Question

A scientist made three observations: (1) in the world’s temperate zones, food is more plentiful in the ocean than it is in fresh water; (2) migratory fish in temperate zones generally mature in the ocean and spawn in fresh water; and (3) migratory fish need much nourishment as they mature but little or none during the part of their lives when they spawn. On the basis of those observations, the scientist formulated the hypothesis that food availability is a determining factor in the migration of migratory fish. Subsequently the scientist learned that in the tropics migratory fish generally mature in fresh water and spawn in the ocean.

Which one of the following would it be most helpful to know in order to judge whether what the scientist subsequently learned calls into question the hypothesis?


(A) whether in the world’s temperate zones, the temperatures of bodies of fresh water tend to be lower than those of the regions of the oceans into which they flow

(B) whether the types of foods that migratory fish eat while they inhabit the ocean are similar to those that they eat while they inhabit bodies of fresh water

(C) whether any species of fish with populations in temperate zones also have populations that live in the tropics

(D) whether there are more species of migratory fish in the tropics than there are in temperate zones

(E) whether in the tropics food is less plentiful in the ocean than in fresh water

Answer 1

To determine if the observation regarding tropical migratory fish calls into question the hypothesis that food availability drives migration patterns, it is essential to know if food is less plentiful in the ocean than in fresh water in the tropics.

Step-by-step explanation:

It appears the original question seeks to understand how the fact that tropical migratory fish generally mature in fresh water and spawn in the ocean might impact the hypothesis that food availability is a determining factor in the migration patterns of migratory fish. This differs from temperate migratory fish, which typically mature in the ocean and spawn in fresh water, presumably because food is more plentiful in the ocean in temperate zones.

To assess the impact of the observation in tropical regions on the hypothesis, it would be helpful to know (E) whether in the tropics food is less plentiful in the ocean than in fresh water. If food is indeed less plentiful in the ocean, this would support the hypothesis that food availability is crucial for determining migration patterns, as tropical fish would be migrating towhere food is more plentiful to mature. However, if food is more plentiful or equally available in both environments, this might suggest other factors are influencing migratory behavior.

Overall, the understanding of migratory patterns is complex and can be influenced by a variety of factors including food availability, temperature, and habitat suitability.