Biological reactions are regulated by enzymes: Eduqas A‑Level Biology questions

Every Eduqas A-Level Biology exam question on C.4 Biological reactions are regulated by enzymes, 2016–2025, with its mark scheme and examiner’s report.

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2,061 questions

Q4(d)(i)
June 2025 · Component 1
2 marksC.4 Biological reactions are regulated by enzymes
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Q4(d)(iii)
June 2025 · Component 1
2 marksC.4 Biological reactions are regulated by enzymes
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$June 2025 Component 1, question 4(d)(iii): There are over 350 000 synthetic chemicals in production globally. At present only a very small fraction of these can be identified using biosensors. Use your k$
Q5(c)(ii)
June 2025 · Component 1
3 marksC.4 Biological reactions are regulated by enzymes
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Q5(d)(i)
June 2025 · Component 1
2 marksC.4 Biological reactions are regulated by enzymes
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Q5(d)(ii)
June 2025 · Component 1
2 marksC.4 Biological reactions are regulated by enzymes
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Q5(d)(iii)
June 2025 · Component 1
3 marks1.3 Respiration releases chemical energy in biological processes C.4 Biological reactions are regulated by enzymes
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Q5(a)(ii)
June 2025 · Component 2
2 marksC.4 Biological reactions are regulated by enzymes
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Q5(d)(v)
June 2025 · Component 2
2 marksC.4 Biological reactions are regulated by enzymes 2.5 Inheritance
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Q4(d)(ii)
June 2025 · Component 3
3 marksC.4 Biological reactions are regulated by enzymes
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Q4(d)(iii)
June 2025 · Component 3
2 marksC.4 Biological reactions are regulated by enzymes
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Q3(a)(i)
June 2025 · AS Component 1
1 markC.4 Biological reactions are regulated by enzymes
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Q3(a)(ii)
June 2025 · AS Component 1
1 markC.4 Biological reactions are regulated by enzymes
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Q3(a)(iii)
June 2025 · AS Component 1
1 markC.4 Biological reactions are regulated by enzymes
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Q3(b)(i)
June 2025 · AS Component 1
1 markC.4 Biological reactions are regulated by enzymes
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Q3(b)(ii)
June 2025 · AS Component 1
4 marksC.4 Biological reactions are regulated by enzymes
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Q3(b)(iii)
June 2025 · AS Component 1
3 marksC.4 Biological reactions are regulated by enzymes
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Q3(c)(i)
June 2025 · AS Component 1
1 markC.4 Biological reactions are regulated by enzymes
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Q3(c)(ii)
June 2025 · AS Component 1
3 marksC.4 Biological reactions are regulated by enzymes
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Q3(c)(iv)
June 2024 · Component 1
2 marksC.4 Biological reactions are regulated by enzymes
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Q2(b)
June 2024 · Component 3
1 markC.4 Biological reactions are regulated by enzymes
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All 90 questions on Biological reactions are regulated by enzymes, as a list

June 2025, Component 1, Q4(d)(i) (2 marks): State two advantages of using immobilised enzymes in a biosensor. [2] I. II.
June 2025, Component 1, Q4(d)(iii) (2 marks): There are over 350 000 synthetic chemicals in production globally. At present only a very small fraction of these can be identified using biosensors. Use your k
June 2025, Component 1, Q5(c)(ii) (3 marks): Image 5.4 isocitrate α-ketoglutarate IDH + + NAD NADH NADH inhibits IDH Use information from Images 5.3 and 5.4 to explain how NADH can act as a competitive inh
June 2025, Component 1, Q5(d)(i) (2 marks): Explain how and why the pH was maintained at pH 7.4. [2] The inhibitory effect of NADH on the activity of IDH is given as percent inhibition (I%). Table 5.5 sho
June 2025, Component 1, Q5(d)(ii) (2 marks): Use the following equation and data from Table 5.5 to calculate the percentage inhibition (I%) for a concentration of 50 μmol NADH. [2] (V0 − V) I% = × 100 V0 w
June 2025, Component 1, Q5(d)(iii) (3 marks): The rate at which NADH transports hydrogen to the electron transport chain increases as the concentration of ATP in the matrix decreases. ATP cannot be stored i
June 2025, Component 2, Q5(a)(ii) (2 marks): Use Image 5.1 to suggest why different enzymes are needed to attach N-acetylgalactosamine and galactose to carbohydrate H. [2]
June 2025, Component 2, Q5(d)(v) (2 marks): Bombay blood group is a very rare blood type. People with this blood type always show up as type O on a blood test, but they can carry the allele for blood grou
June 2025, Component 3, Q4(d)(ii) (3 marks): The results of the experiment showed that the pH of all the saline solutions at the end of the two-hour period was pH 5.0. With reference to Graph 4.2, explain
June 2025, Component 3, Q4(d)(iii) (2 marks): Use Graph 4.4 to identify which type of inhibition is shown by antitrypsin. Explain your answer. [2]
June 2025, AS Component 1, Q3(a)(i) (1 mark): State two variables which were controlled in this investigation. [1]
June 2025, AS Component 1, Q3(a)(ii) (1 mark): Explain why the investigation would be invalid if steps 2 and 4 in the method were not followed. [1]
June 2025, AS Component 1, Q3(a)(iii) (1 mark): Identify the main source of inaccuracy in this investigation. [1]
June 2025, AS Component 1, Q3(b)(i) (1 mark): Calculate the mean for 15 °C. Write your answer in Table 3.1. [1]
June 2025, AS Component 1, Q3(b)(ii) (4 marks): Plot a graph of the mean results on Graph 3.2. Range bars are not required. [4]
June 2025, AS Component 1, Q3(b)(iii) (3 marks): I. Explain why it is not possible to identify the optimum temperature for the lipase used in this experiment using the method outlined. [2] II. Suggest how you
June 2025, AS Component 1, Q3(c)(i) (1 mark): Draw a line on Graph 3.3 to show the effect of the presence of a low concentration of a non-competitive inhibitor of lipase on the concentration of product. [1]
June 2025, AS Component 1, Q3(c)(ii) (3 marks): Use your knowledge of non-competitive inhibitors to explain why you have drawn the line in that position. [3]
June 2024, Component 1, Q3(c)(iv) (2 marks): Suggest an explanation for the results of the experiment for lactose shown in Table 3.3. [2]
June 2024, Component 3, Q2(b) (1 mark): When vinegar (ethanoic acid) is added to potato chips, enzyme A (produced in the mouth) is unable to break down the starch they contain. Suggest the reason for
June 2024, Component 3, Q5(a)(i) (2 marks): Describe what is meant by the term enzyme and explain why the tertiary structure of the enzyme is important to the function of the enzyme. [2]
June 2024, AS Component 1, Q3(b)(i) (1 mark): State the independent and dependent variables in this experiment. [1] Independent variable: Dependent variable:
June 2024, AS Component 1, Q3(b)(ii) (2 marks): Suggest two variables which were not controlled. [2]
June 2024, AS Component 1, Q3(b)(iii) (1 mark): Explain one reason why the volume of juice collected may be lower than expected using the filtration method shown in Image 3.2. [1]
June 2024, AS Component 1, Q3(c)(i) (4 marks): Plot the data in Table 3.3 on Graph 3.4. [4] Graph 3.4
June 2024, AS Component 1, Q3(c)(ii) (4 marks): Use Graph 3.4 to describe and explain the effect of increasing the concentration of pectinase. [4]
June 2024, AS Component 1, Q3(d) (2 marks): The pectinase and pineapple mixture was placed in a water bath at the optimum temperature for the enzyme. If incubation temperature was less than the optimum, t
June 2023, Component 1, Q3(a)(ii) (2 marks): Explain how the induced fit mechanism enables hexokinase to accept both isomers as substrates. [2]
June 2023, Component 1, Q3(c) (3 marks): At rest, blood glucose concentration is usually low and hexokinase catalyses the conversion of glucose to glucose-6-phosphate. An increased concentration of glu
June 2023, Component 2, Q1(a)(i) (1 mark): State the name given to enzymes which work inside cells. [1]
June 2023, Component 2, Q4(e)(iii) (3 marks): An acrosin inhibitor has been suggested as a form of contraception. Explain how a non-competitive inhibitor could act on acrosin to prevent fertilisation. [3]
June 2023, AS Component 1, Q1(b)(iii) (4 marks): Lysozyme is an enzyme which functions in a way that supports the theory of the induced fit hypothesis. Describe the induced fit hypothesis. [4]
June 2023, AS Component 1, Q1(b)(iv) (2 marks): Describe how the lock and key hypothesis is different from the induced fit hypothesis. [2]
June 2022, Component 3, Q3(c)(i) (3 marks): Explain the results shown in Table 3.2. [3] The scientists then poured water into the column which contained immobilised endopeptidase and exopeptidase and coll
June 2022, Component 3, Q3(c)(iii) (2 marks): Using the equation and the information provided, estimate the concentration of the free amino acids collected as a percentage of the resulting liquid when the c
June 2022, Component 3, Q3(c)(iv) (1 mark): When the scientists used a 70 cm column, they found that their estimate was incorrect. With reference to Graph 3.3, suggest why this might be the case. [1]
June 2022, AS Component 1, Q1(c) (2 marks): Plants can synthesise the amino acid isoleucine from a different amino acid, threonine, in a five-step metabolic pathway controlled by five different enzymes as
June 2022, AS Component 1, Q1(d)(i) (3 marks): Describe and explain the results shown in curve A. [3]
June 2022, AS Component 1, Q1(d)(ii) (4 marks): Explain the shape of curve B. [4]
June 2022, AS Component 1, Q6 (9 marks): Lysozyme is an enzyme which catalyses the breakdown of glycosidic bonds in polysaccharides in bacterial cell walls. It works using the induced fit model of enzy
Autumn 2021, Component 3, Q1(b)(ii) (1 mark): State why two different enzymes would be needed to synthesise raffinose. [1]
Autumn 2021, Component 3, Q5(b)(ii) (3 marks): Tapeworms have been found to secrete hydrogen ions (H+) into their surroundings which reduces the pH. Suggest why this may decrease the rate of uptake of digest
Autumn 2021, Component 3, Q8(b)(iv) (2 marks): State why the procedure was carried out at 0 °C using a buffer solution. [2] The scientists concluded that there was very little difference in the molecular mas
Autumn 2021, AS Component 1, Q5(b)(i) (1 mark): Suggest why it is important to rinse the beads with distilled water before use. [1]
Autumn 2021, AS Component 1, Q5(b)(ii) (1 mark): Explain why the same solution of alginate and lactase was used to make all the different sizes of bead. [1]
Autumn 2021, AS Component 1, Q5(b)(iii) (2 marks): Carrying out the experiment at room temperature reduces reproducibility. Explain why and suggest how this could be improved. [2] Table 5.3 shows the mean volume
Autumn 2021, AS Component 1, Q5(c)(i) (5 marks): I. Calculate the mean volume of the 0.2 cm diameter beads. 4 Volume of a sphere = π r3 3 Where π = 3.142 Express your answer to 2 significant figures. Write you
Autumn 2021, AS Component 1, Q5(c)(ii) (3 marks): Predict the relationship between bead diameter and rate of hydrolysis. Explain your answer. [3]
Autumn 2020, Component 1, Q3(c) (2 marks): High levels of ATP within a cell cause the non-competitive inhibition of several enzymes involved in ATP synthesis. Explain how an ATP molecule could act as a n
Autumn 2020, Component 2, Q3(b)(iii) (2 marks): A protease is added to digest enzymes present in the cytoplasm of strawberry cells that could digest the DNA. Explain why you could not use pepsin as the protea
Autumn 2020, Component 3, Q3(b)(i) (1 mark): State the term given to enzymes which work outside cells. [1]
Autumn 2020, Component 3, Q3(b)(ii) (2 marks): Explain why several different types of lipase enzymes are released by the pancreas. [2]
Autumn 2020, Component 3, Q3(c)(i) (3 marks): A tangent has been drawn at 30 seconds, use this tangent to calculate the rate of digestion per second at that time. Give your answer in standard form. [3] Rate
Autumn 2020, Component 3, Q3(d) (1 mark): Image 3.3 shows a ribbon diagram of one type of lipase. Image 3.3 active site This lipase enzyme is a globular protein with the active site labelled. When the s
Autumn 2020, Component 3, Q3(e)(i) (1 mark): Explain why the solutions were left in the thermostatic water bath for 5 minutes before combining. [1]
Autumn 2020, Component 3, Q3(e)(ii) (4 marks): Suggest two sources of inaccuracy in this experimental method that could account for the variation within these results. For each suggestion give one way by whi
Autumn 2020, AS Component 1, Q3(a)(i) (2 marks): State two other variables that should have been controlled during this investigation. [2]
Autumn 2020, AS Component 1, Q3(a)(ii) (4 marks): Identify two sources of inaccuracy in this experimental method and describe how accuracy could be improved in each case. [4]
Autumn 2020, AS Component 1, Q3(b)(i) (4 marks): Plot the mean results of the investigation on the graph paper provided. [4]
Autumn 2020, AS Component 1, Q3(b)(ii) (4 marks): Describe and explain the results of the experiment. [4]
Autumn 2020, AS Component 1, Q3(c)(ii) (2 marks): Explain how the shape of the molecule is related to its function. [2]
June 2019, Component 1, Q2(d) (3 marks): Describe the effect of heat in the process of pasteurisation on the proteins in the bacteria. [3]
June 2019, Component 1, Q4(a) (2 marks): Explain the term allosteric inhibition. [2]
June 2019, Component 1, Q4(b)(ii) (3 marks): Explain how 3-BrPA acts as a potential anti-cancer agent. [3]
June 2019, AS Component 1, Q3(b)(i) (1 mark): The rate of enzyme activity can be altered by the presence of inhibitors. Explain why galactose can act as a competitive inhibitor of lactase. [1] Students inve
June 2019, AS Component 1, Q3(b)(ii) (2 marks): The results for Experiment 1 have been plotted on the graph paper below. Plot the results for Experiment 2 on the same axes. [2] 0.2 Experiment 1 0.18 0.16 0.14
June 2019, AS Component 1, Q3(b)(iii) (2 marks): Explain how the results show that galactose acts as a competitive inhibitor of lactase. [2]
June 2019, AS Component 1, Q3(b)(iv) (1 mark): Describe how the graph would look if galactose was a non-competitive inhibitor of lactase. [1]
June 2019, AS Component 1, Q3(c)(i) (2 marks): Explain why the immobilised lactase works at its maximum rate over a wider range of temperatures than the free lactase. [2]
June 2019, AS Component 1, Q3(c)(ii) (1 mark): Explain why the substance used to immobilise the lactase must be inert. [1]
June 2018, Component 1, Q4(b)(ii) (4 marks): Using the diagram opposite explain how the lack of the debranching enzyme causes low blood glucose. [4]
June 2018, Component 1, Q4(c) (3 marks): Explain what has happened to produce a non-functional glycogen debranching enzyme. [3]
June 2018, Component 3, Q6(b)(i) (2 marks): Describe how the enzymes produced by the bacteria enable them to reach the vascular tissue. [2]
June 2018, AS Component 1, Q2(a) (2 marks): Using letters from the graph, identify the following: [2] • the energy level of the products of an enzyme catalysed reaction • the activation energy of an enzym
June 2018, AS Component 1, Q2(b)(i) (1 mark): Suggest why the activity of ADK would be an advantage to muscle. [1]
June 2018, AS Component 1, Q2(b)(ii) (2 marks): The ‘lock and key’ model of enzyme action was first proposed in 1894 by Emil Fischer and provides a simple explanation of how enzymes and substrates interact. H
June 2018, AS Component 1, Q2(c)(i) (1 mark): State the difference between an intra- and an extra-cellular enzyme. [1]
June 2018, AS Component 1, Q5(c)(iii) (2 marks): Explain why keeping the whole Chlamydomonas extract on ice in a buffer would also improve the quality of data. [2]
June 2017, AS Component 1, Q5(b)(i) (1 mark): The rate of reaction between 0 and 0.5 minutes was calculated as 1.0 a.u.
June 2017, AS Component 1, Q5(b)(ii) (2 marks): Explain the difference between the initial rate and the rate between 0 and 0.5 minutes. [2]
June 2017, AS Component 1, Q5(b)(iii) (3 marks): In addition to the control variables described, identify two other variables that should have been controlled in this experiment to produce valid results. Expla
June 2017, AS Component 1, Q5(c) (3 marks): Explain why the results of this experiment may not provide the evidence needed to reach a valid conclusion on the use of DNase 1 in treating human lung conditio
June 2016, AS Component 1, Q3(b) (2 marks): Modern medicine uses immobilised enzymes, in devices called biosensors, to detect blood glucose levels. This involves the use of glucose oxidase as the enzyme a
June 2016, AS Component 1, Q5(a) (3 marks): Explain what caused the indicator to lose the pink colour and become colourless. [3]
June 2016, AS Component 1, Q5(b) (1 mark): Why would this experiment not be suitable for assessing the effect of different pH values on lipase? [1] Weight loss in obese patients can be achieved by a redu
June 2016, AS Component 1, Q5(c) (3 marks): Describe and explain the action of this drug on pancreatic lipase. [3]
June 2016, AS Component 1, Q5(d)(i) (2 marks): Describe how this drug would lead to weight loss. [2]
June 2016, AS Component 1, Q5(d)(ii) (1 mark): With reference to the action of this drug, explain why people tended to regain the weight when they stopped taking it. [1] During clinical trials of this drug t
June 2016, AS Component 1, Q5(d)(iii) (3 marks): Using all the information given in (c) and (d), state the advantages and disadvantages of using this drug as part of a weight loss programme. [3]
June 2016, AS Component 2, Q6(a)(i) (3 marks): With reference to the structure of starch and cellulose molecules, explain why α amylase is unable to digest cellulose even though starch and cellulose are both

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