Adult largemouth bass eat smaller fish. These smaller fish eat a variety of foods. They eat some producers (algae) directly. They eat some zooplankton that are primary consumers. They also eat some predatory insects that are secondary consumers. Which option best describes the trophic level(s) of largemouth bass?

a. They are on trophic levels 2–4
b. They are on trophic levels 3–5
c. They are on trophic level 5
d. They are on trophic level 2
e. They are on trophic level 1

b. They are on trophic levels 3–5

Explanation:

The trophic level of an organism represents its position within the food web in an ecosystem.

A food web is defined as a system of interlocking food chains within an ecosystem while food chain in itself is defined as a chain or sequence of transfer of food from one organism to another in an ecosystem.

The first trophic level in a food web contains the producer.

The second trophic level contains the secondary primary consumers.

The third trophic level contains the secondary consumers.

The fourth trophic level contains the tertiary consumers.

The fifth trophic level contains the quaternary consumers.

Small fishes eat producers, primary consumers as well as insects which are secondary consumers while they themselves are eaten by adult largemouth bass.

That small fishes eat producers successfully place them at a minimum level of trophic level two (primary consumer). Feeding on primary consumers means that they can also be at trophic level three (secondary consumer) while feeding on secondary consumers means they can also be at trophic level four as tertiary consumer.

Since adult largemouth do not feed directly on producers, it means their minimum trophic level is three (secondary consumer) and since they feed on smaller fish, it means their maximum level is five (quaternary consumer).

The correct option is b.