Science Assessment ~ Topics ~ Interdependence in Ecosystems ~ Item IE031006 ~ 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 will be fewer Ls to eat the Ms, so there will be more Ms to eat the Ns.
The number of Ns will decrease because there will be fewer Ls for the Ms to eat, so there will be fewer Ms available for the Ns to eat.
The number of Ns will not change because the Ls are killed, not the Ns.
The number of Ns will not change because Ns are not connected to Ls in the diagram.

Distribution of responses
Answer Choice		Overall	Grades		Gender		Primary Language
		n = 2821	6–8 n = 1608	9–12 n = 1208	Male n = 1364	Female n = 1416	English n = 2591	Other n = 170
A.	The number of Ns will decrease because there will be fewer Ls to eat the Ms, so there will be more Ms to eat the Ns.	18%	20%	15%	15%	20%	18%	14%
B.	The number of Ns will decrease because there will be fewer Ls for the Ms to eat, so there will be fewer Ms available for the Ns to eat.	67%	63%	72%	69%	65%	67%	59%
C.	The number of Ns will not change because the Ls are killed, not the Ns.	9%	10%	8%	10%	8%	9%	12%
D.	The number of Ns will not change because Ns are not connected to Ls in the diagram.	7%	8%	5%	7%	7%	6%	15%

Science Assessment

Item IE031006: Changes in a population in a food web can affect other populations of organisms even if they are not directly connected in a feeding relationship (no specific organisms identified).