A ranger photographed the organisms shown in Fig. 1 beside a mountain stream. Dippers eat mayfly larvae, and trout eat both mayfly larvae and dippers. Algae...
Question 1 Report
A ranger photographed the organisms shown in Fig. 1 beside a mountain stream. Dippers eat mayfly larvae, and trout eat both mayfly larvae and dippers. Algae grow on submerged stones. During a hot summer, the stream level fell and some stones were no longer covered by water.
(a) State one food chain from Fig. 1 that contains four organisms. [2]
(b) Explain why algae are important to this food web. [2]
(c) Suggest how the lower stream level could affect the number of trout. [2]
Answer Details
(a) A four-organism food chain is:
algae → mayfly larva → dipper → trout [2]
The arrows show energy transfer from food to consumer.
(b) Algae are producers. They capture light energy and convert it into food or biomass, providing energy for consumers in the food web. [2]
(c) Trout numbers may decrease. A lower water level can reduce algae and thus reduce food through the web, or it can reduce available aquatic habitat for trout. [2]
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