# A hedgerow ecosystem contains the following organisms: bramble plants, aphids, ladybirds, blue tits, and sparrowhawks. Describe how a significant reduction in the number of aphids would affect the populations of blue tits and sparrowhawks. Give a reason for each effect.

> Cambridge International IGCSE Biology (0610) — 19.2 Food chains and food webs · Describe · 4 marks

## Mark scheme (4 marks)

1. Blue tit population decreases / falls
2. Because blue tits have less food available (as aphids are their food source / prey)
3. Sparrowhawk population decreases / falls
4. Because sparrowhawks have less food available as blue tit numbers have fallen / sparrowhawks depend on blue tits as a food source

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