Question

Chemical defenses are an important part of plant-herbivore interactions. The production of these chemical defense compounds results in an energetic cost to the organism. Which of the following statements explains how natural selection resulted in the evolution of these chemical compounds?
The energetic cost of producing chemical compounds is reduced because only small amounts of each chemical are needed to have their desired effects.
The production of chemical compounds requires nitrogen. Nitrogen used to make these compounds cannot be used to make proteins.
Plants produce amino acids that are not incorporated into their own proteins, but herbivorous insects do incorporate these amino acids into their own proteins, rendering the herbivores' proteins nonfunctional.
Individuals that produce chemical compounds are better protected from herbivores and are able to produce more young than individuals that do not produce the compounds.

Answer 1

The correct answer is: Individuals that produce chemical compounds are better protected from herbivores and are able to produce more young than individuals that do not produce the compounds.

Natural selection acts on variations-differences in phenotype that exist among individuals. If a certain trait contribute more to survival and reproduction (individuals with that variant survive more than individuals with other variant), natural selection will favor that trait. In this case, production of chemical compounds is favored over non-producing trait.