1 The diagram shows a photomicrograph of the lower surface of a leaf. B C A (a) (i) Name each of the parts labelled A to C. cell A … cell B … pore C … [3] (ii) In an area affected by air pollution, the surface of the leaf becomes covered with particles. These particles reduce the amount of light entering the leaf and may block all pores of the type labelled C. Explain how this will affect the production of starch by the plant. … … … … … … … … [4] (b) A species of caterpillar, the holly looper, feeds on the leaves of the holly plant. Holly plants produce red berries that are eaten by a species of bird, the song thrush. Song thrushes also eat caterpillars and are eaten by hawks. (i) Use the information above to: • Complete the food web below by writing the name of one species in each box. • Draw arrows between the boxes to show the direction of energy flow between organisms. … … … holly [2] (ii) State, for the food web above, the number of: species that are producers … species that are consumers … trophic levels. … [3] [Total: 12]

1(a)(i) (cell A) epidermis / epidermal ; (cell B) guard ; (pore C) stoma / stomata / stomatal pore ; 3 1(a)(ii) less/no CO2 + entry ; less/no light absorbed by + chlorophyll / chloroplasts ; less/no photosynthesis ; less/no glucose / sugar / carbohydrate + produced ; less/no starch produced ; 4 1(b)(i) all organisms correct ; all arrows correct ; 2 1(b)(ii) (producers) 1 / holly ; (consumers) 3 / holly looper + song thrush + hawk ; (trophic levels) 4 ; 3

3 A sycamore tree is a producer for many food chains in a forest ecosystem. (a) Explain what is meant by: (i) a producer … … [1] (ii) a food chain. … … [1] (b) The diagrams show a pyramid of numbers and a pyramid of biomass for a sycamore tree. birds of prey birds insects tree pyramid of numbers pyramid of biomass Explain the different shapes of the two pyramids. … … … … … … … [4] (c) Sycamore trees produce flowers that are insect-pollinated. Suggest two features of flowers which adapt them for insect-pollination. 1 … 2 … [2] (d) State the type of cell division that produces pollen grains. … [1] [Total: 9]

3(a)(i) photosynthesis / autotrophic / making own organic nutrients ; 1 3(a)(ii) flow / transfer + energy / food ; 1 3(b) any four from: biomass tree has large mass so long rectangle / correct reference to relative masses at two trophic levels ; biomass declines as trophic level increases ; numbers there is only one tree so a short rectangle for numbers / correct reference to relative numbers at two trophic levels ; both or either after producer both pyramids in shape ; energy is lost (to the environment) ; as heat / thermal energy ; from respiration ; 4 3(c) any two from: large / colourful + petals / sepals ; nectaries / nectar ; scent ; anthers / stigma + inside petals / short / sticky stigma ; markings / nectar guides / petals modified with insect landing site ; pollen rough / sticky ; 2 3(d) meiosis ; 1

4 The kapok tree is a flowering plant that grows rapidly to become one of the tallest trees in a tropical rainforest ecosystem. Climbing plants wind up its stem and the tree provides a habitat for insect-eating birds and frogs. Bats feed on the nectar from its flowers and pollinate them so they can produce small, light seeds. Insects feed on its leaves and when the leaves fall to the ground they will come into contact with soil bacteria and fungi. (a) (i) Use the information provided to draw a food chain for this tropical rainforest in the space provided. The chain should contain three organisms. [2] (ii) Suggest and explain ways in which being tall may be helpful for the survival of this tree species. … … … … [3] (iii) Explain why the bacteria and fungi found in the rainforest soil are important in this ecosystem. … … … … [3] (b) Every year large areas of tropical rainforest are destroyed by burning. A large percentage of the mass of a kapok tree is made of the element carbon. (i) Name one substance, found in plants but not in animals, that contains carbon. … [1] (ii) Explain how burning trees contributes to global warming. … … … … [2] [Total: 11]

4(a)(i) kapok / tree + insect + frog / bird ; arrow in correct direction from kapok / tree / leaves / plant at start ; 2 4(a)(ii) any three from: gets light / reduced + competition for light ; photosynthesis ; exposed to wind ; for seed dispersal ; easier for bats to find flowers ; 3 4(a)(iii) any three from: decomposition / decay / decomposers / break down (organic matter) ; use of enzymes ; carbon / nitrogen / nutrients + recycled / returned to soil ; carbon / nitrogen / named nutrient used by plants ; 3 4(b)(i) starch / cellulose / chlorophyll / sucrose ; 1 4(b)(ii) any two from: releases carbon dioxide / carbon dioxide into the atmosphere ; greenhouse gas ; traps thermal energy / causes temperature to increase ; removal of carbon sink AW ; 2

5 A farmer is using a tool, called a mattock, to weed her crop. right arm (a) Explain how the muscles and bones in her right arm help her to lift the tool. … … … … … … [4] (b) The farmer has not used any insecticides or artificial fertilisers on the crop. Explain ways in which this may help the local environment. … … … … … … [4] [Total: 8]

5(a) any four from: named bone(s) + location ; antagonistic muscles ; biceps contract ; become shorter / radius or ulna is moved towards humerus ; triceps relax ; hinge joint ; 4 5(b) any four from: no leaching / run-off into water / water pollution ; so insecticides not ingested by aquatic insects ; no bioaccumulation AW ; (so fertilisers) don’t cause algal bloom / eutrophication ; eutrophication detail e.g. decomposition of algae / lack of oxygen / increase in bacteria ; pollinators / insects that eat pests can still function ; increase biodiversity ; greater variety of food sources for consumers ; if artificial fertilisers replaced with organic then soil structure maintained AW ; 4

9 Which row shows factors that may contribute to famine? climate change causing drought destruction of tropical forest flooding increased human population increased use of fertilisers A yes yes yes no no B yes no yes yes no C no yes no yes yes D yes no no yes yes

Answer: B To earn the mark, a student must correctly identify climate change causing drought, flooding, and increased human population as factors contributing to famine.

Cambridge O Level Biology · 5090

O-Level Biology (5090) Relationships of organisms with one another and with the environment past paper questions

Revise O-Level Biology (5090) — Relationships of organisms with one another and with the environment 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.

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

Relationships of organisms with one another and with the environment in O-Level Biology 5090 exams, 2020–2025

Across 2020–2025, Relationships of organisms with one another and with the environment accounted for 140 questions worth 651 marks in Cambridge O Level Biology (5090) papers.

By year
Year	Questions	Marks
2020	22	79
2021	26	89
2022	20	100
2023	24	109
2024	25	148
2025	23	126

Most-tested subtopics

19.4 Effects of humans on ecosystems294 marks
19.3 Ecosystems and biodiversity206 marks
19.1 Energy flow204 marks

Appears in

Paper 1 · 92 qs
Paper 2 · 40 qs
Paper 3 · 5 qs
Paper 4 · 3 qs

All most-tested Biology topics

2021 Oct/Nov · Paper 2 · Q1 · 12 marks
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2021 May/Jun · Paper 2 · Q3 · 9 marks
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2021 Oct/Nov · Paper 2 · Q4 · 11 marks
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2021 May/Jun · Paper 2 · Q5 · 8 marks
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2021 May/Jun · Paper 1 · Q9 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q9
Answer: B
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