Science Assessment ~ Topics ~ Interdependence in Ecosystems ~ Item IE025005 ~ Student Performance

The diagram below shows the feeding relationships between populations of organisms L, M, N, O, P, Q, R, and S in an area. 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 populations of organisms could be affected if the number of Ps changes?

Only the population of Ps could be affected.
Only the populations of Ls, Ns, and Ss could be affected.
Only the populations of Ps, Qs, Ss, and Rs could be affected.
The populations of all of the organisms shown in the diagram could be affected.

Distribution of responses
Answer Choice		Overall	Grades		Gender		Primary Language
		n = 1469	6–8 n = 856	9–12 n = 611	Male n = 691	Female n = 761	English n = 1329	Other n = 104
A.	Only the population of Ps could be affected.	6%	5%	6%	6%	6%	5%	11%
B.	Only the populations of Ls, Ns, and Ss could be affected.	11%	11%	11%	13%	10%	11%	13%
C.	Only the populations of Ps, Qs, Ss, and Rs could be affected.	32%	33%	30%	30%	33%	31%	40%
D.	The populations of all of the organisms shown in the diagram could be affected.	51%	50%	53%	51%	51%	52%	37%

Science Assessment

Item IE025005: 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 (no specific organisms identified).