This free quiz has all 15 multiple choice questions from Section A of the OCR A Level Biology A Biological Diversity paper (H420/02), November 2020. It marks itself, so you get your score as soon as you finish.
What the multiple choice section covers
Pathogens and the diseases they cause in plants and animals (4.1.1)
Plant responses to pathogens and identifying cells in a blood smear (4.1.1)
Erythrocytes, stem cells and features of eukaryotic cells (2.1.1, 2.1.6)
Testing expected ratios in a genetic cross (6.1.2)
Classification of organisms (4.2.2)
Semiconservative replication, hydrolysis of polymers and enzyme inhibitors (2.1.2, 2.1.3, 2.1.4)
The nitrogen cycle and abiotic factors in ecosystems (6.3.1)
How to use it
Section A is worth 15 of the 100 marks in a 2 hour 15 minute paper, so aim to finish it in about 20 minutes and keep the rest of the time for the written questions. Several questions ask which statement is not true, so check whether each stem wants the correct or the incorrect option before answering. Paper 2 tests modules 1, 2, 4 and 6, so expect Year 12 and Year 13 content side by side.
Where students lost marks on this paper (from the OCR examiners' report and mark scheme)
These points cover the whole paper, not just the multiple choice section. Each is followed by wording that gained marks.
Vague reasons for model organisms: The examiners noted that 'large number of offspring' was not quite good enough, and 'small' was ignored, when explaining why fruit flies are used in research.
✔ Gains credit: low cost, rapid reproduction giving more generations in a given time, well understood genetics and development, and mutations visible with a light microscope.
Replacing one optimum with another: The mark scheme did not accept simply suggesting a different single optimum value, such as pH 5.75.
✔ Gains credit: no values were measured between pH 5.5 and pH 6, so the optimum could lie anywhere in that range, and there is no indication the experiment was repeated.
One-sided evaluations: For the supporting mark, some suggestion of the evidence for the conclusion was needed, not just agreement.
✔ Gains credit: stating that the calculated polymorphism is higher for one species, then giving limitations such as similar values, no statistical test, possibly different loci sampled and unknown sample size.
Confusing q with q squared: A common response treated the proportion of non-rollers as q rather than q² in the Hardy-Weinberg calculation.
✔ Gains credit: the frequency of the homozygous recessive phenotype equals q², so take its square root to find q, use p = 1 minus q, then calculate 2pq for heterozygotes.
Interphase is not a mitosis stage: Listing interphase or cytokinesis along with the stages of mitosis limited the answer to one mark.
✔ Gains credit: naming only the four stages of mitosis (prophase, metaphase, anaphase, telophase) in the correct order.
Cells that make energy: The mark scheme did not accept mitochondria that 'make energy', or enzymes that break down an egg 'cell wall'.
✔ Gains credit: many mitochondria to supply ATP for movement, or an acrosome containing enzymes to digest the outer layer of the egg.
Roles of cytokines and opsonins: The mark scheme ignored 'increase phagocytosis' for cytokines unless it referred to movement of phagocytes.
✔ Gains credit: cytokines attract phagocytes, while opsonins bind to pathogens and make them easier for phagocytes to recognise.
Keep practising
Try the multiple choice sections of the November 2020 Biological Processes paper, or practise by topic with the Genetics and Evolution, Biodiversity, Communicable Diseases, Cell Structure quizzes. You can also 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.
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