Organisms Exchange Substances with Their Environment | AQA A-Level Biology (7402)

Organisms Exchange Substances with Their Environment

282 questions
19 subtopics
Paper 1, and available on Paper 3
Paper 1 and Paper 3

Organisms Exchange Substances with Their Environment is examined on Papers 1 and 3 of AQA Biology, which draw on topics 1 to 4.

248 recall questions across 19 subtopics.

Sample questions from Organisms Exchange Substances with Their Environment

Answer each one closed book first, then open the answer.

Surface area to volume ratio, metabolic rate and calculations

What do organisms with higher metabolic rates require in terms of exchange?

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A greater rate of exchange of materials such as oxygen, carbon dioxide, nutrients and waste products.
Leaf gas exchange, insect water loss and xerophytes

Describe the diffusion pathway for gases in a dicotyledonous leaf.

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Gases diffuse through stomata into air spaces in the mesophyll, then to the photosynthesising cells.
Inspiration, expiration and pulmonary ventilation rate

What happens to the diaphragm during expiration at rest?

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It relaxes and returns to its domed shape.
Digestion of carbohydrates and lipids

Where are membrane-bound disaccharidases located?

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Attached to the epithelial cell membranes of the small intestine.
Co-transport of amino acids, micelles and chylomicrons

How do glucose and amino acids move from epithelial cells into the blood?

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They accumulate inside the cells and then diffuse through the basal membrane into the blood.
Cooperative binding, the Bohr effect and different haemoglobins

What is the Bohr effect?

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Increased carbon dioxide concentration causes haemoglobin to release oxygen more readily
Heart chambers, the cardiac cycle and heart dissection

What happens during atrial systole?

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The atria contract, increasing atrial pressure and pushing blood through open atrioventricular valves into the ventricles
Tissue fluid, cardiovascular risk factors and semilunar valves

By what process does water return to the blood at the venous end of capillaries?

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Osmosis

The 19 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Surface area to volume ratio, metabolic rate and calculations	Recall questions on why surface area to volume ratio falls as size increases, why large organisms need exchange surfaces and transport systems, and calculating the ratio for cubes, spheres and cylinders.	24
Gas exchange in single-celled organisms, insects and fish	Recall questions on diffusion across the surface of single-celled organisms, spiracles and tracheoles in insects, gill filaments, lamellae and the counter-current principle in fish, and dissecting fish gills.	13
Leaf gas exchange, insect water loss and xerophytes	Recall questions on stomata and air spaces in the mesophyll of dicotyledonous leaves, how insects limit water loss through their spiracles, and the adaptations of xerophytic plants.	11
Trachea, bronchi, alveoli and lung dissection	Recall questions on the lungs, trachea, bronchi, bronchioles and alveoli, how the alveolar epithelium and blood supply suit gas exchange, ventilation, and what a lung dissection shows.	15
Inspiration, expiration and pulmonary ventilation rate	Recall questions on the roles of the diaphragm and external and internal intercostal muscles in breathing in and out, forced expiration, and calculating pulmonary ventilation from tidal volume and breathing rate.	13
Lung disease, correlation, insect tracheae and Spearman's rank	Recall questions on how lung disease reduces gas exchange, correlation, causation and risk-factor data, the insect tracheal system, and using scattergrams and Spearman's rank correlation coefficient.	20
Digestion of carbohydrates and lipids	Recall questions on digestion by hydrolysis, amylases and membrane-bound disaccharidases such as maltase, sucrase and lactase, and lipid digestion by lipase after emulsification by bile salts.	13
Endopeptidases, exopeptidases and dipeptidases	Recall questions on where endopeptidases, exopeptidases and membrane-bound dipeptidases hydrolyse peptide bonds, why they work faster together, and where and how the products of digestion are absorbed.	10
Co-transport of amino acids, micelles and chylomicrons	Recall questions on co-transport of sodium ions with glucose and amino acids in the ileum, how micelles deliver fatty acids and monoglycerides to epithelial cells, and how chylomicrons enter the lacteals.	16
Haemoglobin, red blood cells and the dissociation curve	Recall questions on the quaternary structure and haem groups of haemoglobin, how red blood cells suit oxygen transport, loading and unloading of oxygen, and the shape of the oxyhaemoglobin dissociation curve.	14
Cooperative binding, the Bohr effect and different haemoglobins	Recall questions on how binding of the first oxygen molecule makes further binding easier, the Bohr effect of carbon dioxide on the dissociation curve, and why organisms have different haemoglobins.	12
Double circulation and the major blood vessels	Recall questions on the pulmonary and systemic circulations of mammals, the advantage of a double circulation, the vessels entering and leaving the heart and kidneys, and the coronary arteries.	12
Heart chambers, the cardiac cycle and heart dissection	Recall questions on the chambers, septum and valves of the heart, pressure and volume changes in atrial systole, ventricular systole and diastole, cardiac output, and safely dissecting and drawing a heart.	25
Arteries, arterioles, veins and capillaries	Recall questions on how the walls and lumen of arteries, arterioles and veins relate to their functions, the valves in veins, and how thin walls and narrow lumens suit capillaries.	12
Tissue fluid, cardiovascular risk factors and semilunar valves	Recall questions on how tissue fluid forms and returns to capillaries and the lymph, risk factors for cardiovascular disease and correlation versus causation, and the position and action of the semilunar valves.	16
Xylem structure and the cohesion-tension theory	Recall questions on the hollow, lignified vessels and pits of xylem, and how transpiration, cohesion and adhesion move water up the stem by cohesion-tension without using ATP.	12
Phloem structure, companion cells and translocation	Recall questions on translocation, sieve tube elements with their sieve plates and reduced cytoplasm, companion cells and plasmodesmata, and loading sucrose at the source in the mass flow hypothesis.	13
Mass flow from source to sink, tracers and ringing	Recall questions on how water entering at the source and leaving at the sink drives mass flow in phloem, why translocation needs energy, and what tracer and ringing experiments show.	13
Evaluating mass flow, potometers and transpiration rate	Recall questions on the evidence for and against the mass flow hypothesis, how light, temperature, humidity and air movement affect transpiration, and measuring water uptake with a potometer.	18

Organisms Exchange Substances with Their Environment is 282 of the 1,977 questions in the guide.Get the guide, £8

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.