Infectious Disease (Option A1): Eduqas A Level Biology Exam Questions by Topic

EduqasInfectious DiseaseExam Questions
Written by Tom Whitburn

Disease is the first topic of Option A, Immunology and Disease, which you meet in Section B of Component 3. You answer one option only, so this page is for students taking Option A. The topic asks you to define terms such as endemic, pandemic, antigen and vector, explain the human body as a host to other organisms, describe how diseases like cholera, malaria and TB spread and are controlled, and link the way viruses reproduce to why they cause disease.

The option questions are short, so most marks here are for exact definitions and for applying them to the organism in the stem. The examiners' reports say the same things every year: learn the definitions as they appear in the specification guidance, write about the virus when the question is about a virus, and make clear which organism "it" refers to in every sentence.

I don't teach the Eduqas specification myself, so for one-to-one help I recommend Sam. He teaches Eduqas A level Biology at a top-rated sixth form college and is very popular with his students. You can ask about lessons with Sam on WhatsApp using the link at the bottom of this page.

What you need from GCSE and Year 12

Each question on this page assumes you're secure on these ideas. If any of them feels shaky, look it up before you start.

  • Pathogens include bacteria, viruses, fungi and protoctists.
  • Communicable diseases spread by direct contact, by water, through the air and by vectors.
  • The immune system recognises foreign antigens and produces antibodies.
  • Viruses have no cytoplasm or ribosomes of their own.

Key terms

These words come up in the questions and mark schemes. Examiners expect you to use them exactly.

  • Endemic: a disease always present at low levels in an area or population.
  • Epidemic: a sudden rise in cases of a disease in one area.
  • Pandemic: an epidemic that spreads worldwide, across international boundaries.
  • Vector: an organism, such as a mosquito, that carries a pathogen from one host to another.
  • Disease reservoir: a population, often without symptoms, in which a pathogen is kept going.
  • Antigen: a molecule, usually a protein, that triggers an immune response and binds to antibodies.
  • Toxin: a chemical made by a pathogen that harms its host.

What these questions cover (Eduqas OA1)

The questions test these statements from Option A (Immunology and Disease) of the Eduqas A level Biology specification (A400). Option questions are in Component 3, and you answer only one of the three options.

  • (a) the meaning of the following terms
  • (b) the human body acting as a host to other living organisms
  • (c) the following diseases in terms of
  • (d) the relationship between the pathogenicity of viruses and their mode of reproduction

How to use this page

Write your answer on paper before you open the mark scheme. Allow about 1.2 minutes per mark: the 14 questions are worth 26 marks, so about 31 minutes in total. Then mark your answer strictly against the mark scheme and read the examiners' tip underneath it. If you'd rather print the questions, download the PDF pack.

Key terms

Question 1

A level Component 3 · Autumn 2020 · Q8(a) · 1 mark

State the meaning of endemic.

Exam question: State the meaning of the word ‘endemic’.
Show the mark scheme Mark scheme: Endemic: (A disease) which is always present at low levels in an area /that occurs frequently at a predictable rate in a specific location/area or population (1)

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From the examiners' report: Learn the definition word for word: a disease always present at low levels in an area. Calling it simply a recurring disease didn't score.

Question 2

A level Component 3 · Autumn 2021 · Q7(a)(i) · 1 mark

Describe what is meant by a pandemic, using the spread of cholera.

Exam question: Describe what is meant by the term ‘pandemic’.
Show the mark scheme Mark scheme: An epidemic occurring {worldwide /crossing international boundaries/owtte} and usually affecting a large number of people. (1)

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Question 3

A level Component 3 · June 2022 · Q7(a)(i) · 1 mark

Describe what is meant by the term antigen, using flu virus proteins.

Exam question: Describe what is meant by the term antigen.
Show the mark scheme Mark scheme: A {molecule/ protein} that {causes an immune response/causes the production of antibodies/ binds to antibodies} (by the host’s immune system)

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From the examiners' report: A short, exact statement is enough: a molecule that causes an immune response or binds to antibodies. Long, roundabout descriptions often went wrong.

Question 4

A level Component 3 · June 2025 · Q7(a) · 2 marks

Define infectious disease, toxin and antigen for scarlet fever.

Exam question: Define the following terms:
Show the mark scheme Mark scheme: • Infectious disease: (a disease that) may be {passed/ transmitted/ spread} from one individual to another/ owtte • Toxin: a chemical produced by a {microorganism/ pathogen} which causes {damage/ harm} (to its host). • Antigen: Any substance which stimulates {the production of antibodies by the immune system/ immune re

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From the examiners' report: Most students defined infectious disease, but far fewer gave correct definitions of toxin and antigen. These definitions are in the specification, so learn them exactly.

Question 5

A level Component 3 · June 2018 · Q8(e)(i) · 2 marks

State what endemic means and suggest why MRSA is not a major worry for most people.

Exam question: State what is meant by the term endemic and suggest why MRSA is not a major cause for concern amongst the general population.
Show the mark scheme Mark scheme: Endemic: a disease, always present {at low levels (in an area)/ frequently at a predictable rate in a specific location/ population} (1) {Surgical patients – skin open to bacteria} / {Sick/elderly patients – low levels of immunity}/ ORA (1)

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From the examiners' report: Use the definition from the guidance notes, then link the risk to patients with open wounds or weak immune systems.

Hosts, transmission and prevention

Question 6

A level Component 3 · June 2024 · Q7(a)(i) · 1 mark · Easy

State the role of the mosquito in the life cycle of Plasmodium.

Exam question: State the role of the mosquito in the life cycle of Plasmodium.
Show the mark scheme Mark scheme: Vector

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From the examiners' report: Almost everyone knew the answer: the mosquito is a vector.

Question 7

A level Component 3 · June 2024 · Q7(b)(iv) · 3 marks

Suggest why Plasmodium sporozoites can only be grown at 37 °C and low oxygen.

Exam question: Plasmodium sporozoites can be cultured in human cells in the laboratory under very specific conditions: • 37 °C • low oxygen concentrations. Use information from Image 7.1 to suggest why Plasmodium sporozoites can only be cultured under these conditions.
Show the mark scheme Mark scheme: Any three (x1) from • Plasmodium has {evolved / adapted} to grow inside host (1) • 37 °C {is body temperature / optimum temperature for sporozoites} (1) • Plasmodium {are predominantly anaerobic / grow better at low oxygen concentrations / owtte} (1) not obligate anaerobe • Liver cells (have a high metabolic rate and s

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From the examiners' report: Use the life cycle in the stem: Plasmodium has adapted to live inside its human host, so it needs body temperature and low oxygen.

Question 8

A level Component 3 · June 2018 · Q8(a)(ii) · 2 marks

Explain how repellent, nets and avoiding stagnant water reduce the chance of Zika infection.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Exam question: Explain how the preventative methods described above would help reduce the chance of infection with Zika.
Show the mark scheme Mark scheme: (Insect repellent/loose clothing/keeping windows closed and mosquito net) prevent mosquitoes biting (1) Not feeding (Avoiding stagnant water means) avoiding areas where mosquitoes breed (1) NOT hatching

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From the examiners' report: Apply it to Zika and its mosquito: the measures stop mosquitoes biting or keep you away from where they breed. Answers about malaria didn't score.

Question 9

A level Component 3 · Autumn 2021 · Q7(a)(ii) · 1 mark

Suggest why cholera is rare in the UK without a vaccination programme.

Information from earlier in this question:

Earlier part of the same exam question, giving the information this part uses. Exam question: Suggest why cholera is now rare in the UK despite there being no vaccination programme.
Show the mark scheme Mark scheme: UK has water treatment/sewage treatment to provide uncontaminated drinking water/water supply (1)

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Question 10

A level Component 3 · June 2022 · Q7(b)(iii) · 2 marks

Explain why people with chronic illnesses and health professionals are advised to have a flu vaccine.

Exam question: Explain why people belonging to the following specific groups are advised to obtain a flu vaccination.
Show the mark scheme Mark scheme: Weaker immune system / owtte/ flu may adversely affect symptoms of other conditions/ more likely to contract flu so increase (reservoir of) viruses in community. more likely to be infected as come into contact with greater numbers of infected people/ owtte could infect more vulnerable groups (eq) of people with flu/ re

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From the examiners' report: Give a separate reason for each group: weaker immunity for the chronically ill, and contact with many infected people for health workers.

Viruses and disease

Question 11

A level Component 3 · June 2017 · Q7(d) · 2 marks · Easy

Explain why the varicella-zoster virus must enter cells of the trachea and the effect on those cells.

Exam question: Antibiotics have no effect on viruses. Chickenpox is a highly infectious airborne disease caused by the varicella-zoster virus. The virus spreads easily in the air when an infected person coughs or sneezes. Airborne viruses have antigens that can attach to the surface membrane of
Show the mark scheme Mark scheme: One from why: Needs host cell {for reproduction/ for metabolic processes}(1) Virus has no organelles/ metabolic pathways of its own (1) Uses cell metabolic pathways for reproduction (1) One from Effects: Kills the cell by {cell lysis/ production of toxic substances (1)

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From the examiners' report: Read the stem: this is a virus, yet many answers wrote about bacteria. A virus needs the host cell's metabolism to reproduce, and the cell is killed when new viruses burst out.

Question 12

A level Component 3 · June 2022 · Q7(a)(ii) · 2 marks

Explain why viruses need a host cell to reproduce and why flu causes a sore throat.

Exam question: Explain why viruses require a host cell in order to be able to reproduce and why one of the symptoms of flu is a sore throat.
Show the mark scheme Mark scheme: Do not contain {named organelles/ ribosomes} for protein synthesis/ enzymes for replication of nucleic acid (1) (sore throat) Cell {lysis/ burst} / inflammation/ {chemical factors/ histamines} involved in immune response (1)

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From the examiners' report: Say what the virus lacks (ribosomes and enzymes for protein synthesis and copying nucleic acid), then link the sore throat to cells bursting and inflammation.

Question 13

A level Component 3 · June 2022 · Q7(a)(iii) · 3 marks

Explain how Tamiflu, a neuraminidase inhibitor, could slow a flu infection.

Exam question: Explain how ‘Tamiflu’ could reduce or prevent the progress of the flu infection in patients.
Show the mark scheme Mark scheme: Neuraminidase unable to {hydrolyse/ break down} the glycoprotein (1) virus (particles) not released / virus (particles) remains attached to {host cell/glycoprotein}. (1) Could not infect other (host) cells/{antibodies/ phagocytes} better able to target virus (1)

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From the examiners' report: Follow the chain: neuraminidase can't work, so new virus particles stay stuck to the host cell and can't infect other cells.

Question 14

A level Component 3 · June 2018 · Q8(b)(i) · 3 marks · Hard

Use a diagram of Zika replication to explain why viruses are hard to treat with drugs or vaccines.

Exam question: With reference to the diagram, suggest why viruses are difficult to treat with drugs and state the challenges faced when attempting to develop a vaccine against Zika.
Show the mark scheme Mark scheme: Any three (x1) from: A. Viruses are not cellular so do not have metabolic pathways B. A vaccine would need to target {virus infected cells/ viruses directly when in tissue fluid/blood/outside cells} C. Viruses enter host cells so they avoid recognition by host immune system/drugs may not be able to get to virus D. Drug

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From the examiners' report: Name the virus and the host cell instead of writing "it" and "they". Unclear answers were the main reason marks were lost.

Where students lose marks (from Eduqas examiners' reports and mark schemes)

Each point below is followed by wording that gained marks.

  • Endemic needs "at low levels": Answers that called endemic "a recurring disease" weren't enough.

    ✔ Gains credit: "A disease which is always present at low levels in an area".

  • Pandemic means worldwide: Key details were left out of definitions.

    ✔ Gains credit: "An epidemic occurring worldwide, crossing international boundaries".

  • Toxin and antigen are definitions too: Far fewer students could define toxin and antigen than infectious disease.

    ✔ Gains credit: "Toxin: a chemical produced by a pathogen which causes harm to its host".

  • The mosquito is a vector, not a carrier: A few students called the mosquito a carrier.

    ✔ Gains credit: "Vector" (the mark scheme says NOT carrier).

  • Bite and breed, not feed and hatch: Students didn't explain that the measures stop mosquitoes biting or keep people away from breeding sites, and wrote about malaria instead of Zika.

    ✔ Gains credit: "Prevent mosquitoes biting" and "avoiding areas where mosquitoes breed".

  • A virus question needs a virus answer: Many students wrote about bacteria even though the question was about a virus.

    ✔ Gains credit: "Needs a host cell for reproduction" because "the virus has no organelles or metabolic pathways of its own".

  • Say who "it" is: Heavy use of "it" and "they" made it impossible to tell the virus from the host.

    ✔ Gains credit: "Viruses enter host cells so they avoid recognition by the host's immune system".

Download the questions

Download the PDF pack (14 questions, mark schemes at the end)

Keep practising

Questions, mark schemes and examiners' report extracts © WJEC CBAC Ltd (Eduqas).

Tom Whitburn
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