Question

populations, communities & ecosystems
ecosystem x
13 species of grass
ecosystem y
1 species of grass
a drought strikes both ecosystem x and ecosystem y, but the bison in ecosystem x are better able to survive it. which of the following is a likely explanation?
a. ecosystem y has a greater amount of biomass.
b. the bison in ecosystem x only eat one species of grass.
c. ecosystem x has a greater amount of biodiversity.
d. ecosystem y has a greater amount of biodiversity

Explanation:

Biodiversity refers to the variety of life in a particular ecosystem. Ecosystem X has 13 species of grass while ecosystem Y has only 1. A more biodiverse ecosystem (like X) is more resilient to environmental changes such as drought. With more grass species, if one or some grass species are affected by the drought, the bison in X still have other grass species to feed on. Option A is incorrect as biomass (total mass of organisms) is not the key factor here. Option B would make the bison in X more vulnerable if they only eat one grass species (but X has many). Option D is wrong as Y has low biodiversity.

Answer:

C. Ecosystem X has a greater amount of biodiversity.