OCR A 3.1.1 · 20 written questions · 39 marks · about 45 minutes · marked as you go
This free quiz has 20 written exam questions on exchange surfaces and ventilation, all taken from OCR A Level Biology A papers (AS and A level, 2016 to 2025). Short answers and calculations 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. The quiz works through the whole of OCR A 3.1.1, from why large organisms need specialised exchange surfaces to how mammals, bony fish and insects ventilate and exchange gases. It includes SA:V and spirometer calculations, micrograph identification and a 'spot the errors' question on ventilation.
What the quiz covers (OCR A spec 3.1.1)
The need for exchange surfaces (3.1.1(a)): SA:V, diffusion distance and why multicellular organisms need specialised surfaces, with an SA:V calculation for an alveolus.
Features of efficient exchange surfaces (3.1.1(b)): large surface area, thin layers and good blood supply in alveoli, gill lamellae and root hairs.
The mammalian gas exchange system (3.1.1(c) and (h)): identifying tissues and cells in light micrographs of the trachea and lungs, and the roles of cartilage, smooth muscle, elastic fibres, goblet cells and ciliated epithelium.
Ventilation in mammals (3.1.1(d)): the diaphragm, intercostal muscles, thorax volume and pressure during inspiration.
Spirometry (3.1.1(e)): labelling lung volumes, linking tidal volume, breathing rate and ventilation rate, and working out oxygen consumption from a spirometer trace.
Fish and insects (3.1.1(f) and (g)): gill adaptations and counter-current flow, the insect tracheal system, and improving a fish gill dissection.
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 25-question Exchange Surfaces and Ventilation multiple choice quiz first.
Open the Exchange Surfaces and Ventilation 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.
Large animals have a small SA:V: Many students write that large multicellular organisms have a large surface area to volume ratio, which is the wrong way round.
✔ Gains credit: Large organisms have a small surface area to volume ratio and a long diffusion distance, so diffusion alone is too slow to meet their demand.
Alveoli have no cell walls: 'Thin cell wall' and 'thin membrane' are not credited for alveoli or gills, because animal cells have no cell walls.
✔ Gains credit: The alveolar wall is one cell thick / made of flattened (squamous) epithelial cells, and is surrounded by many capillaries.
Link surface area to uptake: Answers just say the surface area is large, or that gas exchange is 'more efficient', without saying what the large area achieves. Some wrongly say a large SA:V shortens the diffusion distance.
✔ Gains credit: A larger surface area gives a faster rate of diffusion / greater uptake of oxygen (or more water absorbed by a root hair).
The muscle contracts, not the bronchiole: Students write that the bronchioles contract and relax, rather than the smooth muscle in their walls.
✔ Gains credit: Smooth muscle contracts to constrict the lumen of the bronchiole, or relaxes to dilate it.
Elastic fibres stretch and recoil: Answers say the elastic fibres let the alveoli stretch but leave out the recoil, and some say the alveoli contract and relax.
✔ Gains credit: Elastic fibres let the alveoli stretch when we breathe in and recoil to help force air out.
External intercostals for breathing in: Students mix up the intercostal muscles, or think pressure in the thorax rises during inspiration.
✔ Gains credit: During inspiration the external intercostal muscles contract and the diaphragm flattens, so thorax volume increases and pressure falls below atmospheric pressure; the internal intercostals contract only in forced expiration.
Ventilation rate ÷ tidal volume: Students divide the wrong way round, or forget to convert dm³ to cm³ before working out breathing rate or tidal volume.
✔ Gains credit: Ventilation rate = tidal volume × breathing rate, with all volumes in the same unit (1 dm³ = 1000 cm³).
Say 'many' or 'branched': When asked how insect and fish structures give a large surface area, answers describe spiracles, tracheal fluid or counter-current flow, or leave out the word that shows there are lots of them.
✔ Gains credit: Insects have many branched tracheae and tracheoles; fish have many gill filaments covered in lamellae.
Keep practising
Try the Exchange Surfaces and Ventilation multiple choice quiz, the Transport in Animals multiple choice quiz, the Cell Differentiation and Stem Cells written quiz or the Transport in Animals 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.