7 (a) Fig. 7.1 shows part of a food web from a lake. perch duck freshwater snail pondweed algae pike stickleback water flea caddis fly larva water beetle Fig. 7.1 (i) Identify one tertiary consumer shown in the food web in Fig. 7.1. … [1] (ii) Identify one herbivore shown in the food web in Fig. 7.1. … [1] (iii) The food web is not complete. Ducks eat freshwater snails and pondweed. Draw two arrows on Fig. 7.1 to complete the food web to include this information. [1] (b) Pondweed can be used to investigate photosynthesis. Fig. 7.2 shows how the gas made by the process of photosynthesis can be collected. gas test-tube water pondweed light funnel beaker Fig. 7.2 (i) State the name of the gas that collects in the test-tube. … [1] (ii) When the light is switched off the experiment in Fig. 7.2 is in the dark and the amount of gas being produced by the pondweed changes. Suggest the change in the amount of gas being produced by the pondweed when the light is switched off. Give a reason for your answer. change in the amount of gas … reason … … [2] (c) Water is needed for the process of photosynthesis. Name the vessels in the plant that transport water. … [1] (d) Glucose is made by the process of photosynthesis. Plants use another process to release energy from glucose. Name the process that releases energy from glucose. … [1] [Total: 8]

7(a)(i) perch / pike ; 1 7(a)(ii) freshwater snail / caddis fly larva / water flea ; 1 7(a)(iii) arrow from freshwater snail to duck AND arrow from pondweed to duck ; 1 7(b)(i) oxygen ; 1 7(b)(ii) less / no, gas produced ; (because) light is needed for photosynthesis ; 2 7(c) xylem ; 1 7(d) (aerobic) respiration ; 1 To earn marks, you must identify 'perch' or 'pike' as a tertiary consumer, and 'freshwater snail', 'caddis fly larva', or 'water flea' as a herbivore. You need to draw two arrows: one from freshwater snail to duck, and another from pondweed to duck. For photosynthesis, you must state 'oxygen' as the gas produced. When light is off, you need to state that 'less' or 'no' gas is produced, and explain that 'light is needed for photosynthesis'. For the plant tissue, you must name 'xylem'. Finally, you must identify 'respiration' (or aerobic respiration) as the process that releases energy from glucose.

1 (a) Fig. 1.1 is a diagram of a fetus inside the uterus. Fig. 1.1 On Fig. 1.1, draw a label line and the letter C to identify the cervix. [1] (b) The fetus requires energy and amino acids for growth. (i) State the name of the process in cells that releases energy. … [1] (ii) Describe how the fetus obtains amino acids. … … … [2] (c) A pregnant female takes iron tablets to supplement her diet. Explain why iron tablets may be needed during pregnancy. … … … [2] (d) Table 1.1 shows the names and functions of some organs associated with the alimentary canal of an adult human body. Complete Table 1.1. Table 1.1 organ function … uses teeth to break down food into smaller pieces large intestine … … egestion [3] [Total: 9]

1(a) cervix labelled anywhere in shaded area ; 1 1(b)(i) respiration ; 1 1(b)(ii) amino acids come from mother's blood ; plus any one from: cross the placenta ; brought to fetus by umbilical cord ; via diffusion ; 2 1(c) idea that fetus needs some of the iron ; reference to any named iron deficiency symptom (in mother) / iron is needed for haemoglobin production ; 2 1(d) organ function mouth ; (uses teeth to breakdown food into smaller pieces) (large intestine) absorbs water ; anus ; (egestion) 3

4 (a) Fig. 4.1 is a diagram of the gas exchange system in a human. P Fig. 4.1 (i) Identify the part labelled P in Fig. 4.1. … [1] (ii) On Fig. 4.1, draw a label line and the letter L to identify the larynx. [1] (b) Expired air contains a different percentage of carbon dioxide to inspired air. State and explain this difference. difference … … explanation … … [2] (c) Fig. 4.2 shows cells that line the airways of a non-smoker and a smoker. non-smoker smoker mucus ciliated cell cilia goblet cell Fig. 4.2 Explain how smoking tobacco affects the function of the cells shown in Fig. 4.2. Use the information in Fig. 4.2 in your answer. … … … … … … [3] [Total: 7]

4(a)(i) diaphragm ; 1 4(a)(ii) larynx labelled ; 1 4(b) difference: more carbon dioxide in expired air ; explanation: because produced in respiration ; 2 4(c) any three from: cilia are, damaged / shorter ; (goblet cells make) more mucus ; pathogens / particles, trapped in the mucus ; idea that it is harder (for cilia) to move the mucus ; idea that, pathogens / particles, are not removed (easily) from the airways ; 3

7 (a) Fig. 7.1 is a graph showing the effect of temperature on two different enzymes, A and B. 0 20 40 60 80 100 temperature / °C enzyme activity A B Fig. 7.1 (i) Identify the temperature at which enzyme A is most active. … °C [1] (ii) Compare the effect of temperature on the two enzymes. … … … … … [3] (iii) Explain the effect of temperature on the activity of enzyme B above 75 °C. … … … [2] (b) Lipase enzymes are found in the small intestine of humans. State the role of lipase enzymes in the small intestine. … … … [2] (c) Enzymes are used in aerobic respiration. Complete the balanced chemical equation for aerobic respiration. … O2 + … … … + … CO2 [2] [Total: 10]

7(a)(i) 40 (°C) ; 1 7(a)(ii) both enzymes increase in activity with increase in temperature ; decrease in activity with increase in temperature over a certain point ; enzyme B is more active at higher temperatures ; 3 7(a)(iii) enzymes denature / shape of active site changes ; substrate no longer fits into active site ; 2 7(b) breaks down, fats / lipids / oils ; forms fatty acids and glycerol ; 2 7(c) 6 (O2) + C6H12O6 → 6 H2O + 6 (CO2) ;; all five answers = 2 marks 3 or 4 correct = 1 mark 1 or 2 correct = 0 marks 2

1 Movement is a characteristic of all living organisms. Which two other characteristics of living organisms provide the energy for movement? A excretion and nutrition B growth and sensitivity C nutrition and respiration D respiration and growth

Answer: C To earn the mark, you must correctly identify nutrition and respiration as the two characteristics that provide energy for movement.

Cambridge IGCSE Combined Science · 0653

IGCSE Combined Science (0653) Respiration past paper questions

Revise IGCSE Combined Science (0653) — Respiration 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.

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

Respiration in IGCSE Combined Science 0653 exams, 2020–2025

Across 2020–2025, Respiration accounted for 102 questions worth 466 marks in Cambridge IGCSE Combined Science (0653) papers.

By year
Year	Questions	Marks
2020	11	58
2021	24	90
2022	18	110
2023	22	100
2024	13	44
2025	14	64

Most-tested subtopics

B12.1 Respiration407 marks

Appears in

Paper 1 · 30 qs
Paper 2 · 29 qs
Paper 3 · 18 qs
Paper 4 · 17 qs
Paper 5 · 3 qs
Paper 6 · 5 qs

All most-tested Combined Science topics

2021 Feb/Mar · Paper 3 · Q7 · 8 marks
Marking scheme
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2021 Oct/Nov · Paper 4 · Q1 · 9 marks
Marking scheme
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2021 Oct/Nov · Paper 4 · Q4 · 7 marks
Marking scheme
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2021 May/Jun · Paper 4 · Q7 · 10 marks
Marking scheme
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2021 Oct/Nov · Paper 1 · Q1 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q1
Answer: C
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