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CIE iGCSE Co-Ordinated Science B18.2 Food chains and food webs Exam Style Questions Paper 3

CIE iGCSE Co-Ordinated Science Paper 3 - All Chapters

Question

(a) Fig. 4.1 shows a food web.
(i) Identify one herbivore shown in Fig. 4.1.
(ii) Identify one secondary consumer shown in Fig. 4.1.
(iii) State the number of producers shown in Fig. 4.1.
(b) Fig. 4.2 is a diagram of an insect-pollinated flower.
Using letters A-G in Fig. 4.2, identify the part:
that produces the female gametes …………..
that produces the pollen grains …………..
where pollination takes place …………..
(c) Flowers produce seeds.
State the three conditions needed for germination of seeds.

Most-appropriate topic codes (Cambridge IGCSE Coordinated Sciences 0654):

• Topic B18.2 — Food chains and food webs (Part (a)(i), (a)(ii), (a)(iii))
• Topic B15.3 — Sexual reproduction in plants (Part (b))
• Topic B15.3 — Sexual reproduction in plants (Part (c))

▶️ Answer/Explanation

(a)(i) giraffe / elephant / zebra
Herbivores are animals that eat only plants. In the food web, giraffes, elephants, and zebras are all primary consumers that feed directly on producers (plants).

(a)(ii) cheetah / lion / hyena
Secondary consumers eat primary consumers. Cheetahs, lions, and hyenas are predators that feed on herbivores such as zebras and giraffes.

(a)(iii) 4
Producers are organisms that make their own food through photosynthesis. The food web shows four producers: the tree, shrub, grass, and plant.

(b) E; G; B
The ovary (E) contains ovules which produce female gametes. The anther (G) produces pollen grains containing male gametes. Pollination occurs on the stigma (B), where pollen lands and germinates.

(c) oxygen; suitable temperature; water
Seeds require oxygen for aerobic respiration, a suitable temperature for enzyme activity, and water for metabolic processes and to soften the seed coat.

Question

(a)(i) Fig. 4.1 shows an example of habitat destruction.
Fig 4.1 Habitat destruction
The trees have been removed to create an area for housing. Describe two other reasons for habitat destruction by humans.
(a)(ii) Habitat destruction can cause species to become endangered. Describe two ways in which an endangered species can be conserved.
(b)(i) Fig. 4.2 shows a food web.
Fig 4.2 Food web
Use Fig. 4.2 to construct a complete food chain that includes the frog.
……………….. $\rightarrow$ ……………….. $\rightarrow$ ……………….. $\rightarrow$ ……………….. $\rightarrow$ ………………..
(b)(ii) Table 4.1 shows some terms that can be used to describe some of the organisms in Fig. 4.2. Complete Table 4.1 by placing ticks $(\checkmark)$ in the boxes to show the terms that describe each organism.
Table 4.1 organism terms

Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):

• Topic B19.1 — Habitat destruction (Part (a)(i))
• Topic B19.2 — Conservation (Part (a)(ii))
• Topic B18.2 — Food chains and food webs (Part (b)(i) & (b)(ii))

▶️ Answer/Explanation

(a)(i)
1. Clearing land for agriculture / crop production
2. Extraction of natural resources (e.g. mining, quarrying, or logging for timber)
Other acceptable answers: livestock farming, building roads or factories, urban expansion.
Human activities that convert natural land for food production or resource extraction destroy the structural complexity of habitats, removing shelter and food sources that many species depend upon for survival and reproduction.

(a)(ii)
1. Captive breeding programmes — breeding endangered species in zoos or sanctuaries and reintroducing them into protected habitats.
2. Protecting habitats — establishing nature reserves or national parks where species and their environments are legally protected.
Captive breeding helps increase population numbers and maintain genetic diversity when wild populations are critically low. Habitat protection addresses the root cause of endangerment by ensuring that suitable environments remain available for species to survive and reproduce naturally.

(b)(i)
grass $\rightarrow$ grasshopper $\rightarrow$ frog $\rightarrow$ snake $\rightarrow$ hawk
(Also acceptable: grass $\rightarrow$ grasshopper $\rightarrow$ frog $\rightarrow$ owl)
Each arrow in a food chain represents the transfer of energy from the organism being eaten to the organism eating it. The chain must begin with a producer (grass) and include the frog as an intermediate consumer, with at least one organism feeding on it above.

(b)(ii)
Completed Table 4.1
Producers make their own food via photosynthesis (grass); herbivores eat only plants (grasshopper); carnivores eat only animals (snake). Primary consumers feed directly on producers, secondary consumers feed on primary consumers, and tertiary consumers feed on secondary consumers — each level representing a step up the food chain.

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