Cambridge IGCSE Biology 0610: Human influences on ecosystems – Practice Questions

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs – examination boards hold copyright in their own papers. Use these alongside the official past papers from your board or school.

These questions cover topic 20, Human influences on ecosystems, of the Cambridge IGCSE Biology 0610 syllabus for examination in 2026, 2027 and 2028, sections 20.1 to 20.4. Questions on Supplement content are labelled (Extended); Core candidates (Papers 1 and 3) can leave them out, while Extended candidates (Papers 2 and 4) should attempt everything. Calculators may be used throughout.

See also the IGCSE Biology hub, the 0610 checklist and the Organisms and their environment practice set for food webs and nutrient cycles.

Questions

1. Describe what is meant by biodiversity. [1]

2. State how each of the following has helped humans to increase food production.

(a) chemical fertilisers [1] (b) insecticides [1] (c) herbicides [1] (d) selective breeding [1]

3. A company grows a single variety of soya over 20 000 hectares. Describe two advantages and two disadvantages of large-scale monocultures of crop plants such as this. [4]

4. An intensive poultry unit keeps 24 000 chickens in a shed with a floor area of 3 000 m².

(a) Calculate the number of chickens per m². [1] (b) Describe two advantages and two disadvantages of intensive livestock production. [4]

5. The area of a tropical forest fell from 4.8 million km² to 4.2 million km² over twenty years.

(a) Calculate the percentage decrease in forest area. [2] (b) Suggest two reasons for this habitat destruction. [2] (c) Explain how deforestation can lead to loss of soil and to flooding. [3] (d) Explain how deforestation increases the concentration of carbon dioxide in the atmosphere. [2]

6. This question is about forests as a resource.

(a) Describe what is meant by a sustainable resource. [1] (b) (Extended) Explain how quotas and replanting help to conserve forests. [2] (c) (Extended) Describe two reasons for conservation programmes. [2]

7. A student measured dissolved oxygen at sites along a river. Fertiliser runs off a field into the river at site B.

Site	A (above drain)	B (at drain)	C (200 m below)	D (400 m below)	E (800 m below)	F (1 600 m below)
Dissolved oxygen / mg/dm³	9.2	8.8	3.1	2.4	6.5	8.6

(a) Calculate the percentage decrease in dissolved oxygen from site A to site D. Give your answer to 1 decimal place. [2] (b) (Extended) Explain the fall in dissolved oxygen between site B and site D. [5] (c) Suggest one effect on fish at site D. [1]

8. Describe the effects of non-biodegradable plastics in aquatic and in terrestrial ecosystems. [4]

9. Carbon dioxide and methane are air pollutants.

(a) State one source of carbon dioxide and two sources of methane. [3] (b) Describe how increasing concentrations of these gases lead to climate change. [3]

10. (Extended) A fishery tested two net mesh sizes. With a 40 mm mesh, 62% of the 5 000 fish caught were juveniles that had not yet bred. With an 80 mm mesh, 14% of the 3 200 fish caught were juveniles.

(a) Calculate the number of juveniles caught with each mesh size. [2] (b) Explain how using the 80 mm mesh helps to conserve the fish stock. [2] (c) Explain how two other methods help to conserve fish stocks. [4]

11. The wild population of a rare antelope has fallen to 36 animals.

(a) State three reasons why organisms become endangered. [3] (b) Describe two ways in which endangered species can be conserved. [2] (c) (Extended) Describe how artificial insemination and in vitro fertilisation can be used in a captive breeding programme for the antelope. [3] (d) (Extended) Explain the risk to the antelope species now that its population is so small. [2]

Answers

1. The number of different species that live in an area [1] [1] Examiner insight: “number of organisms” or “variety of life” is not credited; the definition must refer to different species in an area.

2. (a) Supply mineral ions such as nitrate, improving yields [1] (b) Kill insect pests, improving quality and yield [1] (c) Kill weeds, reducing competition with the crop [1] (d) Breeding from the most productive plants or animals improves production [1] Examiner insight: “kills pests” is too vague for insecticides and “kills plants” is wrong for herbicides; name insects and weeds.

3. Advantages, any two: machinery can be used efficiently for planting and harvesting [1]; high yield of one crop [1]; lower cost per unit of food produced Disadvantages, any two: reduces biodiversity [1]; pests and diseases of the crop spread easily [1]; heavy use of pesticides or fertiliser; natural habitats removed Examiner insight: when the question asks for two of each, extra advantages cannot make up for a missing disadvantage.

4. (a) 24 000 ÷ 3 000 = 8.0 chickens per m² [1] (b) Advantages, any two: less energy lost in movement and keeping warm, so faster growth [1]; large output at lower cost [1]; less land per animal Disadvantages, any two: disease spreads quickly in crowded conditions [1]; waste can pollute water [1]; animal welfare concerns; large amounts of feed needed Examiner insight: “cheaper” on its own is often too vague; link the advantage to energy or output.

5. (a) (4.8 − 4.2) ÷ 4.8 × 100 [1] = 12.5% [1] (b) Any two: more land for crop plants or livestock [1]; land for housing [1]; extraction of natural resources such as timber or minerals (c) Tree roots no longer hold soil, so rain washes it away [1]; fewer trees take up water and transpire [1]; so more water runs off into rivers, causing flooding [1] (d) Fewer trees carry out photosynthesis, so less carbon dioxide is removed [1]; burning or decomposition of felled trees releases carbon dioxide [1] Examiner insight: “explain” needs the mechanism; “trees stop flooding” earns nothing without the link to water uptake or run-off.

6. (a) A resource that is produced as rapidly as it is removed from the environment, so it does not run out [1] (b) Quotas limit the number of trees felled [1]; replanting replaces felled trees, so the forest is not lost [1] (c) Any two: maintain or increase biodiversity [1]; reduce extinction [1]; protect vulnerable ecosystems; maintain ecosystem functions such as nutrient cycling or provision of food, drugs, fuel and genes Examiner insight: the definition in (a) needs the idea of replacement at the same rate as removal; “does not run out” alone is not enough.

7. (a) (9.2 − 2.4) ÷ 9.2 × 100 [1] = 73.9% [1] (b) Fertiliser increases nitrate and other ions in the water [1]; producers such as algae grow rapidly [1]; when producers die, decomposition increases [1]; decomposers carry out more aerobic respiration [1]; this uses up dissolved oxygen [1] (c) Fish die, or move away, because there is too little dissolved oxygen [1] Examiner insight: the fifth mark in (b) depends on linking oxygen loss to decomposers’ respiration; saying the algae use up the oxygen does not earn it.

8. Aquatic: animals become entangled and drown or cannot feed [1]; animals swallow plastic, blocking the gut [1] Terrestrial: plastic is not broken down by decomposers, so it builds up in landfill [1]; animals eat or are trapped by plastic waste [1] Examiner insight: the question names two ecosystems, so a full answer needs points for both; four aquatic points cap the credit.

9. (a) Carbon dioxide: combustion of fossil fuels, or burning forests [1]; methane, any two: cattle or other livestock [1]; rice fields [1]; landfill sites (b) The gases absorb thermal energy that would otherwise leave the Earth [1]; higher concentrations cause an enhanced greenhouse effect [1]; mean global temperature rises, changing the climate, for example rainfall patterns or sea level [1] Examiner insight: the syllabus term is the enhanced greenhouse effect; “the ozone layer” is a different issue and gains no credit.

10. (a) 40 mm: 0.62 × 5 000 = 3 100 [1]; 80 mm: 0.14 × 3 200 = 448 [1] (b) Young fish can escape through the larger mesh [1]; they survive to reproduce, so the population is replaced [1] (c) Any two methods, each with an explanation: quotas limit the mass of fish caught [1], so fewer are removed than are produced [1]; closed seasons stop fishing during breeding [1], so fish can reproduce [1]; protected areas and monitoring are also creditworthy Examiner insight: each method earns a mark and its explanation a second, so a list of four methods with no explanation gets two marks at most.

11. (a) Any three: climate change [1]; habitat destruction [1]; hunting [1]; overharvesting; pollution; introduced species (b) Any two: monitoring and protecting the species and its habitat [1]; education [1]; captive breeding programmes; seed banks, for plants (c) AI: sperm is collected from a male and placed into a female, so animals need not be moved between zoos [1]; IVF: eggs are collected and fertilised by sperm outside the body [1]; the embryos are placed into a female to develop [1] (d) A small population has reduced genetic variation [1]; fewer individuals may have alleles to survive environmental change or disease, so the risk of extinction rises [1] Examiner insight: in (c), stating that IVF happens “inside the female” contradicts the process and loses the mark; “in vitro” means outside the body.

Where marks are usually lost

• Using “pesticide” when the question asks about insecticides or herbicides specifically.
• Leaving out decomposers’ aerobic respiration in eutrophication explanations.
• Dividing by the new value instead of the original value in percentage changes.
• Naming conservation methods without explaining how each lets the population recover.
• Writing “the greenhouse effect” instead of the enhanced greenhouse effect.
• Answering only for aquatic ecosystems when terrestrial effects are asked for as well.
• Defining a sustainable resource without the rate of production matching the rate of removal.

Next steps

• Recap with the Human influences on ecosystems revision notes.
• Reread weak sections in the study guide.
• Browse the Cambridge IGCSE Biology hub and tick off the 0610 checklist.
• Take the Core diagnostic or Extended diagnostic, or try all free 10-minute diagnostics.
• Book a free trial class.

Official syllabus

Cambridge IGCSE Biology 0610 syllabus for examination in 2026, 2027 and 2028 (Version 3), Cambridge University Press & Assessment (Cambridge International Education). Topic 20, sections 20.1 to 20.4.