This free quiz has all 20 multiple choice questions from Section A of the OCR AS Biology A Breadth in Biology paper (H020/01), June 2023. It marks itself, so you get your score as soon as you finish.
What the multiple choice section covers
Antibiotic resistance and antibody structure (4.1.1)
Simpson's Index of Diversity and conservation (4.2.1)
Binomial names and the kingdoms (4.2.2)
Measuring with an eyepiece graticule and stage micrometer (2.1.1)
Organelles, protein secretion, the cytoskeleton and prokaryotic cells (2.1.1)
Polymers, amino acids, glucose, cellulose, nucleotides and ADP (2.1.2, 2.1.3)
Planning an enzyme investigation and rate units (1.1.1, 1.1.2)
Stem cells and hydrophyte adaptations (2.1.6, 3.1.3)
How to use it
Section A is 20 of the 70 marks on a 1 hour 30 minute paper, so about 25 minutes keeps you on pace for Section B. Examiners advised picking out the key words in each question, and noted that sketching a molecule beside a question helped some candidates.
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.
Alveolar features versus properties: Common errors were 'thin cell wall', which animal cells do not have, and 'short diffusion pathway', which is a property rather than a feature of the surface.
✔ Gains credit: a wall one cell thick made of flattened (squamous) epithelial cells, or being surrounded by a dense capillary network.
Explaining induced fit: Most candidates restated the question or wrote about more enzyme-substrate complexes forming, and few explained how activation energy is lowered.
✔ Gains credit: the change in active site shape forms stronger bonds with the substrate, putting strain on and weakening bonds in the substrate, which lowers the activation energy.
Doubling the uncertainty: The most common error was doubling the absolute uncertainty for a single reading.
✔ Gains credit: percentage error equals the absolute uncertainty divided by the measured value, multiplied by 100, with doubling used only when a value is calculated by difference.
Why amino acids separate in TLC: Many candidates described differences in size or solubility, or called one amino acid more hydrophilic, which was not credited.
✔ Gains credit: the R groups differ in polarity, charge or functional groups, affecting their interactions with the mobile and stationary phases.
Reporting statistical significance: Many candidates used critical values for the wrong number of pairs or just said the value beat everything in the table, and few explained significance clearly.
✔ Gains credit: comparing the calculated rs with the critical value for the correct n, then stating a significant positive correlation at that probability level, less than 5% (or 1%) probability that it is due to chance, so the null hypothesis is rejected.
Cholesterol and membrane fluidity: Many candidates described where cholesterol sits between phospholipid tails instead of addressing the conclusion, and very few realised its effect depends on temperature.
✔ Gains credit: the temperature must be known, because cholesterol increases fluidity at low temperatures and decreases it at high temperatures such as body temperature.
Linking carbohydrates to function: Weaker answers described structures without linking to function, said glucose is released 'easily' rather than rapidly, or did not compare glycogen with starch.
✔ Gains credit: glucose is soluble and a respiratory substrate, starch and glycogen are insoluble and compact for storage, and glycogen is broken down faster than starch because it has more branch ends.
Keep practising
Try the multiple choice sections of the June 2023 Biological Processes paper and June 2023 Biological Diversity paper, or practise by topic with the Cell Structure, Biological Molecules, Transport in Animals, Communicable Diseases 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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