AQA A Level Biology (7402) · Paper 1 and Paper 3
AQA A Level Biology 3.3 Exchange with the Environment Exam Questions
Free AQA A Level Biology exam questions by topic for 3.3 Organisms exchange substances with their environment, with a mark scheme for every pack. Covers surface area to volume ratio, gas exchange, digestion and absorption, haemoglobin, the heart and transport in plants.
3.3 Exchange with the Environment exam questions by subtopic
5 question packs covering every part of the specification, with thousands of real past exam questions between them. Do not stop after a few: answer as many as you can, without notes, and mark each one with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About AQA A Level Biology topic 3.3
Topic 3.3 explains how organisms get what they need and remove waste. It starts with surface area to volume ratio, then covers gas exchange in insects, fish, plants and humans, digestion and absorption, and mass transport in animals and plants. Expect graph questions on oxygen dissociation curves and the cardiac cycle.
What you need to know for 3.3 Exchange with the Environment
- 3.3.1 Larger organisms have a smaller surface area to volume ratio, so they need specialised exchange surfaces and mass transport.
- 3.3.2 Gas exchange in single-celled organisms, insects (spiracles, tracheae and tracheoles), fish (gill filaments, lamellae and countercurrent flow) and dicotyledonous plants. The human lungs, ventilation, and pulmonary ventilation = tidal volume x ventilation rate.
- 3.3.3 Digestion of carbohydrates, lipids and proteins by amylase, membrane-bound disaccharidases, lipase with bile salts, and endopeptidases, exopeptidases and dipeptidases. Absorption by co-transport and through micelles.
- 3.3.4.1 Haemoglobin and the oxygen dissociation curve, the Bohr effect, the mammalian circulatory system, the cardiac cycle, blood vessels and the formation of tissue fluid.
- 3.3.4.2 Transport of water in the xylem by cohesion-tension, and translocation in the phloem by mass flow, with evidence from ringing and tracer experiments.
Common mistakes in 3.3 Exchange with the Environment
- Describing countercurrent flow vaguely. Say that blood and water flow in opposite directions, so a diffusion gradient is maintained along the whole length of the lamellae.
- Getting the Bohr effect backwards. More carbon dioxide lowers haemoglobin's affinity for oxygen, so the curve shifts to the right.
- Mixing up when valves open and close in the cardiac cycle. A valve opens when pressure behind it is higher than pressure in front of it.
- For tissue fluid, forgetting that water returns at the venule end by osmosis because plasma proteins lower the water potential of the blood.
- Saying xylem transport needs energy. It is passive; it is phloem loading at the source that uses ATP.
Try three 3.3 Exchange with the Environment exam-style questions
1. Explain how the countercurrent principle allows efficient gas exchange in fish gills. (3 marks)
Show the mark scheme answer
Water and blood flow in opposite directions; blood always meets water with a higher oxygen concentration; so a diffusion gradient is maintained across the whole length of the lamellae.
2. A person has a tidal volume of 0.5 dm3 and a breathing rate of 15 breaths per minute. Calculate their pulmonary ventilation. (1 mark)
Show the mark scheme answer
0.5 x 15 = 7.5 dm3 per minute.
3. Describe how tissue fluid is formed. (2 marks)
Show the mark scheme answer
High hydrostatic pressure at the arteriole end of a capillary; forces water and small molecules out of the capillary.
Want more? Every pack above has many more past exam questions on exchange with the environment.
3.3 Exchange with the Environment FAQs
What does AQA A Level Biology topic 3.3 cover?
Topic 3.3, Organisms exchange substances with their environment, covers surface area to volume ratio, gas exchange, digestion and absorption, haemoglobin, the heart and transport in plants.
Which AQA A Level Biology paper is topic 3.3 on?
Topic 3.3 is examined in Paper 1, which covers topics 3.1 to 3.4. Paper 3 can also include questions on any topic, so it is worth revising for that paper too.
Are these AQA A Level Biology 3.3 exam questions free?
Yes. Every question pack and mark scheme on this page is a free PDF download, with no sign-up needed.
