Water: past paper questions
Real questions on water
The newest 20 of 46 written questions. Open one to see it on the real paper.
- 9700/21 · October/November 2025 · Q2a[2]
Haemoglobin is a globular protein containing haem groups. Explain how the presence of haem groups allows the haemoglobin molecule to transport oxygen.
See it on the paper → - 9700/21 · October/November 2025 · Q2b[3]
In certain situations, such as during intense exercise, a person may breathe very quickly and deeply. This is known as hyperventilation. This hyperventilation causes more carbon dioxide to be exhaled. As a result, there is a lower concentration of carbon dioxide in the blood that passes through the capillary network in...
See it on the paper → - 9700/21 · October/November 2025 · Q2c(i)[3]
Describe and explain how the tunica media (middle layer of the wall) of blood vessel X adapts the blood vessel for its function.
See it on the paper → - 9700/21 · October/November 2025 · Q2c(ii)[4]
Describe the role of the atrioventricular node (AVN) and the Purkyne tissue in the cardiac cycle.
See it on the paper → - 9700/22 · October/November 2025 · Q1b[1]
Suggest one role of the mucus produced by the goblet cells of the villus.
See it on the paper → - 9700/22 · October/November 2025 · Q1d[3]
In response to the presence of compounds in the gut lumen, enteroendocrine cells synthesise and release peptides (short chains of amino acids) that are cell‑signalling molecules. One of these cell‑signalling molecules is known as GLP‑1. GLP‑1 initiates a number of responses in different body cells. Some of these respon...
See it on the paper → - 9700/41 · October/November 2025 · Q7a[3]
Outline the features of ATP that make it suitable as the universal energy currency.
See it on the paper → - 9700/42 · October/November 2025 · Q10a[3]
Nerve impulses can be transmitted along a myelinated motor neurone to a neuromuscular junction at fast speeds of up to 100 m s –1 . Outline how a transmission speed of 100 m s –1 is achieved by the neurone.
See it on the paper → - 9700/21 · October/November 2024 · Q2a[2]
heart arteries capillaries veins Fig. 2.1 Complete Fig. 2.1 by writing the names of the missing types of blood vessels through which red blood cells travel. Fig. 2.1 shows the types of blood vessels through which red blood cells travel in the circulatory system. (a) In the mammalian circulatory system, red blood cells...
See it on the paper → - 9700/21 · October/November 2024 · Q2b[3]
Water is the main component of blood. It has an important role in the transport of substances around the body. Fig. 2.2 shows the ionic compound sodium chloride dissolving in water. Cl – Cl – Cl – Na + Cl – Cl – Cl – Na + Cl – Na + Cl – Na + Cl – Cl – Na + Na + Na + Cl – Cl – Na + Na + Cl – H O Na + Cl – Cl – Na + Cl –...
See it on the paper → - 9700/41 · October/November 2024 · Q6a(i)[2]
Outline how and where the excretory product urea is made in the body.
See it on the paper → - 9700/41 · October/November 2024 · Q6b[3]
The glomerulus and Bowman’s capsule of the nephron are important in the formation of urine. Outline the role of the glomerulus and Bowman’s capsule in the formation of urine.
See it on the paper → - 9700/41 · October/November 2024 · Q6c[3]
Concentrated urine contains a high concentration of solutes and a small volume of water. Different species of mammals vary in their ability to produce urine with a high solute concentration. Table 6.1 compares the ratio of the solute concentration of urine (U) to the solute concentration of blood plasma (P) in some mam...
See it on the paper → - 9700/43 · October/November 2024 · Q10d[2]
A light trap was used to estimate the total size of a population of B. betularia in a woodland. On night one, 24 moths were captured. These were marked with a small spot of harmless paint. On night two, 29 moths were captured, and 8 of these showed a spot of paint. Use the Lincoln index formula provided to calculate th...
See it on the paper → - 9700/21 · May/June 2024 · Q2a[3]
Water is the main component of blood. Explain how the properties of water make it suitable as the main component of blood.
See it on the paper → - 9700/21 · October/November 2023 · Q1a(i)[3]
Use the information in Table 1.1 to identify and describe the process by which potassium ions enter red blood cells from the blood plasma.
See it on the paper → - 9700/21 · October/November 2023 · Q1a(ii)[2]
Sodium ions and oxygen molecules enter red blood cells. State one similarity and one difference between the processes used by sodium ions and oxygen molecules to enter red blood cells. similarity difference
See it on the paper → - 9700/21 · October/November 2023 · Q1a(iii)[2]
Chloride ions move across the membrane of human red blood cells in a process called the chloride shift. Explain why the chloride shift is important in the transport of carbon dioxide from respiring tissues.
See it on the paper → - 9700/21 · October/November 2023 · Q1b[1]
Scientists studied the uptake of a substance, F, by human red blood cells. The red blood cells were immersed in a solution of substance F for 30 minutes. After this time the scientists recorded two observations: • • the cell surface membrane of the red blood cells showed infoldings (invaginations) an increase in the nu...
See it on the paper → - 9700/22 · October/November 2023 · Q3b(i)[1]
Suggest one advantage of having large gaps between the endothelial cells of the sinusoid, as shown in Fig. 3.1.
See it on the paper →
What examiners said
Candidates needed to use knowledge and understanding of active transport as well as the information in Table 1.1 to answer this question. The strongest answers named active transport as the process and then explained how the data in Table 1.1 supported this conclusion. Candidates who made reference to the sodium-potassium pump were able to gain credit for their understanding of its involvement in...
— Examiner report, October/November 2023, 9700/21 Q1(a)(i) (Cambridge)
This was a challenging question for the majority of candidates. The strongest responses used the data in Table 1.1 to deduce that sodium ions enter red blood cells down a concentration gradient. Candidates then had to use their knowledge of diffusion to recognise that oxygen can enter by simple diffusion but sodium ions, which are charged, enter by facilitated diffusion. Some responses suggested t...
— Examiner report, October/November 2023, 9700/21 Q1(a)(ii) (Cambridge)
The strongest responses showed an understanding that chloride ions enter red blood cells during the chloride shift and hydrogencarbonate ions diffuse out. A few of these went on to explain that this process occurs to maintain electrical neutrality in the red blood cell. Many gave only one idea although the allocation of two marks meant that for full credit at least two correct points needed to be...
— Examiner report, October/November 2023, 9700/21 Q1(a)(iii) (Cambridge)
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