OCR A 4.1.1(a)–(d) · 15 written questions · 28 marks · about 35 minutes · marked as you go
This free quiz has 15 written exam questions on communicable diseases, pathogens and plant defences, all taken from OCR A Level Biology A papers (AS and A level, 2016 to 2025). Short answers mark themselves. For longer answers you write your answer, then tick off the OCR mark-scheme points you made, so you see exactly where the marks are. This quiz covers the first part of OCR A topic 4.1.1: the pathogens that cause disease in plants and animals, how they are transmitted, how plants defend themselves and the body's primary non-specific defences.
What the quiz covers (OCR A spec 4.1.1(a)–(d))
Pathogens (4.1.1(a)): the type of pathogen (bacterium, virus, protoctist or fungus) behind named diseases of humans, animals and plants, including potato diseases and black sigatoka, and why viruses and Plasmodium differ in the cells they use.
Transmission (4.1.1(b)): vectors and spores, how viruses get into plant cells, how a pathogen's effect on host behaviour spreads it, and how climate change can increase vector-borne disease.
Plant defences (4.1.1(c)): the cell wall as a barrier, destroying viral RNA, plant responses to infection and where callose is deposited to stop a pathogen spreading.
Primary non-specific defences (4.1.1(d)): how mucous membranes and cilia keep viruses out, and which cells and structures prevent entry or act as physical barriers.
How to use it
Write every answer in full, as you would in the exam: the mark for each question is shown, so you know how much to write. When you self-mark, only tick a point if your answer clearly makes it, then read the examiner's tip under each question. Your progress is saved on your device, so you can do it in two sittings, and at the end you can retry just the questions where you dropped marks.
Prefer multiple choice? Try the 28-question Communicable Diseases and Immunity multiple choice quiz first.
Open the Communicable Diseases, Pathogens and Plant Defences quiz in a new tab (easier on a phone)
Where students lose marks (from OCR examiners' reports and mark schemes)
Each point below is followed by wording that gained marks.
Late blight is a protoctist: Many students said potato late blight is caused by a fungus, so the pathogen mark was lost.
✔ Gains credit: Potato (late) blight is caused by a protoctist; ring rot is caused by a bacterium.
Black sigatoka is a fungus: The most common error in the pathogen table was mixing up Protoctista and Fungi for black sigatoka in bananas.
✔ Gains credit: Black sigatoka: fungus. Malaria: protoctist. Influenza: virus. One answer per disease.
Mucus traps, not the membrane: Saying 'the mucous membranes trap the pathogen' did not score, because it is the mucus itself that does the trapping.
✔ Gains credit: Mucus traps the virus, and cilia waft the mucus away from the lungs.
Sieve pores, not sieve plates: Very few students named the gaps between sieve tube elements correctly; many wrote 'sieve plates'.
✔ Gains credit: Callose is deposited in the sieve pores (and in the plasmodesmata).
A cell wall, not skin: Asked for a barrier that stops a virus entering a plant cell, some students wrote 'skin', which OCR did not allow.
✔ Gains credit: The (cellulose) cell wall.
Think at the level of the cell: Answers such as 'through the roots' or 'through stomata' described organs and tissues when the question was about entry into a single cell.
✔ Gains credit: Through damage or a wound, or carried in by an insect vector such as an aphid.
Add a deduction to the stem: Repeating the information given ('the cells recognise and destroy mRNA') did not score: you have to apply it.
✔ Gains credit: The viral RNA is recognised as different from the cell's own mRNA, so the viral RNA is destroyed and replication stops.
Stay with the host in the question: For the zombie-ant fungus, many wrote about the infection spreading through the tree, when the disease affects ants.
✔ Gains credit: Climbing high disperses spores over a wide distance, so many other ants can be infected.
Keep practising
Try the Communicable Diseases and Immunity multiple choice quiz, the Cloning and Biotechnology multiple choice quiz, the Transport in Plants written quiz or the The Immune System, Vaccines and Antibiotics written quiz, or browse all our OCR A Level Biology quizzes. Our OCR A masterclasses (Year 12 on Wednesdays at 5.15pm, Year 13 on Tuesdays at 6.30pm) work through real exam questions on one topic each week.
Questions, mark schemes and examiners' report extracts © OCR.