3 Enzymes help to digest food in humans and are produced by different parts of the alimentary canal. (a) The box on the left contains a sentence beginning. The boxes on the right contain some sentence endings. Draw two lines to make two correct sentences about enzymes. Enzymes are carbohydrates. are catalysts that slow down reactions and remain unchanged. are catalysts that speed up reactions and are changed. are catalysts that speed up reactions and remain unchanged. are lipids. are proteins. [2] (b) Fig. 3.1 is a diagram showing an enzyme and several different substrate molecules. T P Q R S enzyme Fig. 3.1 State the letter of the molecule that is most likely to be the substrate for this enzyme. … [1] (c) Enzymes are involved in chemical digestion in humans. Define the term chemical digestion. … … … … … [2] (d) Fig. 3.2 is a graph showing the effect of changes in pH on the activity of four different enzymes, U to X. 1 0 2 3 4 5 6 7 8 9 10 pH 11 U enzyme activity V W X Fig. 3.2 The pH values in different parts of the alimentary canal were measured. Table 3.1 shows the pH values found in the different parts of the alimentary canal. (i) Use the information in Fig. 3.2 to state the letter of the enzyme that would be most active in each part of the alimentary canal. Table 3.1 part of the alimentary canal pH values enzyme letter duodenum 5.5 ileum 8.0 mouth 6.7 stomach 1.5 [2] (ii) The duodenum and ileum are part of the small intestine. State the name of one part of the large intestine. … [1] (e) The acid in gastric juice provides an acid pH for enzymes. (i) State one other function of the acid in gastric juice. … … [1] (ii) State the name of the acid that is found in gastric juice. … [1] (f) Table 3.2 shows the names of some enzymes, the substrate they act on and the products of the reaction they are involved in. It also shows the organ that secretes the enzyme. Complete Table 3.2. Table 3.2 enzyme substrate products organ that secretes the enzyme mylase starch … … … … fatty acids and glycerol pancreas otease … amino acids … [6] [Total: 16]

3(a) are carbohydrates. are catalysts that slow down reactions and remain unchanged. are catalysts that speed up reactions and are changed. Enzymes are catalysts that speed up reactions and remain unchanged. are lipids. are proteins. ;; 2 one mark for each correct line R each additional line 3(b) S ; 1 3(c) breakdown of large molecules into small molecules ; insoluble molecules to soluble molecules ; 2 3(d)(i) ;; part of the alimentary canal pH values enzyme letter duodenum 5.5 V ileum 8.0 X mouth 6.7 W stomach 1.5 U 2 one mark per two correct letters 3(d)(ii) colon / rectum / anus ; 1 3(e)(i) killing bacteria / microorganisms ; 1 3(e)(ii) hydrochloric ; 1 3(f) enzyme substrate products organ that secretes the enzyme amylase starch (named) (simple) sugars / glucose ; salivary glands / pancreas ; lipase ; fats / oils ; fatty acids and glycerol pancreas protease protein ; amino acids stomach / small intestine / pancreas ; 6

5 (a) The four boxes on the left contain definitions of processes carried out by the alimentary canal. The six boxes on the right contain the names of processes. Draw a straight line to join each definition to the matching process. Draw only four lines. The breakdown of large, insoluble molecules into small, soluble molecules. The movement of digested food molecules into the cells of the body where they are used, becoming part of the cells. The passing out of food that has not been digested or absorbed, as faeces, through the anus. The taking of food substances, e.g. food and drink, into the body through the mouth. absorption assimilation chemical digestion egestion mechanical digestion ingestion definition process [4] (b) Fig. 5.1 shows yeast being used to produce alcohol. A mixture of yeast and fruit juice is placed in a jar. Fruit juice contains sugar. A valve lets gas out of the jar but stops gas from entering the jar. valve gas escaping from the liquid jar mixture of yeast and fruit juice Fig. 5.1 (i) State the name of the process that the yeast uses to make alcohol. … [1] (ii) State the name of the gas produced when yeast makes alcohol. … [1] (iii) State the name of the gas that must be stopped from entering the jar when alcohol is being made. … [1] (iv) State the name of the group of chemicals that yeast uses to catalyse the breakdown of glucose molecules. Choose your answer from the list. antibiotics antibodies enzymes hormones … [1] [Total: 8]

5(a) definition process absorption The breakdown of large, insoluble … assimilation The movement of digested food … chemical digestion The passing out of food that has not … egestion The taking of food substances … mechanical digestion ingestion ;;;; 4 one mark for each correct line R each additional line 5(b)(i) anaerobic respiration ; 1 5(b)(ii) carbon dioxide ; 1 5(b)(iii) oxygen ; 1 5(b)(iv) enzymes ; 1 To earn marks, you must draw a straight line from each of the four given definitions to its correct matching process. For part (b), you must state the correct name for the process yeast uses to make alcohol, the gas produced, the gas that must be stopped from entering, and the substance in yeast that causes the reaction.

7 (a) A student investigated the effect of different concentrations of pectinase on the volume of apple juice produced. 1 cm3 of pectinase solution was added to 5 g of mashed apples and the volume of apple juice produced was recorded. Six different concentrations of pectinase solution were tested. The results are shown in Table 7.1. Table 7.1 percentage concentration of pectinase solution volume of apple juice produced / cm3 0 4.4 5 5.0 10 5.4 15 5.8 20 25 7.4 (i) Predict the volume of apple juice produced using pectinase solution with a concentration of 20%. … cm3 [1] (ii) Calculate the percentage increase in the volume of apple juice produced when the concentration of pectinase solution increased from 0% to 10%. Space for working. …% [2] (b) Crops such as apples can be selectively bred. The box on the left contains a sentence beginning. The boxes on the right contain some sentence endings. Draw two lines to make two correct sentences about selective breeding. is carried out over many generations. is caused by mutation. is caused by the environment. requires human involvement. involves one parent only. Selective breeding [2] (c) Some of the statements shown correctly describe events that happen during the process of natural selection. Two of the statements are incorrect. 1 There is no variation within populations. 2 Many offspring are produced so there is more competition for resources. 3 Individuals that are not suited to the environment die. 4 Individuals that are better suited to the environment survive and breed. 5 Offspring pass their alleles to their parents. State the numbers of the two incorrect statements. … and … [2] (d) State the term that is defined as an inherited feature that helps an organism to survive and reproduce in its environment. … [1] [Total: 8]

7(a)(i) any value between 5.81 and 7.39 (cm3) inclusive ; 1 7(a)(ii) 22.7 / 23 (%) ;; 2 MP1 selection of correct values from table, i.e. 5.4 and 4.4 MP2 correct calculation to any number of decimal places 7(b) involves one parent only. is carried out over many generations. Selective breeding is caused by mutation. is caused by the environment. requires human involvement. ;; 2 R each additional line 7(c) 1 ; 5 ; 2 7(d) adaptive (feature) ; 1 To earn marks for part (a)(i), you need to predict a volume of apple juice that falls within the expected range based on the trend in the table. For part (a)(ii), you must select the correct values from the table (5.4 and 4.4) and then perform the correct percentage increase calculation. For part (b), you need to draw two lines connecting 'Selective breeding' to 'is carried out over many generations' and 'requires human involvement'.

8 (a) A student investigated the conditions needed for germination of seeds. Fig. 8.1 shows the apparatus and conditions used. A B light seeds wet soil dark C D light seeds dry soil dark box to exclude light Fig. 8.1 The seeds in test-tubes A and B germinated but the seeds in test-tubes C and D did not germinate. (i) Use the information in Fig. 8.1 to state one condition required for germination. … [1] (ii) Use the information in Fig. 8.1 to state one condition not required for germination. … [1] (iii) The investigation was repeated with seeds that had been boiled for 10 minutes and then cooled. Predict and explain the effect of boiling on the results. … … … … … [2] (b) Photosynthesis and germination have different requirements. (i) State the word equation for photosynthesis. … [2] (ii) State the name of one condition needed for both photosynthesis and germination. … [1] [Total: 7]

2(c) any three from: asexual reproduction: sexual reproduction: 1 both produce offspring / AW 2 one parent two parents 3 genetically identical offspring / clone genetically different offspring 4 no involvement of gametes (named) gametes 5 no fertilisation fertilisation / fusion of gametes 6 no variation variation 7 fast slow 8 mitosis meiosis (and mitosis) 9 less energy required more energy required ;;; 3 one mark per row response does not have to be in a table (a)(i) You earn the mark by stating 'water' or 'moisture' as a condition required for germination, based on the comparison between test-tubes A/B and C/D. (a)(ii) You earn the mark by stating 'light' as a condition not required for germination, based on the comparison between test-tubes A and B. (a)(iii) To earn marks, you must predict that the seeds will not germinate and explain that boiling denatures the enzymes, preventing metabolic processes necessary for germination.

10 A human enzyme was used in an experiment. All factors were kept constant, apart from temperature. What happened to the rate of reaction when the temperature was reduced steadily from 35 C to 5 C? A It decreased steadily. B It increased and then decreased. C It increased steadily. D It remained the same.

Answer: A To earn the mark, a student must correctly state that the rate of reaction for a human enzyme will decrease steadily when the temperature is reduced steadily from 35 °C to 5 °C.

Cambridge IGCSE Biology · 0610

IGCSE Biology (0610) Enzymes past paper questions

Enzyme questions test the lock-and-key model and the effect of temperature and pH on activity.

210 free questions from 2017–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Enzymes in IGCSE Biology 0610 exams, 2020–2025

Across 2020–2025, Enzymes accounted for 266 questions worth 1,421 marks in Cambridge IGCSE Biology (0610) papers.

By year
Year	Questions	Marks
2020	41	245
2021	46	221
2022	49	279
2023	46	182
2024	42	266
2025	42	228

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5.1 Enzymes1240 marks

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Paper 1 · 91 qs
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Paper 4 · 32 qs
Paper 5 · 15 qs
Paper 6 · 18 qs

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2021 Oct/Nov · Paper 3 · Q3 · 16 marks
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2021 May/Jun · Paper 3 · Q5 · 8 marks
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2021 Oct/Nov · Paper 3 · Q7 · 8 marks
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2021 May/Jun · Paper 3 · Q8 · 7 marks
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2021 Feb/Mar · Paper 1 · Q10 · 1 mark
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