AQA AS Level Biology Paper 1, November 2021: Question 9
10 marks · Medium difficulty · Short Answer
Answer questions about EPO production, its biological advantage, the immune response in mice to produce anti-human EPO antibodies, the role of antibodies in an ELISA test, and ethical issues regarding monoclonal antibody production.
Practise this questionQuestion
Question text
09 Read the following passage.
Kidney cells produce a glycoprotein hormone called erythropoietin (EPO). An
EPO molecule contains 165 amino acids and approximately 50% of its mass is
carbohydrate.
EPO is transported in the blood and stimulates the bone marrow to produce
red blood cells. In this way, enough red blood cells are produced to maintain 5
the blood’s oxygen-carrying capacity.
Some athletes choose to increase their blood EPO concentration by injecting
synthetic EPO. This practice is called blood boosting and is banned in sport as
a form of drug abuse. Athletics’ authorities use a programme of drug testing to
detect athletes who have injected EPO. In this programme, an ELISA test is 10
performed on urine samples to measure the concentration of EPO in the
athlete.
Two types of monoclonal antibody are used in this ELISA test:
• anti-human EPO antibody, prepared by injecting human EPO into mice
• anti-mouse antibody, prepared by injecting anti-human EPO antibody into 15
goats. An enzyme is attached to the anti-mouse antibody.
Use the information in the passage and your own knowledge to answer the following
questions.
09.1 Kidney cells produce a glycoprotein called erythropoietin (EPO) (line 1).
Identify two organelles in kidney cells that enable the production of EPO.
[1 mark]
09.2 Explain the biological advantage to athletes of injecting synthetic EPO (lines 7−8).
[2 marks]
09.3 Describe how mice injected with human EPO produce anti-human EPO antibody
(line 14).
[3 marks]
09.4 Describe the roles of anti-human EPO antibody and anti-mouse antibody with enzyme
attached (lines 14−16) in producing a positive result for EPO in the ELISA test.
[3 marks]
Role of anti-human EPO antibody
Role of anti-mouse antibody with enzyme attached
09.5 Some people object to using monoclonal antibodies in testing programmes.
Use information in the passage to suggest why.
[1 mark]
Mark scheme
Show the mark scheme
Question Marking Guidance Mark Comments
09.1 Rough endoplasmic reticulum/ribosomes and Golgi Ignore nucleus
(apparatus/vesicles); Reject rER for rough
1 endoplasmic
reticulum.
09.2 1. More red blood cells
OR
More haemoglobin
OR
More oxygen transport; 2
2. More (aerobic) respiration/ATP produced so
exercise longer/harder
OR
Less lactic acid/less anaerobic respiration so
exercise longer/harder;
09.3 1. (Human) EPO/antigen displayed on antigen-
presenting cells/phagocytes/B cells (in mice);
2. (Specific) helper T cell stimulates B cell to 3
divide/clone;
3. Plasma cells produce/release/secrete antibody;
2. Reject enzyme
09.4 1. (Anti-human EPO antibody) attaches/binds to
attaches/binds to
EPO/antigen (in plastic well);
anti-human EPO
antibody
2. (Anti-mouse antibody) attaches/binds to anti-
human antibody;
3. Substrate is added, enzyme causes colour – LOGY – – JUNE 2021
change/product (is positive result);
09.5 Ethics of/welfare issues with using Reference to animals
mice/goats/animals; 1 must be qualified, so
ignore "use of
animals"
TOTAL 10
How to answer it
Study Guide: Erythropoietin (EPO), Protein Synthesis & ELISA Testing
What this question tests
This exam question evaluates your understanding of cell ultrastructure (protein production organelles), physiological gas exchange adaptations, the immune response in the production of antibodies, the practical application of the ELISA test mechanism, and ethical considerations surrounding animal use in biotechnology.
Organelles Involved in Glycoprotein Production
Identify two organelles in kidney cells that enable the production of EPO. [1 mark]
✅ Correct Answer
Rough endoplasmic reticulum (or ribosomes) AND Golgi apparatus (or Golgi vesicles).
💡 Key Knowledge
EPO is a glycoprotein (a protein with a carbohydrate chain attached). Ribosomes and rER synthesise the polypeptide chain via translation, while the Golgi apparatus modifies the protein (adding the carbohydrate) and packages it into vesicles for secretion.
❌ Common Errors
Students often lose this single mark by writing abbreviations like "rER" instead of fully spelling out rough endoplasmic reticulum, or incorrectly including the "nucleus". Both organelles must be stated together to secure the mark.
Biological Advantages of Synthetic EPO
Explain the biological advantage to athletes of injecting synthetic EPO. [2 marks]
✅ Correct Answer (Any 2 points)
- More red blood cells OR more haemoglobin OR more oxygen transport.
- More (aerobic) respiration / ATP produced so athletes can exercise longer or harder.
- Less lactic acid produced / less anaerobic respiration.
🧠 Exam Technique
This is a 2-mark "explain" question. You need a cause-and-effect structure: state the physiological change (more red blood cells/oxygen) linked directly to the functional outcome (more aerobic respiration / less fatigue / exercise longer).
Monoclonal Antibody Production in Mice
Describe how mice injected with human EPO produce anti-human EPO antibody. [3 marks]
✅ Correct Answers (3 sequential marking points)
- Human EPO (antigen) is displayed on antigen-presenting cells / phagocytes / B cells in mice.
- Specific helper T cells stimulate the corresponding B cells to divide / clone (clonal selection & expansion).
- Plasma cells produce, release, or secrete the specific antibodies.
💡 Key Knowledge
This assesses standard adaptive immune response steps applied to a novel scenario. Always trace the pathway from antigen presentation -> T cell helper activation -> B cell clonal expansion -> plasma cell antibody secretion.
Mechanism of the ELISA Test
Describe the roles of anti-human EPO antibody and anti-mouse antibody with enzyme attached in producing a positive result for EPO in the ELISA test. [3 marks]
✅ Correct Answers (3 marking points)
- Anti-human EPO antibody attaches/binds to the EPO antigen fixed in the plastic well.
- Anti-mouse antibody attaches/binds to the anti-human antibody (acting as the primary antibody).
- Substrate is added, and the enzyme causes a colour change, producing a positive result.
❌ Common Errors
Examiners note that candidates frequently confuse the antibody layering order. You must reject statements suggesting the enzyme attaches directly to the anti-human EPO antibody.
Ethical Considerations
Some people object to using monoclonal antibodies in testing programmes. Use information in the passage to suggest why. [1 mark]
✅ Correct Answer
Ethics or welfare issues regarding the use of mice, goats, or animals (as mentioned in the text for preparing antibodies).
🧠 Exam Technique
The question specifies: "Use information in the passage to suggest why." Look back at lines 13-16 which mention injecting mice and goats. Your answer must explicitly reference animal welfare or ethical issues involving animals to gain credit.
Topics
Biology · 3.2 Cells
Question and mark scheme from the AQA AS Level Biology examination, Paper 1, November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.