8. The population sizes of different species of Darwin's finches have varied since records of their
numbers have been kept. The drawings show several different species of the finches and their beaks.
Darwin's finches live in the same habitat and are subject to the same environmental pressures. Yet, as
one population size increases, another decreases, and then the reverse may occur. Which stimulus is
MOST likely to cause these changes in population size?
A) a decrease in nesting materials
B) changes in the predator population
C) a loss of habitat due to human encroachment
D) changes in the size and hardness of available seed food

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.

answer; hydrologic cycle;