Carbohydrates and lipids: past paper questions
Real questions on carbohydrates and lipids
The newest 20 of 106 written questions. Open one to see it on the real paper.
- 9700/21 · October/November 2025 · Q4a(i)[1]
Draw a circle around a glycosidic bond in Fig. 4.2.
See it on the paper → - 9700/21 · October/November 2025 · Q4a(ii)[2]
In aquatic environments, Vibrio cholerae can live on the surface of copepods. V. cholerae secretes enzymes to hydrolyse chitin to its N‑acetylglucosamine monomers. These can be broken down to provide carbon, nitrogen and a source of energy. Draw the monomer that is formed when chitin is hydrolysed by V. cholerae.
See it on the paper → - 9700/22 · October/November 2025 · Q3d[1]
Fig. 3.1 summarises the reaction catalysed by lactase. CH 2 OH CH 2 OH OH H H O H OH H H O H O H OH H OH H OH CH 2 OH H OH lactase H 2 O OH H H OH O OH H OH H galactose lactose + H α-glucose Fig. 3.1 Draw the ring structure of α‑glucose in the box provided to complete Fig. 3.1.
See it on the paper → - 9700/43 · October/November 2025 · Q2a(i)[2]
Complete Table 2.1 to show one structural difference and one functional difference between E. turcicum and Z. mays. Table 2.1 Z. mays E. turcicum structural difference functional difference
See it on the paper → - 9700/43 · October/November 2025 · Q3a(i)[2]
Calculate the R f value of β‑carotene in Fig. 3.1.
See it on the paper → - 9700/21 · May/June 2025 · Q1a[2]
Amylose and the triglyceride stearin are macromolecules. Explain why amylose and stearin are macromolecules, but only amylose is a polymer.
See it on the paper → - 9700/21 · May/June 2025 · Q1b(i)[3]
3-mark question — its maths and diagrams are best seen on the paper.
See it on the paper → - 9700/21 · May/June 2025 · Q1b(ii)[1]
State the type of covalent bond that is broken in the reaction.
See it on the paper → - 9700/22 · May/June 2025 · Q1c[3]
In the apoplast pathway, water passes along the cell walls of adjacent plant cells and through the intercellular spaces. This is more efficient than the symplast pathway. Explain the structural features of plant cell walls that make the apoplast pathway an efficient pathway for the transport of water.
See it on the paper → - 9700/22 · May/June 2025 · Q3a[1]
One of the sugars found in carrots is galactose. Galactose has the same molecular formula, C 6 H 12 O 6 , as α‑glucose. Fig. 3.1 shows the molecular structure of galactose found in carrots. This is similar, but not identical, to the molecular structure of α‑glucose. In Fig. 3.1, the six carbon atoms are numbered 1 to 6...
See it on the paper → - 9700/22 · May/June 2025 · Q3b[3]
An investigation was carried out to determine the sugar content of mature carrots produced by different local varieties of carrot plants that are grown in Tunisia, North Africa. Carrot plants were grown from seed under standardised conditions. When mature, the carrots were harvested. The different sugars present in the...
See it on the paper → - 9700/22 · May/June 2025 · Q3c[1]
Carbohydrates that are not sugars are also present in carrots. Name one carbohydrate that is present in carrots and that is not a sugar.
See it on the paper → - 9700/43 · May/June 2025 · Q10b(i)[3]
Suggest the assumptions that must be made for the mark-release-recapture method to be valid.
See it on the paper → - 9700/43 · May/June 2025 · Q10b(ii)[2]
A first sample of 27 golden poison dart frogs was captured, marked and released. When a second sample of 33 frogs was captured, 13 had marks on them. Use the Lincoln index to estimate the population size of the frogs. n 1 × n 2 estimate of population size = m 2 n 1 = number of individuals captured in first sample n 2 =...
See it on the paper → - 9700/22 · February/March 2025 · Q2a[2]
Fig. 2.1 is an incomplete diagram of the structure of an α‑glucose molecule. Complete Fig. 2.1 to show the structure of an α‑glucose molecule. CH 2 OH C C C C C O 2
See it on the paper → - 9700/22 · February/March 2025 · Q2b(i)[2]
State the types of covalent bond labelled C and D in Fig. 2.2. C
See it on the paper → - 9700/22 · February/March 2025 · Q2b(ii)[1]
Many glycoproteins in the cell surface membrane are involved in cell signalling. State the role in cell signalling of glycoproteins in cell surface membranes.
See it on the paper → - 9700/22 · February/March 2025 · Q2c[4]
Molecules of β‑casein have a high proportion of the amino acids proline and leucine. These amino acids have hydrophobic R‑groups. Fig. 2.3 compares the structure of proline (Pro) with the general structure of an amino acid. This shows that proline is an unusual amino acid because it has a cyclic R‑group and the nitroge...
See it on the paper → - 9700/21 · October/November 2024 · Q4a(i)[1]
Name the covalent bond that joins the two monomers in sucrose.
See it on the paper → - 9700/21 · October/November 2024 · Q4a(ii)[3]
Sucrose is hydrolysed by the enzyme sucrase in the human digestive system. The products of this hydrolysis reaction are the monosaccharides α-glucose and fructose. Complete the diagram to show the hydrolysis of sucrose to form α-glucose and fructose. CH 2 OH H HO H OH H O H H OH HOCH 2 O O H H HO OH H CH 2 OH
See it on the paper →
What examiners said
Many candidates knew the correct orientation of the –H and –OH on carbon one to distinguish an -glucose molecule from a -glucose molecule, and most completed the rest of the structure correctly. A number of candidates did not fully complete the structure with the –H on carbon 5 being the most common omission.
— Examiner report, February/March 2025, 9700/22 Q2(a) (Cambridge)
Most responses correctly identified both types of covalent bond.
— Examiner report, February/March 2025, 9700/22 Q2(b)(i) (Cambridge)
Some responses referred only to ligand bonding, which can occur in many contexts other than cell signalling. Further qualification, such as an immediate consequence of ligand binding, was required to adequately state the role of glycoproteins in cell signalling.
— Examiner report, February/March 2025, 9700/22 Q2(b)(ii) (Cambridge)
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