Proteins: past paper questions
Real questions on proteins
The newest 20 of 100 written questions. Open one to see it on the real paper.
- 9700/21 · October/November 2025 · Q1d[1]
The R‑groups of amino acids give them different properties. Suggest how the properties of the R‑groups of the amino acids at position 1 of P may differ from the R‑groups of the amino acids at position 2.
See it on the paper → - 9700/21 · October/November 2025 · Q6a(iv)[2]
Lysozyme destroys bacterial cells by hydrolysing bonds in peptidoglycan. Explain how the hydrolysis of bonds in peptidoglycan leads to the destruction of bacterial cells.
See it on the paper → - 9700/23 · October/November 2025 · Q2a(i)[2]
Describe the arrangement of the 3 polypeptides in each molecule of collagen.
See it on the paper → - 9700/42 · October/November 2025 · Q1a[3]
With reference to Fig. 1.1, name: substance A substance B
See it on the paper → - 9700/42 · October/November 2025 · Q1b[1]
Describe how root cells respond to a high concentration of substance B.
See it on the paper → - 9700/42 · October/November 2025 · Q1c(i)[2]
Describe the relationship shown in Fig. 1.2.
See it on the paper → - 9700/42 · October/November 2025 · Q1c(ii)[3]
ABA in rice plant cells inhibits the action of gibberellin. With reference to Fig. 1.1 and Fig. 1.2, explain the importance of ethylene production for the growth of rice plants in flooded fields.
See it on the paper → - 9700/43 · October/November 2025 · Q9b[4]
A biosensor can be used to measure the concentration of glucose in urine. Outline how a biosensor measures the concentration of glucose in urine.
See it on the paper → - 9700/21 · May/June 2025 · Q5a[2]
Suggest why only a small proportion of the absorbed phosphate ions are transported to the growing points.
See it on the paper → - 9700/21 · May/June 2025 · Q5b[4]
Gossypium hirsutum is the most common species of plant grown for the production of cotton across the world. Scientists carried out an investigation to trace the pathway taken by phosphate ions from the leaves of cotton plants into the stems. The scientists used a radioactive isotope of phosphorus ( 32 P) to trace the p...
See it on the paper → - 9700/21 · May/June 2025 · Q6a(iii)[1]
Haemoglobin is described as having quaternary structure. State what is meant by quaternary structure.
See it on the paper → - 9700/22 · May/June 2025 · Q1b[2]
In the symplast pathway, water passes through the cells of the different tissues in the root before entering the xylem vessels of xylem tissue. Name the tissues of the root, in the correct sequence, through which water passes in the symplast pathway.
See it on the paper → - 9700/22 · May/June 2025 · Q1d(ii)[4]
Student X stated that acid phosphatases and sorgoleone could be transported out of root hair cells using the same process. Student Y stated that acid phosphatases and sorgoleone are transported out of root hair cells using different processes. Suggest the reasons given by student X and by student Y to support their sta...
See it on the paper → - 9700/23 · May/June 2025 · Q2a(i)[1]
State the number of carbon atoms in the R group of lysine.
See it on the paper → - 9700/23 · May/June 2025 · Q2a(ii)[2]
Complete the diagram of the structure of lysine in Fig. 2.1.
See it on the paper → - 9700/23 · May/June 2025 · Q2b[3]
Descriptions of the structure of melittin are shown in Table 2.1. Complete Table 2.1 by writing the level of protein structure that applies to each description. Table 2.1 level of protein structure in some conditions, four melittin polypeptides can bind to each other a melittin polypeptide consists of a sequence of 26...
See it on the paper → - 9700/42 · May/June 2025 · Q5b[3]
Diabetes mellitus is a disease in which the blood glucose concentration cannot be controlled. Many people with diabetes mellitus use recombinant human insulin to help control their blood glucose concentration. Explain the advantages of using recombinant human insulin to treat diabetes. Before recombinant human insulin...
See it on the paper → - 9700/42 · February/March 2025 · Q10a[4]
Fig. 10.1 shows chemoreceptor cells in a taste bud. Two of the chemoreceptor cells have formed synapses with sensory neurone dendrites. microvilli support cell chemoreceptor cell sensory neurone dendrite Fig. 10.1 Describe how the contact of sodium ions with the microvilli of the chemoreceptor cell can lead to the rele...
See it on the paper → - 9700/21 · October/November 2024 · Q4b(ii)[4]
A scientist carried out an experiment to study carbohydrate transport in the stem of a woody plant. Fig. 4.3 shows a plan diagram of a transverse section of the stem studied by the scientist. The position of the xylem tissue in the stem is shown. outer stem tissues xylem tissue pith (ii) The scientist carried out a set...
See it on the paper → - 9700/43 · October/November 2024 · Q4a[3]
A touch stimulus to an M. pudica leaf causes an action potential to be generated. The action potential results in changes in cells, which cause the leaf to close. Fig. 4.3 shows the mechanism in M. pudica cells that causes the leaf to close. action potential after touch stimulus protons pumped into extensor cells Cl −...
See it on the paper →
What examiners said
Many responses included relevant details to describe how a neurotransmitter would be released by the cell. Some omitted to describe how sodium ion accumulation led to the entry of calcium ions but described all subsequent steps. Others described earlier steps in the process up to the generation of an action potential, but did not progress beyond this point.
— Examiner report, February/March 2025, 9700/42 Q10(a) (Cambridge)
Most deduced from the description given that secondary structure is used to classify keratin.
— Examiner report, October/November 2023, 9700/22 Q2(a) (Cambridge)
Candidates were asked to consider features contributing to the stability of keratin. The most common point put forward was the existence of the covalent disulfide bonds. Hydrogen bonds were also frequently mentioned, with only a proportion correctly identifying that collectively many hydrogen bonds were providing the stability required. A common error here was to state that hydrogen bonds are stro...
— Examiner report, October/November 2023, 9700/22 Q2(c) (Cambridge)
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