The following experiment is used for the following question.

Question

A researcher discovered a species of moth that lays its eggs on oak trees. Eggs are laid at two distinct times of the year: early in spring when the oak trees are flowering and in midsummer when flowering is past. Caterpillars from eggs that hatch in spring feed on oak flowers and look like oak flowers, but caterpillars that hatch in summer feed on oak leaves and look like oak twigs.

How does the same population of moths produce such different-looking caterpillars on the same trees? To answer this question, the biologist caught many female moths from the same population and collected their eggs. He put at least one egg from each female into eight identical cups. The eggs hatched, and at least two larvae from each female were maintained in one of the four temperature and light conditions listed below.

Temperature Day Length
Springlike Springlike
Springlike Summerlike
Summerlike springlike
Summerlike summerlike

In each of the four environments, one of the caterpillars was fed oak flowers, the other oak leaves. Thus, there were a total of eight treatment groups (4 environments × 2 diets).

Which one of the following is not a plausible hypothesis that can be tested in this experiment?

Differences in diet trigger the development of different types of caterpillars.
The longer day lengths of summer trigger the development of twig-like caterpillars.
The cooler temperatures of spring trigger the development of flowerlike caterpillars.
Differences in air pressure, due to differences in elevation, trigger the development of different types of caterpillars.

Answer 1

The hypothesis that is not a plausible hypothesis that can be tested in this experiment is:

Differences in air pressure, due to differences in elevation, trigger the development of different types of caterpillars.

This is because the experiment is designed specifically to manipulate temperature and day length (light conditions), as well as the diet (oak flowers vs. oak leaves) to observe their effects on caterpillar development. Air pressure or elevation is not a factor that is being controlled or tested within the given experimental conditions. The other hypotheses focus on the manipulations that are actually being conducted in the experiment (diet, temperature, and day length), making them testable in this context.