OCR A 3.1.2 · 20 written questions · 46 marks · about 55 minutes · marked as you go
This free quiz has 20 written exam questions on transport in animals, 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.
What the quiz covers (OCR A spec 3.1.2)
Why large, active animals need a transport system, and why insects manage with an open circulatory system
Single and double, open and closed circulatory systems
Arteries, arterioles, capillaries and veins, including valves in veins
Tissue fluid: hydrostatic and oncotic pressure, net pressure calculations and lymph
The structure of the heart, the SAN, AVN, septum and Purkyne fibres
The cardiac cycle: pressure graphs, valves and a ventricular septal defect
Cardiac output and heart rate calculations, and reading ECG traces
Haemoglobin, carbonic anhydrase, the chloride shift, the Bohr effect and fetal haemoglobin
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 37-question Transport in Animals multiple choice quiz first.
Open the Transport in Animals 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.
Explain, don't just state: Most students knew that valves in veins prevent backflow, but only stated it. Some wrote about the valves in the heart instead of veins.
✔ Gains credit: Valves stop the backflow of blood because the pressure in veins is low, so blood can only flow one way, back towards the heart.
Insects get oxygen from tracheae: Many students did not realise that insects get oxygen through the tracheal system, separately from the circulatory system. Some said insects have a low metabolic rate, but in flight it can be up to 100 times the resting rate.
✔ Gains credit: Tracheae and tracheoles take oxygen directly to the tissues and the haemolymph does not carry oxygen, so a high-pressure, fast-flowing system is not needed.
Plasma proteins create oncotic pressure: Many students described oncotic pressure as blood pressure or hydrostatic pressure, and most answers did not mention plasma proteins or water potential.
✔ Gains credit: Plasma proteins such as albumin are too large to leave the capillary, so they lower the water potential of the blood; water moves back into the capillary by osmosis.
Give the error and the correction: When asked to correct a student's description of the cardiac cycle, many students copied long sections without saying which part was wrong. An error without its correction earns very little.
✔ Gains credit: A clear layout for each one: Error: quote the wrong phrase. Correction: write what it should say, using the correct term.
Multiply, and beats aren't a unit: In cardiac output calculations some students divided one value by the other, and many gave the unit as cm³/bpm.
✔ Gains credit: Cardiac output = stroke volume × heart rate, with the unit cm³ min⁻¹ (or dm³ min⁻¹).
Measure a whole heartbeat on the ECG: Only a few students measured an ECG trace correctly. Most didn't notice that the scale bar was shorter than one heartbeat, and some ignored 'give your answer to the nearest whole number'.
✔ Gains credit: Measure from one R peak to the next against the scale bar, work out 60 ÷ the time for one beat, then round as the question asks.
Brady means slow: A slow heart rate on an ECG was often spelt 'brachycardia', which OCR did not accept. Both the abnormality and a reason were needed for the mark.
✔ Gains credit: Bradycardia, because the gap between the T wave and the next P wave (or between QRS complexes) is longer than normal.
Exercise lowers haemoglobin's affinity: Some students misread the dissociation curves and said haemoglobin's affinity for oxygen increases during exercise; others compared maternal and fetal haemoglobin without mentioning partial pressure.
✔ Gains credit: More carbon dioxide shifts the curve to the right, so at the same pO₂ haemoglobin is less saturated and releases oxygen more readily to respiring muscle. In the placenta, the low pO₂ makes maternal haemoglobin release oxygen, which fetal haemoglobin, with its higher affinity, picks up.
Keep practising
Try the Transport in Animals multiple choice quiz, the Cardiac Cycle quiz, the Exchange Surfaces quiz or the Transport in Plants 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.