10 (a) Plants use different tissues to transport substances around the plant. Circle two parts of a plant that are adapted for transport. capillaries chloroplasts fatty tissue guard cells phloem vena cava xylem [2] (b) Fig. 10.1 is a diagram of a plant cell. X Y Fig. 10.1 (i) Name the cell shown in Fig. 10.1 and state its function. name … function … … [2] (ii) Identify the parts labelled X and Y in Fig. 10.1. X … Y … [2] (c) A scientist investigates the conditions needed for the germination of seeds. She sets up four experiments A–D with different conditions. Table 10.1 shows the conditions for each experiment. Place a tick (3) in Table 10.1 to identify the experiment where the seeds will germinate. Table 10.1 experiment temperature / °C moisture oxygen do seeds germinate? (3) A –20 damp present B –20 dry absent C 20 damp present D 20 dry absent [1] (d) Germination is an enzyme‑controlled reaction. The investigation is repeated with boiled seeds. Describe the effect of boiling on the germination of seeds. Give one reason for your answer. effect … reason … … [2] [Total: 9]

10(a) phloem circled ; xylem circled ; 2 10(b)(i) name root hair (cell) ; function absorption of, water / mineral ions ; 2 10(b)(ii) X cell wall ; Y nucleus ; 2 10(c) prediction of germination (/ X) X X  X ; 1 10(d) effect no germination ; reason (high temperature) decreases enzyme / stops activity ; 2

10 (a) A student writes a definition of an enzyme. The definition is not correct. ‘Enzymes are fats that function as chemical catalysts.’ Circle the two words in the student’s definition that are not correct. [2] (b) Enzymes are used to break down large molecules into smaller molecules. Table 10.1 shows some large molecules and the smaller molecules they are made from. Complete Table 10.1. Table 10.1 large molecules smaller molecules 1. starch 2. … glucose … amino acids fats 1. fatty acids 2. … [3] (c) List the three chemical elements that make up fats. 1 … 2 … 3 … [1] (d) Fig. 10.1 is a graph showing the enzyme activity at different temperatures of four different enzymes, A, B, C and D. –10 enzyme activity 0 10 20 30 40 50 temperature / °C 60 70 80 90 100 110 A B C D Fig. 10.1 Table 10.2 shows average temperatures in different environments. Table 10.2 type of environment average temperature / °C hot springs 50 arctic sea –2 hydrothermal vent region 95 deep sea 2 volcano sediment 75 (i) Describe the effect of temperature on the enzyme activity of enzyme B. Use data to support your answer. … … … … [2] (ii) Use Fig. 10.1 and Table 10.2 to identify the enzyme, A, B, C or D, found in bacteria that can survive in: hydrothermal vent regions … arctic seas … the same environment as enzyme C … [3] [Total: 11]

10(a) fats ; chemical ; 2 10(b) glycogen ; protein ; glycerol ; 3 10(c) carbon hydrogen and oxygen ; 1 10(d)(i) as temperature increases enzyme activity increases then decreases ; peak / optimum at 33 °C ; 2 10(d)(ii) D ; A ; D ; 3 For (a), circle 'fats' and 'chemical'. For (b), complete the table with 'glycogen', 'protein', and 'glycerol'. For (c), list 'carbon', 'hydrogen', and 'oxygen'. For (d)(i), describe the trend as enzyme activity increasing then decreasing with temperature, with a peak/optimum at 33 °C. For (d)(ii), identify enzymes D, A, and D for the respective environments.

1 (a) State the balanced equation for photosynthesis. … [2] (b) A student investigates the effect of temperature on the rate of photosynthesis of an aquatic plant. The student counts the number of bubbles produced per minute at different temperatures. The number of bubbles produced per minute is an indication of the rate of photosynthesis. The results are shown in Table 1.1. Table 1.1 temperature / °C number of bubbles produced per minute 0 0 5 6 10 9 15 13 20 16 25 18 30 17 35 9 40 0 (i) State the temperature that resulted in the fastest rate of photosynthesis. … °C [1] (ii) Place ticks (3) next to all the statements that explain the results between 0 °C and 10 °C. The kinetic energy of the particles increases. There are more frequent collisions between the substrate and enzyme. Fewer substrate molecules fit into the active site of enzymes. The temperature affects the pH of the enzymes. The number of bubbles increases as more substrate is produced. [2] (iii) Explain the results at 40 °C from Table 1.1. … … … … … … [3] (iv) Explain why the light intensity is kept constant during this investigation. … … … … [2] [Total: 10]

1(a) 6CO2 + 6H2O → C6H12O6 + 6O2 ;; 2 1(b)(i) 25 (°C) ; 1 1(b)(ii) the kinetic energy of the particles increases ticked ; there are more frequent collisions between the substrate and enzyme ticked ; 2 1(b)(iii) any three from: photosynthesis has stopped ; the enzymes have become denatured ; the active site has changed shape / the shape of the active site is no longer complementary to the substrate ; substrate no longer fits into, enzyme / active site ; 3 1(b)(iv) a change in light intensity will affect the results ; only the effect of temperature is being investigated / all other variables should be kept constant ; 2 (a) To earn marks, you must write the correct balanced chemical equation for photosynthesis, including all reactants, products, and stoichiometric coefficients. (b)(i) You need to identify the temperature at which the highest number of bubbles was produced from the table. (b)(ii) You must tick both statements that correctly describe the effect of increasing temperature on particle kinetic energy and collision frequency between substrate and enzyme. (b)(iii) To get full marks, you need to explain that photosynthesis has stopped due to enzyme denaturation, which causes the active site to change shape and no longer fit the substrate. (b)(iv) You must state that light intensity affects the results and that it should be kept constant to isolate the effect of temperature.

1 Enzymes have an important role in the process of digestion. (a) Define the term enzyme. … … [2] (b) Fig. 1.1 shows the effect of pH on two different enzymes. 0 1 2 3 4 5 pH enzyme activity 6 7 8 9 10 11 12 A B A B Fig. 1.1 (i) State the pH at which enzyme B is most active in Fig. 1.1. … [1] (ii) Explain the results for enzyme B at pH 10 in Fig. 1.1. … … … … … [3] (iii) State where in the alimentary canal enzyme A is most likely to be found. … [1] (iv) Suggest the name of enzyme A. … [1] (c) Once food is digested, nutrients are absorbed across the villi walls. (i) State where villi are found in the alimentary canal. … [1] (ii) State the function of the lacteal in the villi. … [1] [Total: 10]

1(a) a protein ; (that acts as) a biological catalyst ; 2 1(b)(i) 7.5 ; 1 1(b)(ii) any three from: ref to denaturation ; active site changes shape ; substrate can no longer fit into the, enzyme / active site ; no products released / no breakdown of substances ; 3 1(b)(iii) stomach ; 1 1(b)(iv) protease ; 1 1(c)(i) small intestine ; 1 1(c)(ii) fat absorption ; 1

Cambridge IGCSE Co-ordinated Sciences · 0654

IGCSE Co-ordinated Sciences (0654) Enzymes past paper questions

Revise IGCSE Co-ordinated Sciences (0654) — Enzymes with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

95 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Enzymes in IGCSE Co-ordinated Sciences 0654 exams, 2020–2025

Across 2020–2025, Enzymes accounted for 141 questions worth 707 marks in Cambridge IGCSE Co-ordinated Sciences (0654) papers.

By year
Year	Questions	Marks
2020	20	104
2021	24	96
2022	23	111
2023	27	150
2024	26	170
2025	21	76

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B5.1 Enzymes624 marks

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Paper 1 · 39 qs
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Paper 3 · 11 qs
Paper 4 · 19 qs
Paper 5 · 12 qs
Paper 6 · 16 qs

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2021 May/Jun · Paper 3 · Q10 · 9 marks
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2021 Oct/Nov · Paper 3 · Q10 · 11 marks
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2021 Feb/Mar · Paper 4 · Q1 · 10 marks
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2021 Oct/Nov · Paper 4 · Q1 · 10 marks
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2021 Feb/Mar · Paper 1 · Q4 · 1 mark
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Mark scheme — 2021 Paper 1 Q4
Answer: B
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