cure infections.
They relieve symptoms only; the pathogen remains.
Not explaining why viruses are hard to treat.
The reason is that they reproduce inside the body's own cells.
Confusing antibiotics with antibodies.
Antibiotics are medicines; antibodies are proteins made by white blood cells.
Exam tips
- Always give the reason viruses are difficult to target.
- Distinguish treating symptoms from killing the pathogen.
- Name penicillin and Fleming if asked for an example.
- Mention resistance as a possible reason a treatment fails.
Key terms
- Antibiotic
- A medicine that kills bacteria inside the body.
- Painkiller
- A medicine that relieves symptoms without killing the pathogen.
- Penicillin
- The first antibiotic, discovered by Alexander Fleming.
- Resistant strain
- Bacteria that an antibiotic can no longer kill.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.