Exchange and Transport | Edexcel A-Level Biology B (9BI0)

Exchange and Transport

383 questions
23 subtopics
Topics 1 to 4, examined on all three papers
Paper 1, Paper 2 and Paper 3

Why size forces multicellular organisms to evolve exchange surfaces, how substances cross membranes, gas exchange in insects, fish, mammals and plants, the mammalian circulatory system and the blood, and how water and sugars move through a plant..

It covers surface area to volume ratio, the fluid mosaic model, diffusion, osmosis and facilitated diffusion, active transport, endocytosis and exocytosis, gas exchange in insects, fish and mammals, dissecting the insect gas exchange system, gas exchange in flowering plants, the structure of the heart and blood vessels, the double circulatory system, the cardiac cycle, myogenic stimulation and ECG traces, the composition of blood, the functions of blood and clotting, atherosclerosis and its risk factors, haemoglobin and the Bohr effect, oxygen dissociation curves, formation of tissue fluid, the lymphatic system, xylem and phloem structure, apoplastic and symplastic pathways, the cohesion-tension theory, measuring transpiration with a potometer and translocation and the mass flow hypothesis.

Sample questions from Exchange and Transport

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

Surface area to volume ratio

State the formula for calculating surface area to volume ratio.

Show the answer
SA:V ratio = surface area ÷ volume.
Diffusion, osmosis and facilitated diffusion

State the equation used to calculate water potential.

Show the answer
ψ = P + π, where ψ is water potential, P is pressure potential and π is solute potential.
Dissecting the insect gas exchange system

How should the number of organisms used in dissection be managed ethically?

Show the answer
The number used should be minimised.
The structure of the heart and blood vessels

What is the tunica intima of an artery?

Show the answer
The tunica intima is the innermost layer of an artery wall, consisting of endothelium.
Myogenic stimulation and ECG traces

What is the function of the bundle of His?

Show the answer
The bundle of His conducts electrical impulses from the AVN down through the septum to the apex of the heart.
The functions of blood and clotting

What is the role of thromboplastin and calcium ions in blood clotting?

Show the answer
Thromboplastin and calcium ions catalyse the conversion of prothrombin (inactive plasma protein) to thrombin (active enzyme).
Oxygen dissociation curves

At low partial pressures of oxygen, how does haemoglobin behave in terms of oxygen binding?

Show the answer
Haemoglobin has low affinity and binds oxygen slowly.
The lymphatic system

Through which structures does lymph travel after entering lymphatic capillaries?

Show the answer
Lymph travels through lymphatic vessels.

The 23 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Surface area to volume ratio	Recall questions on why surface area to volume ratio falls with size and what that means for exchange surfaces and mass transport, and on calculating the ratio for cubes, spheres, cylinders and rectangular prisms.	19
The fluid mosaic model	Recall questions on the fluid mosaic model, membrane thickness, intrinsic and extrinsic proteins, cholesterol, glycoproteins, glycolipids and receptors, and the beetroot investigation of how temperature affects membrane permeability.	11
Diffusion, osmosis and facilitated diffusion	Recall questions on passive transport and simple diffusion, facilitated diffusion through carrier and channel proteins, osmosis and aquaporins, which molecules cross the bilayer directly, the water potential equation, and finding the water potential of plant tissue with sucrose solutions.	20
Active transport, endocytosis and exocytosis	Recall questions on endocytosis, exocytosis, phagocytosis and pinocytosis, active transport by carrier proteins, the role of ATP, and how phosphorylation of ADP and hydrolysis of ATP make it the universal energy currency.	15
Gas exchange in insects, fish and mammals	Recall questions on tracheae and spiracles, the counter-current gill, and alveolar structure and ventilation.	33
Dissecting the insect gas exchange system	Recall questions on dissecting an insect to reveal its gas exchange system: the tools used, removing the exoskeleton, identifying spiracles and silvery-white tracheae, recording observations, and the ethical handling and disposal of the organisms.	10
Gas exchange in flowering plants	Recall questions on stomata and guard cells, gas exchange through the air spaces and moist cell walls of the spongy mesophyll, the balance with water loss, and lenticels in woody stems and roots.	14
The structure of the heart and blood vessels	Recall questions on the chambers, valves and vessels, and on how artery, vein and capillary structure fits function.	16
The double circulatory system	Recall questions on the advantages over a single circulation, and on the comparison with bony fish.	8
The cardiac cycle	Recall questions on the atrioventricular and semilunar valves, atrial and ventricular systole and diastole, cardiac output, stroke volume and heart rate calculations, and reading valve movements and pressure changes from a pressure graph.	25
Myogenic stimulation and ECG traces	Recall questions on the SAN, AVN and bundle of His, and on interpreting the P, QRS and T features of an ECG.	16
The composition of blood	Recall questions on plasma, erythrocytes, and the leucocytes including neutrophils, eosinophils, monocytes and lymphocytes.	11
The functions of blood and clotting	Recall questions on what blood transports and how it defends against pathogens, platelets, and the clotting cascade from thromboplastin and calcium ions through prothrombin and thrombin to a fibrin mesh.	8
Atherosclerosis and its risk factors	Recall questions on the stages of atherosclerosis from endothelial damage to atheroma, arteriosclerosis and thrombosis, its effects on the heart and brain, its risk factors, and reading scatter diagrams and correlation against causation for lifestyle data.	23
Haemoglobin and the Bohr effect	Recall questions on the quaternary structure of haemoglobin and its haem groups, cooperative binding, the Bohr effect and its mechanism through carbonic acid and hydrogen ions, and the forms in which carbon dioxide is carried in the blood.	22
Oxygen dissociation curves	Recall questions on reading the sigmoid curve, comparing foetal and adult haemoglobin, and myoglobin.	23
Formation of tissue fluid	Recall questions on hydrostatic and oncotic pressure at each end of a capillary bed, and what tissue fluid contains.	22
The lymphatic system	Recall questions on lymph, why about a tenth of tissue fluid is not reabsorbed into capillaries, its drainage through blind-ended lymphatic capillaries and vessels, its return to the blood, and how the system prevents oedema.	8
Xylem and phloem structure	Recall questions on xylem vessels and lignification, and on sieve tube elements and companion cells.	18
Apoplastic and symplastic pathways	Recall questions on the two routes across a root, the Casparian strip, and where each pathway is blocked.	8
The cohesion-tension theory	Recall questions on cohesion and adhesion, how transpiration pulls an unbroken column of water up the xylem, embolisms, and how temperature, light intensity, humidity and air movement affect the rate of transpiration.	10
Measuring transpiration with a potometer	Recall questions on setting up a potometer underwater without air bubbles, calculating the rate of water uptake from bubble movement, the variables to change and control, why uptake is not exactly transpiration, and reducing percentage error in the distance measured.	25
Translocation and the mass flow hypothesis	Recall questions on source and sink, active loading at the source, and the evidence for and against mass flow.	18

Exchange and Transport is 383 of the 2,073 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.