7 (a) Define the term ecosystem. … … … … [2] (b) Fig. 7.1 shows some of the living organisms found in a pond ecosystem. cattail otter mayfly frog trout heron pondweed Fig. 7.1 Mayflies eat pondweed. Trout eat mayflies. Herons eat trout. Construct a food chain using this information. … [2] (c) Fertilisers high in nitrates pollute the pond in Fig. 7.1 causing algae to grow on the surface of the water. (i) Explain why producers under the surface of the water die. … … [1] (ii) Explain why the death of producers causes a lack of oxygen in the water. … … [1] (iii) Explain why a lack of oxygen in the water causes a reduction in the population of herons. … … … … [2] [Total: 8]

7(a) unit containing all organisms and their environment ; interacting together ; 2 7(b) pondweed → mayfly → trout → heron ;; one mark for organisms in correct order one mark for arrows 2 7(c)(i) light blocked so no photosynthesis / no light available for photosynthesis ; 1 7(c)(ii) reference to decomposition / respiration / decomposers, uses up oxygen ; 1 7(c)(iii) trout / fish, die ; heron has lost food source ; 2

7 (a) Fig. 7.1 shows a picture of a sloth and some information about sloths. Sloths live in the Amazon rainforest. They feed on the leaves of trees. Sloths are eaten by an animal called a jaguar. Fig. 7.1 (i) Use the information in Fig. 7.1 to construct the food chain for the sloth. … [2] (ii) Complete this sentence about the sloth. The sloth is a … consumer because it eats the producer. [1] (b) Rainforests are being destroyed by deforestation. Fig. 7.2 shows the area of deforestation each year in the Amazon rainforest. 1994 1996 1998 2000 2002 2004 2006 2010 2008 0 5 000 10 000 15 000 20 000 25 000 30 000 year area of deforestation / km2 Fig. 7.2 (i) State the year that had the greatest amount of deforestation. … [1] (ii) Explain why the trend seen in deforestation between 2004 and 2010 benefits sloths. … … … … [2] (c) Plants in the rainforest take up water and mineral ions from the soil. Fig. 7.3 is a diagram showing some of the cells in the root of a plant. root hair soil particles root…cell xylem vessel Fig. 7.3 (i) Complete the label on Fig. 7.3 to identify the cells between the root hair and the xylem vessels. [1] (ii) Draw one arrow to show the pathway taken by water from the soil into the root. [1] (iii) Describe how water moves in and out of cells. … … … [2] [Total: 10]

7(a)(i) leaves → sloth → jaguar correct order ; arrows in right direction ; 2 7(a)(ii) primary ; 1 7(b)(i) 1995 ; 1 7(b)(ii) any two from: amount of deforestation is decreasing ; less habitat being destroyed ; decrease in (the rate of) loss of leaves / food source ; 2 7(c)(i) cortex ; 1 7(c)(ii) arrow drawn going into the root hair ; 1 7(c)(iii) by, diffusion / osmosis ; through a partially permeable membrane ; 2

7 (a) Fig. 7.1 shows information about the organisms in a food chain. grass – producer owl – tertiary consumer cricket – primary consumer frog – secondary consumer Fig. 7.1 (i) Write down the food chain using the information in Fig. 7.1. … [2] (ii) Define the term producer. … … … [2] (b) Explain why chemical digestion is needed in the alimentary canals of consumers. … … … … [2] (c) (i) State why deforestation can disrupt the food chains in a forest. … … [1] (ii) State one other harmful effect of deforestation. … [1] [Total: 8]

7(a)(i) grass cricket frog owl organisms in correct order ; arrows in correct direction ; 2 7(a)(ii) (an organism that) makes its own (organic) nutrients/food ; using energy from (sun)light / photosynthesis ; 2 7(b) any two from: the breakdown of large, insoluble food molecules ; into small water-soluble molecules ; so (small molecules) can be absorbed ; 2 7(c)(i) loss of shelter / loss of habitat / loss of food / reduction in population of part of food chain ; 1 7(c)(ii) loss of soil / flooding / increase of carbon dioxide in the atmosphere ; 1

4 (a) Fig. 4.1 shows a simplified diagram of the carbon cycle. carbon dioxide in the atmosphere green plants respiration fossilisation respiration respiration feeding Y Y X decomposers fossil fuels animals photosynthesis Fig. 4.1 (i) Name process X. … [1] (ii) Name process Y. … [1] (iii) Explain the effect of clearing forests on the concentration of carbon dioxide in the atmosphere. … … … [2] (b) Nitrate ions can be added to water in a lake accidentally. The effects of this can lead to the death of organisms living in the water. Use the words in the list to complete the sentences which explain how this happens. Each word can be used once, more than once, or not at all. addition death decomposers decreased feeding growth increased respiration • There is an increased availability of nitrate ions. • This results in an increased … of producers on the surface of the lake. • This leads to … decomposition after the … of producers. • Increased aerobic respiration by … occurs which results in a reduction of dissolved oxygen. • This causes the death of organisms in the water. [4] [Total: 8]

4(a)(i) combustion / burning ; 1 4(a)(ii) death / excretion / egestion ; 1 4(a)(iii) (increases) less photosynthesis / fewer trees to photosynthesise ; so CO2 not taken in / fewer trees to take in carbon dioxide ; 2 4(b) growth ; increased ; death ; decomposers ; 4 (a)(i) To earn this mark, you must name 'combustion' or 'burning' as process X. (a)(ii) You get this mark for naming 'death', 'excretion', or 'egestion' as process Y. (a)(iii) For the first mark, explain that there is less photosynthesis or fewer trees to photosynthesise. For the second mark, state that CO2 is not taken in or fewer trees are available to take in carbon dioxide, leading to an increase in atmospheric CO2. (b) You must correctly fill in the blanks with 'growth', 'increased', 'death', and 'decomposers' in the correct order to earn all four marks.

Cambridge IGCSE Combined Science · 0653

IGCSE Combined Science (0653) Human influences on ecosystems past paper questions

Revise IGCSE Combined Science (0653) — Human influences on ecosystems 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.

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

Human influences on ecosystems in IGCSE Combined Science 0653 exams, 2020–2025

Across 2020–2025, Human influences on ecosystems accounted for 39 questions worth 151 marks in Cambridge IGCSE Combined Science (0653) papers.

By year
Year	Questions	Marks
2020	7	16
2021	4	11
2022	4	18
2023	10	41
2024	4	13
2025	10	52

Most-tested subtopics

B16.1 Habitat destruction109 marks
B16.2 Conservation33 marks

Appears in

Paper 1 · 5 qs
Paper 2 · 19 qs
Paper 3 · 7 qs
Paper 4 · 8 qs

All most-tested Combined Science topics

2021 May/Jun · Paper 4 · Q7 · 8 marks
Marking scheme
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2020 Oct/Nov · Paper 3 · Q7 · 10 marks
Marking scheme
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2019 Oct/Nov · Paper 3 · Q7 · 8 marks
Marking scheme
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2019 May/Jun · Paper 4 · Q4 · 8 marks
Marking scheme
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2021 Oct/Nov · Paper 2 · Q13 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 2 Q13
Answer: B
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