Transport in mammals — AS & A Level Biology (9700) questions by topic
The cardiac cycle, valve mechanics and the Bohr shift carry most of the demand in this A Level topic: sequencing atrial and ventricular systole correctly, deducing why the AVN delays the wave of excitation, and explaining how falling blood pH shifts the oxyhaemoglobin dissociation curve. Explain, deduce and identify lead the command words, and deduce specifically wants a reasoned inference from given pressure or timing data, not a recalled fact.
This set gathers 77 real questions from 2023 to 2025 papers, worth 1 to 14 marks, so quick multiple-choice recall sits beside multi-mark explanations of valve timing. Submitting each answer for instant marking is valuable here, since it flags immediately when systole and diastole are described as simple contraction and relaxation rather than by their correct names.
What examiners look for
- A recurring error names the ventricular muscle as smooth rather than cardiac muscle.
- Two frequently unrewarded statements are that thick ventricle walls withstand high pressure, or prevent bursting, without further development.
- The full names of the two heart nodes are often replaced with the abbreviations SAN and AVN, and 'atrioventricular' is commonly misspelled.
- Valve-opening explanations are marked down when they ignore the relative pressures either side of the valve and instead state it opens simply because pressure rises on one side.
- Strong answers add that a higher pressure is needed to overcome resistance from the blood vessels, and explain the AVN delay in terms of allowing the atria to empty before ventricular systole begins.
May–June 2025, Paper 11
The diagram shows the structure of an amphibian heart and the movement of blood through it. The diagram shows a three-chambered heart with two atria and one ventricle, with blood…
Answer this question and get it marked →A mutation in one of the genes that codes for haemoglobin changes the affinity of haemoglobin for oxygen. This mutation lowers the partial pressure of oxygen at which haemoglobin…
Answer this question and get it marked →Which processes are responsible for the Bohr shift? 1 Carbon dioxide reacts with haemoglobin to form carbaminohaemoglobin. 2 Carbon dioxide reacts with water to form carbonic…
Answer this question and get it marked →A student viewed a drop of human blood with a microscope and described a cell as having a very large diameter and a U-shaped nucleus that occupies half the volume of the cell.…
Answer this question and get it marked →May–June 2025, Paper 12
The diagrams show three types of blood cells, which are all drawn to the same scale. Cell X is large with a kidney/U-shaped nucleus, cell Y is medium with a large round nucleus,…
Answer this question and get it marked →The graph shows oxygen dissociation curves for three animals. The shape of each curve is influenced by respiration rate and the affinity of haemoglobin for oxygen. Animal 1…
Answer this question and get it marked →Which statements about a mammalian heart are correct? 1 The right atrium and right ventricle contain deoxygenated blood going to the lungs. 2 The left atrium and left ventricle…
Answer this question and get it marked →How is most carbon dioxide transported in the blood? A as carbaminohaemoglobin B as carbonic acid C as hydrogencarbonate ions D in solution in cytoplasm
Answer this question and get it marked →May–June 2025, Paper 13
A person has an atrial septal defect (ASD) — a hole between the left and right atria. Which statement describes the effect on blood oxygen levels? A More oxygen in the aorta; less…
Answer this question and get it marked →Which statement about the mammalian cardiovascular system is correct? A The aorta carries deoxygenated blood to the lungs. B The pulmonary vein carries deoxygenated blood from the…
Answer this question and get it marked →What is the function of the atrioventricular (AV) node? A It initiates the heartbeat. B It delays transmission of the electrical impulse from the atria to the ventricles. C It…
Answer this question and get it marked →Which statement about haemoglobin saturation is correct at intermediate partial pressures of oxygen? A Haemoglobin is fully saturated at intermediate partial pressures. B…
Answer this question and get it marked →May–June 2025, Paper 14
Which two terms describe the mammalian circulatory system? A open and double circulation B closed and double circulation C closed and single circulation D open and single…
Answer this question and get it marked →One function of an arteriole is to increase or decrease the flow of blood to tissues. Which of these must be present in an arteriole wall to allow this function? 1 collagen 2…
Answer this question and get it marked →The table shows blood pressures in different parts of the circulatory system: aorta = 16.0 kPa; arteriole = 11.3 kPa; arterial end of capillary = 4.7 kPa; venous end of capillary…
Answer this question and get it marked →May–June 2025, Paper 21
Fig. 6.1 is a ribbon model of a molecule of haemoglobin. State the part of the haemoglobin molecule labelled X.
Answer this question and get it marked →May–June 2025, Paper 24
The sinoatrial node (SAN), the atrioventricular node (AVN) and the Purkyne fibres have a role in the initiation and control of heart action. The sinoatrial nodal artery (SN…
Answer this question and get it marked →May–June 2024, Paper 11
The following tissues carry an electrical impulse during the cardiac cycle: (1) atrioventricular node; (2) muscle wall of atria; (3) Purkyne tissue; (4) sinoatrial node. In which…
Answer this question and get it marked →The graph shows changes in the volume of the ventricles during a single cardiac cycle, divided into atrial systole, ventricular systole and diastole. Point P is at the start of…
Answer this question and get it marked →The graph shows how changes in oxygen concentration affect the percentage oxygen saturation of human haemoglobin and cat haemoglobin under normal physiological conditions. The…
Answer this question and get it marked →Which statement is correct about how oxygen combines with haemoglobin?
Answer this question and get it marked →May–June 2024, Paper 12
The diagram shows the internal structure of the mammalian heart. Letter A is at the wall between the left atrium and left ventricle region; letter B is in the septum near the…
Answer this question and get it marked →The diagram shows pressure changes in the left side of the heart during the cardiac cycle, plotting pressure (kPa) against time (s) for the left ventricle, aorta and left atrium.…
Answer this question and get it marked →Which components of blood are present in tissue fluid? The columns are 'phagocytes', 'some proteins' and 'sodium ions'. (key: tick = present, cross = not present)
Answer this question and get it marked →May–June 2024, Paper 13
The diagram shows pressure changes during two cardiac cycles. The graph plots pressure (kPa) against time (s) over two cardiac cycles. Three traces are shown: one representing…
Answer this question and get it marked →An irregular heartbeat may be the result of ineffective electrical stimulation of the atria. Which area of the heart could be damaged, causing this irregular heartbeat? A…
Answer this question and get it marked →The diagram shows the effect of three different concentrations of carbon dioxide on the oxygen dissociation curve for human haemoglobin. The graph plots percentage saturation of…
Answer this question and get it marked →Which reactions will be taking place in blood in a capillary that is next to an alveolus? key: Hb = haemoglobin 1 Hb + 4O2 - HbO8 2 H2O + CO2 - H2CO3 3 H2CO3 - H+ + HCO3- A 1 and…
Answer this question and get it marked →May–June 2024, Paper 23
Arteries, capillaries and veins are three types of blood vessel. Table 3.1 shows some features of these three types of blood vessel. Complete Table 3.1 by using a tick if the…
Answer this question and get it marked →October–November 2024, Paper 11
Some babies are born with a hole between the right and left atria. These babies are found to have an increased number of red blood cells. What is the reason for this increase in…
Answer this question and get it marked →An increase in carbon dioxide in human blood shifts the oxyhaemoglobin dissociation curve to the right. What is the explanation for this effect?
Answer this question and get it marked →'Heart block' is a disease which can result in a lower than normal heart rate. A doctor treating a person with heart block found that electrical impulses were initiated as normal…
Answer this question and get it marked →The pumping action of the heart creates hydrostatic pressure in the blood. The table shows the hydrostatic pressure in a blood capillary. arteriole end of capillary / kPa venule…
Answer this question and get it marked →October–November 2024, Paper 12
The diagram shows a section through the human heart, with four structures labelled A, B, C and D. Label A points to a vessel at the top of the heart; label B points to the chamber…
Answer this question and get it marked →The graph shows how the volume of the left ventricle changes during one cardiac cycle. Ventricular volume is plotted against time, ranging from 100 cm3 down to 40 cm3. Point A is…
Answer this question and get it marked →Which row is correct for an artery? Row inner layer middle layer outer layer --- --- --- --- A smooth layer of endodermis cells collagen, elastic fibres and smooth muscle collagen…
Answer this question and get it marked →October–November 2024, Paper 13
The graph shows the effect of different partial pressures of carbon dioxide (CO2) on the oxygen dissociation curve for haemoglobin. Percentage saturation of haemoglobin with…
Answer this question and get it marked →What happens in the heart at the start of ventricular diastole?
Answer this question and get it marked →The electron micrograph shows a longitudinal section through a blood vessel. The vessel has a very thin wall, just one cell thick, with a narrow lumen containing red blood cells.…
Answer this question and get it marked →A student drew a sketch to show the formation of tissue fluid. The sketch shows a capillary with: label A - blood enters the capillary and pressure increases; label B - red blood…
Answer this question and get it marked →October–November 2024, Paper 21
In the mammalian circulatory system, red blood cells travel through different types of blood vessel as they pass from the heart to respiring tissues and back to the heart. Fig.…
Answer this question and get it marked →February–March 2023, Paper 22
Pneumonia is a severe lung disease that can interfere with gas exchange. A person with pneumonia can be connected to an ECMO machine, which performs the gas exchange functions of…
Answer this question and get it marked →May–June 2023, Paper 11
The photomicrograph shows blood cells as seen using a high-power light microscope. Three white blood cells are labelled 1, 2 and 3. Which row correctly identifies the different…
Answer this question and get it marked →Plan diagrams of two blood vessels are shown, labelled 1 and 2, with structures labelled 3, 4 and 5 and fatty tissue indicated. Vessel 1 has a thicker wall and smaller lumen;…
Answer this question and get it marked →What are found in blood and tissue fluid? 1 carbon dioxide; 2 fatty acids; 3 white blood cells; 4 proteins. A 1, 2, 3 and 4 B 1, 2 and 3 only C 1, 2 and 4 only D 3 and 4 only
Answer this question and get it marked →Which reactions would be slowed down by an inhibitor of carbonic anhydrase? 1 CO2 + haemoglobin - carbaminohaemoglobin; 2 CO2 + H2O - H2CO3; 3 H2CO3 - H+ + HCO3-. A 1, 2 and 3 B 1…
Answer this question and get it marked →Which sequence of letters correctly identifies the order of events during the cardiac cycle? The events are: T atrial walls contract; U impulse is delayed by a fraction of a…
Answer this question and get it marked →The diagram gives information about blood pressure in the left side of the heart during the cardiac cycle, showing pressure /kPa against time /s for the aorta, atrium and…
Answer this question and get it marked →May–June 2023, Paper 12
Which properties of water are essential for its role in the transport of blood in mammals? The options are given as a table with a tick for 'essential' and a cross for 'not…
Answer this question and get it marked →The diagram shows some of the events that happen between the plasma and the red blood cells in the circulatory system. A substance 1 moves from the plasma into the red blood cell…
Answer this question and get it marked →The diagrams show the valves in the heart when viewed in cross-section from above at different stages in the cardiac cycle. Diagram 1 shows the semilunar valves open and the…
Answer this question and get it marked →May–June 2023, Paper 13
What is present in the blood in human veins? 1 chloride ions; 2 carbonic anhydrase; 3 oxyhaemoglobin. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only
Answer this question and get it marked →The photomicrograph shows two blood vessels P and Q, which are part of a network that transports blood around the body. Vessel Q has a thick muscular wall and a small lumen;…
Answer this question and get it marked →The diagram shows a blood capillary and the tissue fluid which surrounds it. Points W and X are in the tissue fluid above the capillary at the arteriole end and venule end; points…
Answer this question and get it marked →What happens during ventricular systole in a mammalian heart? A Aortic pressure increases. B Atrioventricular valves open. C Semilunar valves close. D Ventricular pressure…
Answer this question and get it marked →May–June 2023, Paper 21
Fig. 5.1 is a longitudinal section of a capillary in muscle tissue as viewed with a transmission electron microscope, at magnification x2000. Cells are visible inside the…
Answer this question and get it marked →May–June 2023, Paper 22
The sinoatrial node (SAN) and the atrioventricular node (AVN) have an important role in the control of the cardiac cycle. The timing of atrial and ventricular systole and diastole…
Answer this question and get it marked →May–June 2023, Paper 23
Blood contains white blood cells and red blood cells. Fig. 3.1 is a photomicrograph showing different types of blood cell. It shows numerous red blood cells together with three…
Answer this question and get it marked →October–November 2023, Paper 11
Which factors affect blood pressure? 1 the diameter of the blood vessels 2 the systolic pressure of the heart ventricles 3 the volume of blood returning to the heart in each…
Answer this question and get it marked →Sulthiame is a molecule that inhibits carbonic anhydrase. Which effect would sulthiame have inside a red blood cell in muscle tissue that is respiring at a high rate? A a decrease…
Answer this question and get it marked →The partial pressure of oxygen in blood vessels in different parts of the body affects the percentage saturation of each haemoglobin molecule with oxygen. blood vessel partial…
Answer this question and get it marked →Which statements about the Bohr shift are correct? 1 The shift is accelerated by the action of carbonic anhydrase. 2 A decrease in blood pH will cause oxyhaemoglobin to…
Answer this question and get it marked →Some of the events during a cardiac cycle are listed. 1 Left and right atria contract. 2 Left and right ventricles contract. 3 A wave of electrical activity is conducted by the…
Answer this question and get it marked →October–November 2023, Paper 12
The diagram shows an anterior view of a vertical section through the human heart. Label 1 points to the pulmonary artery, label 2 to a valve between an atrium and a ventricle,…
Answer this question and get it marked →What does the inner layer of veins and capillaries contain? A collagen fibres B elastic fibres C endothelium D smooth muscle
Answer this question and get it marked →The graph shows the changes in blood pressure and water potential across a blood capillary from the arterial end of the capillary to the venous end of the capillary. Blood…
Answer this question and get it marked →Which statement is correct about a red blood cell that has just entered a capillary in a respiring muscle? A There is a net decrease in chloride ions. B There is a net decrease in…
Answer this question and get it marked →The graph shows some blood pressure changes that occur in a human during one cardiac cycle, with pressure plotted against time for the aorta, the left ventricle and the left…
Answer this question and get it marked →October–November 2023, Paper 13
Which process can be carried out by a mature red blood cell? A active transport B cell division C phagocytosis D protein synthesis
Answer this question and get it marked →The photomicrograph shows three white blood cells labelled X, Y and Z. Which row correctly identifies these cells? cell X cell Y cell Z --- --- --- --- A lymphocyte monocyte…
Answer this question and get it marked →When a blood vessel is damaged it can result in problems in the body. Which row identifies the blood vessel that could have been damaged? blood is not being distributed to organs…
Answer this question and get it marked →The diagram shows how tissue fluid is formed. At the arteriole end the outward blood pressure is +4.3 kPa, with -3.3 kPa water potential and additional values +1.1 kPa and -1.3…
Answer this question and get it marked →What happens when carbon dioxide is transported by red blood cells? A Hydrogencarbonate ions move into the red blood cells and chloride ions move into the plasma. B Chloride ions…
Answer this question and get it marked →October–November 2023, Paper 22
The liver receives blood from the hepatic artery and from the hepatic portal vein. The hepatic portal vein transports blood from the digestive system. Hepatocytes are the main…
Answer this question and get it marked →October–November 2023, Paper 23
Haemoglobin is a complex protein molecule made of four separate subunits, as shown in Fig. 3.1. The shading represents the two different polypeptides that form a molecule of…
Answer this question and get it marked →The mammalian heart consists of four chambers. Explain why the ventricles have thicker walls than the atria.
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