AQA AS Level Biology Paper 1, June 2024: Question 7

6 marks · Medium difficulty · Short Answer

Complete Figure 8 to show a monoclonal antibody attached to a drug, label one structural feature, and evaluate the effectiveness of an antibody-drug complex (ADC) in treating Hodgkin lymphoma using clinical trial data.

Practise this question

Question

The image shows two exam questions labelled 07.1 and 07.2. Question 07.1 has Figure 8 featuring a box labelled 'Drug' and asks students to complete the drawing to show a monoclonal antibody attached to the drug and label one structural feature, worth 2 marks. Question 07.2 presents clinical trial information and Figure 9, which shows 100 patients with Hodgkin lymphoma treated with ADC branching into Group 1 (32 patients, all detectable traces of tumours disappeared) and Group 2 (40 patients, tumours decreased by more than half the original size for 3 months on average), asking students to evaluate the effectiveness of the ADC without using statistical tests, worth 4 marks.
Question text

07.1 A drug is delivered to diseased body cells by a monoclonal antibody. The monoclonal

antibody is attached to a drug to form an antibody–drug complex (ADC).

Figure 8

Complete Figure 8 to show a monoclonal antibody attached to the drug.

Label one structural feature of the monoclonal antibody in your drawing of the ADC.

[2 marks]

07.2 Scientists used a clinical trial to test an ADC designed to treat people diagnosed with

the cancer, Hodgkin lymphoma (HL).

In the clinical trial, the patients with HL:

• were selected at random

• had tumours of a similar size at the start of the trial

• received identical doses of the ADC.

Figure 9 shows some of the results from the clinical trial.

Figure 9

Use all the information to evaluate the effectiveness of the ADC in treating people with

HL.

Do not refer to statistical tests in your answer.

[4 marks]

Mark scheme

Show the mark scheme The mark scheme provides answers for question 07.1, accepting a Y-shaped antibody linked to a rectangle with exposed arms and a label for a feature such as a disulfide bond, antigen binding site, variable region, constant region, light chain, heavy chain, hinge region, or polypeptide for 2 marks. For question 07.2, it outlines marking points for effective ideas (e.g. tumour removed in 32 patients, reduced in 40 patients) and not effective ideas (e.g. unknown effect in 28 patients, unknown long-term effect after 3 months, no control or placebo group, small sample size) requiring at least one effective and one not effective idea for full marks.

Question Marking Guidance Mark Comments

1. ‘Y’-shaped (antibody) linked to rectangle with 1. Accept ‘Y’ shape

exposed arms of ‘Y’; with 4 chains touching

For example anywhere on the

‘constant’ region of

the antibody.

2. Disulfide bridge/bond

OR

Antigen binding site

OR

Variable region

07.1 (2 x

OR AO1)

Non variable/constant region

OR

Light chain

OR

Heavy chain

OR

Hinge region

OR

Polypeptide;

(‘Effective’ ideas) For four marks, at

least ‘one effective’

1. (ADC) removed (tumours) in 32/group 1

idea and at least one

(patients)

‘not effective’ idea

OR

Accept people for

(ADC) is (cancer) cure in 32/group 1 (patients); patients

2. (ADC) reduced (the size of tumours) in 40/group

1. Accept not

detectable or

OR

(ADC) reduced (the size of tumours) 72/group1 destroyed or digested

and group 2; for removed

2. Accept positive

(‘Not effective’ ideas) effect or is effective or

works against for

3. Unknown effect (of ADC) in 28 patients reduced

OR

(Suspect ADC) did not work in 28 patients; 4 max

07.2 (4 x

4. Unknown effect (on tumours) after 3 months

AO3)

OR

Don’t know if (tumours) continue decreasing (in

size) after 3 months

OR

Don’t know if (tumours) grow (again) after 3

months;

5. Accept a

description of

5. No (information from a) control (group of

placebo, eg

patients)

non-active drug

OR

5. Ignore fake drug for

No placebo (drug used) placebo

OR 6. Ignore references

No antibody alone (used); to gender or age or

other health issues

6. (Only) small sample size;

How to answer it

Antibody-Drug Complexes & Clinical Trial Evaluation

What this question tests

This question assesses your knowledge of monoclonal antibody structure and function (specifically antibody-drug conjugates) combined with data analysis and the critical evaluation of clinical trials. You must demonstrate AO1 recall of antibody architecture and AO3 skills in interpreting experimental data, recognizing flaws in trial design (such as lack of control groups and sample size limitations), and balancing supportive evidence against missing data.

Question 07.1 • 2 Marks

Drawing and Labeling an Antibody-Drug Complex (ADC)

✅ Correct Answer Structure

  • Drawing: A distinct 'Y'-shaped structure clearly linked or attached to the given rectangle (representing the drug).
  • Labeling: Correctly identifying one structural feature, such as the antigen-binding site, variable region, constant region, heavy chain, light chain, disulfide bridge, or hinge region.

💡 Key Knowledge

  • Monoclonal antibodies have a specific quaternary structure made of four polypeptide chains (two heavy, two light) held together by disulfide bonds.
  • The variable regions at the ends of the 'Y' form unique antigen-binding sites complementary to specific antigens on diseased cells.

🧠 Exam Technique

Keep your antibody drawing simple and schematic. A classic 'Y' shape is universally accepted. Ensure your label line points precisely to the correct structural feature (e.g., the tip of the 'Y' for the variable region/antigen-binding site).

❌ Common Errors

  • Failing to attach the antibody clearly to the drug box.
  • Vague labeling lines that point ambiguously to the whole molecule rather than a specific feature.
Mark Allocation: 2 marks total (2 x AO1). One mark for the correct 'Y'-shaped drawing linked to the drug, and one mark for a correct structural label.
Question 07.2 • 4 Marks

Evaluating Clinical Trial Effectiveness

✅ Correct Answer Breakdown

To achieve full marks (4 max), you must provide a balanced answer containing at least one 'effective' point AND at least one 'not effective / limitation' point based on the data:

  • Effective: Tumours completely disappeared in 32 patients (Group 1).
  • Effective: Tumours decreased by over half in 40 patients (Group 2) — meaning a total of 72 patients showed positive reduction.
  • Limitations: Unknown effect in the remaining 28 patients (did it fail or were they lost to follow-up?).
  • Limitations: Unknown long-term effect after 3 months (do tumours grow back?).
  • Design Flaw: No control group / no placebo used for comparison.
  • Design Flaw: Small sample size (only 100 patients total).

💡 Key Knowledge

  • Evaluating experimental data requires looking at both successes and methodological shortcomings.
  • A valid clinical trial comparison requires a control group receiving a placebo or standard treatment to isolate the drug's true effect.

🧠 Exam Technique

Read the stem constraints carefully: Do not refer to statistical tests. Split your answer into two distinct columns or paragraphs in your head: evidence supporting effectiveness vs. weaknesses in trial design or results. Ensure you hit a mix of positive and negative points to unlock the 4-mark ceiling.

❌ Common Errors

  • Giving a one-sided argument (only listing successes or only listing flaws) which caps your marks at 2.
  • Mentioning correlation/causation statistical tests like chi-squared or t-tests when explicitly forbidden by the question stem.
  • Failing to calculate or state the combined total of successful outcomes (72 patients).
Mark Allocation: 4 marks max (4 x AO3). Awarded for balanced evaluation points covering both positive outcomes and critical trial limitations.

Topics

Biology · Practical skills · 3.2 Cells · Data analysis

Question and mark scheme from the AQA AS Level Biology examination, Paper 1, June 2024. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.