AQA GCSE Combined Science: Trilogy Biology Paper 1 (Higher), 2022: Question 1

✅ Correct answers

• Both have a cell membrane
• Both have cytoplasm

Award 1 mark for each correct similarity, up to 2 marks.

💡 Key knowledge

• All cells have a cell membrane and cytoplasm.
• Bacterial cells also have other structures such as a cell wall and often plasmids.
• Animal cells have a nucleus, but bacterial cells do not.

🧠 Exam technique

• Tick only the boxes that are true for both cells.
• If you choose one correct and one incorrect box, you lose the extra mark.
• Look for the words that appear in both cell types.

❌ Common errors

• Ticking cell wall or plasmids — these are not found in animal cells.
• Ticking nucleus — bacteria do not have one.
• Missing cytoplasm because it feels too obvious; it still counts.

✅ Correct answers

Any one of:

• Fever
• Abdominal cramps
• Stomach cramps
• High temperature
• Sweating
• Chills

1 mark for one valid symptom. Do not write vomiting or diarrhoea because the question tells you not to.

💡 Key knowledge

• Food poisoning caused by bacteria can lead to symptoms such as fever and stomach pain.
• The mark scheme accepts simple symptom words if they are clear and correct.

🧠 Exam technique

• Read the instruction carefully: “Do not refer to vomiting or diarrhoea”.
• Give one clear symptom only — no need to write a list.

❌ Common errors

• Writing vomiting or diarrhoea — these are specifically excluded.
• Using vague answers like feeling unwell — too unclear for the mark scheme.

✅ Correct answer

Penicillin

1 mark for the correct name. Phonetic spelling is accepted if clearly recognisable.

💡 Key knowledge

• Penicillin was the first antibiotic developed and is a key historical example in biology.
• Antibiotics treat bacterial infections, not viral infections.

🧠 Exam technique

• If you know only one antibiotic name from GCSE, make sure it is penicillin.
• Spelling does not have to be perfect if the answer is clearly intended.

✅ Correct answer

Any one of:

• Only a few bacteria were killed so the live bacteria continued to reproduce
• There was a time delay before the antibiotic reached the bacteria
• There was a time delay before the antibiotic could kill the bacteria

1 mark for a valid explanation of the initial rise in bacteria.

💡 Key knowledge

• Antibiotics do not necessarily work instantly.
• Bacteria can keep dividing while the medicine is being absorbed or before it reaches the infection.
• The graph shows live bacteria rising after treatment starts, which means the antibiotic had not taken full effect yet.

🧠 Exam technique

• Link your explanation to the graph: the bacteria rose before falling.
• Use cause-and-effect language: “because”, “so”, “therefore”.

❌ Common errors

• Saying the bacteria were immune — bacteria are not immune; they may be resistant.
• Saying the child’s body “got used to it” without explaining the delay or survival of bacteria.
• Only describing the graph instead of explaining the biology.

✅ Correct answer

There were fewer toxins in the body than at day 0

1 mark for selecting the statement about toxins.

💡 Key knowledge

• Bacteria can produce toxins that cause symptoms.
• If the number of bacteria falls, toxin levels can also fall.
• The child can feel better even though some bacteria are still present.

🧠 Exam technique

• The question gives two facts: the child felt better, but bacteria were still present.
• The best explanation is that the infection is less severe because less toxin is being made.

❌ Common errors

• Choosing “the child had become resistant to the bacteria” — this is not the reason.
• Choosing “bacteria had become immune to the antibiotic” — incorrect wording and idea.

✅ Correct answer

To reduce or prevent resistant strains / bacteria developing

or

To reduce or prevent antibiotic resistance in bacteria

1 mark for the idea of preventing resistance.

💡 Key knowledge

• Using antibiotics when they are not needed increases the chance that resistant bacteria survive.
• Resistance means the antibiotic no longer kills the bacteria effectively.
• Minor infections may get better without antibiotics, especially if the body’s immune system can fight them.

🧠 Exam technique

• Use the word resistance or resistant strains.
• Do not just say “to stop overuse” — explain the consequence.
• One clear sentence is enough for the mark.

❌ Common errors

• Saying bacteria become immune — bacteria are not immune; they become resistant.
• Saying “because the child will get better anyway” without mentioning resistance — usually too incomplete unless clearly linked.
• Mixing up bacteria and viruses: antibiotics do not work on viruses.

✅ Correct answer

B

1 mark for identifying the white blood cell that produces antibodies.

💡 Key knowledge

• White blood cells are part of the immune system.
• Some white blood cells produce antibodies.
• In a blood diagram, white blood cells are larger and fewer than red blood cells.

🧠 Exam technique

• Use the appearance of the cell in the figure: the labelled structure is the white blood cell.
• Antibodies are made by white blood cells, not red blood cells or platelets.

❌ Common errors

• Choosing a red blood cell — red blood cells carry oxygen.
• Choosing a platelet — platelets help clot blood.

✅ Correct answer

D

1 mark for identifying the platelet.

💡 Key knowledge

• Platelets start the clotting process.
• Red blood cells are numerous and carry oxygen.
• White blood cells are larger and part of the immune response.

🧠 Exam technique

• Platelets are very small fragments in blood diagrams.
• If you are unsure, identify the tiny cell fragment rather than a large cell.

❌ Common errors

• Choosing red blood cells because they are most common.
• Choosing the white blood cell because it is larger and more noticeable.

💡 Key knowledge

• Red blood cells: pale, disc-shaped, most numerous.
• White blood cells: larger cells, fewer in number, involved in defence and antibody production.
• Platelets: tiny fragments, important in clotting.

🧠 Exam technique

• Always match the label to the function.
• For “antibodies”, think white blood cell.
• For “clotting”, think platelet.

❌ Common errors

• Thinking all blood cells do the same job.
• Confusing platelets with white blood cells because both are small compared with red blood cells.

✅ Learn these answers

• Similarities: cell membrane, cytoplasm
• Salmonella symptom: fever or stomach cramps
• First antibiotic: penicillin
• Reason bacteria may rise at first: time delay / some survive and keep reproducing
• Feeling better after 3 days: fewer toxins
• Why avoid unnecessary antibiotics: prevent resistance
• Antibodies: white blood cell B
• Clotting: platelet D