AQA GCSE Biology Biology Paper 1 (Higher), 2024: Question 6

✅ Correct answer

Penicillin

The mark scheme allows penicillin or any other named antibiotic.

💡 Key knowledge

• Antibiotics are drugs used to kill bacteria or stop them growing.
• Common examples include penicillin, amoxicillin and tetracycline.

🧠 Exam technique

• You only need one named example.
• Spell it clearly and avoid writing a disease name instead of a drug.

✅ Correct answer

• The bacterium is killed by antibiotic C.
• If it were resistant, bacteria would grow right up to the edge of the disc.

You could also say there is a zone of inhibition around antibiotic C.

💡 Key knowledge

• A zone of inhibition is the clear area where bacteria do not grow.
• If bacteria grow close to the disc, the antibiotic is affecting them.
• Resistance means the bacteria are not killed by that antibiotic.

🧠 Exam technique

• To gain both marks, make two linked points:
• 1. the antibiotic does kill the bacteria, and
• 2. resistant bacteria would grow all the way to the disc.

❌ Common errors

• Saying only “there is a white space” without explaining what it means.
• Saying “the bacteria are resistant” when the diagram shows a clear inhibition zone.
• Confusing disc with the zone.

✅ Correct answer points

• Current antibiotics may not kill some bacteria.
• Diseases may become more common or harder to treat.
• New antibiotics would need to be developed, which takes time and money.

Any two valid points gain full marks.

💡 Key knowledge

• Resistance means some bacteria survive treatment.
• Those surviving bacteria can reproduce and spread.
• Eventually, some infections may become much harder to cure.

🧠 Exam technique

• This is a 2-mark explain question.
• Write two separate consequences, not just one idea repeated.
• Use phrases like harder to treat , new antibiotics needed , more common .

❌ Common errors

• Only saying “people get ill” — this is too vague.
• Talking about viruses instead of bacteria.
• Not explaining the impact on treatment.

✅ Correct answer

Viruses only exist / reproduce inside living cells.

Agar is not made of living cells, so viruses cannot reproduce on it.

💡 Key knowledge

• Viruses are not cells.
• They need a host cell to reproduce.
• Agar provides nutrients for bacteria, not the living cells viruses need.

🧠 Exam technique

• Use the key idea: viruses need living cells.
• Do not just say “they are too small” — that does not answer the question.

❌ Common errors

• Saying “viruses cannot grow because agar is solid” — not enough for the mark.
• Confusing viruses with bacteria.

✅ Correct answer

The drugs can damage body cells / tissues, or it is hard to get the drugs into living cells.

Another accepted idea is that viruses often mutate, which can make them resistant.

💡 Key knowledge

• Viruses live inside body cells, so any drug must target the virus without harming the host cell.
• This makes selective treatment difficult.
• Viruses can also mutate rapidly, creating resistance.

🧠 Exam technique

• Focus on the problem of targeting viruses inside cells.
• For 1 mark, one clear reason is enough.

❌ Common errors

• Saying “antibiotics do not work” without explaining why.
• Describing bacteria cell walls — viruses do not have these.

✅ Correct answer

AIDS

This is the only correct box to tick.

💡 Key knowledge

• AIDS is caused by HIV.
• HIV infects and damages white blood cells, weakening the immune system.

❌ Common errors

• Choosing gonorrhoea or salmonella — these are not viral diseases.
• Choosing measles because it is viral, but it does not damage white blood cells in the way described.

💡 Key answers at a glance

• 06.1: Penicillin
• 06.2: Bacteria are killed by antibiotic C; if resistant, bacteria would grow to the disc
• 06.3: Some antibiotics no longer work; diseases become harder to treat; new antibiotics take time/money
• 06.4: Viruses only reproduce inside living cells
• 06.5: Drugs may damage body cells or be hard to get into living cells
• 06.6: AIDS

🧠 How top responses score full marks

• Use exact biology terms: zone of inhibition, resistant, living cells.
• Link observation to conclusion: clear zone = antibiotic works.
• Give more than one consequence when the question asks for 2 marks.