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Item ID017006: Changes in a population may affect populations that are not directly connected by a feeding relationship even if they are several steps away in a food web (woodland ecosystem).

The diagram below shows the feeding relationships between populations of plants and animals in an area. The arrows point from the organisms being eaten to the organisms that eat them.

A new species that eats only mice becomes part of this food web, greatly reducing the number of mice in this area. Using only the relationships between the plants and animals shown in the diagram, which of the following would decrease? You can assume that the number of foxes stays the same and that no other organisms leave or enter the area.

  1. The number of robins would decrease.
  2. The amount of grass would decrease.
  3. The number of caterpillars would decrease.
  4. Only the number of mice would decrease.
Distribution of Responses
Chart showing distrubtion of responses for Item IE017006
Students Responding Correctly
Group Correct Total Percent
Overall 326 1392 23%
  6–8 158 785 20%
  9–12 168 605 28%
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