Science Assessment ~ Topics ~ Interdependence in Ecosystems ~ Item IE032004 ~ Student Performance

The diagram below shows the feeding relationships between populations of organisms L, M, and N. The arrows point from the organisms being eaten to the organisms that eat them.

Using only the relationships between the organisms shown in the diagram, which of the following statements describes what will happen to the number of Ns if most of the Ls are killed and why?

The number of Ns will decrease because there are more Ms to eat them.
The number of Ns will decrease because there will be fewer Ms for them to eat.
The number of Ns will not change because Ns are not connected to Ls in the diagram.
More information is needed to tell what will happen to the number of Ns.

Distribution of responses
Answer Choice		Overall	Grades		Gender		Primary Language
		n = 2797	6–8 n = 1536	9–12 n = 1253	Male n = 1323	Female n = 1407	English n = 2456	Other n = 270
A.	The number of Ns will decrease because there are more Ms to eat them.	15%	17%	13%	14%	16%	15%	15%
B.	The number of Ns will decrease because there will be fewer Ms for them to eat.	61%	56%	68%	64%	58%	62%	55%
C.	The number of Ns will not change because Ns are not connected to Ls in the diagram.	13%	15%	10%	11%	15%	13%	17%
D.	More information is needed to tell what will happen to the number of Ns.	11%	13%	9%	11%	11%	11%	13%

Science Assessment

Item IE032004: Changes in a population in a food web can affect populations of other organisms even if they are not directly connected in a feeding relationship (no specific organisms identified).