The following questions refer to the paragraph below.
An elementary school science teacher decided to liven up the classroom with a salt-water aquarium. Knowing that salt-water aquaria can be quite a hassle, the teacher proceeded stepwise. First, the teacher conditioned the water. Next, the teacher decided to stock the tank with various marine invertebrates, including a polychaete, a siliceous sponge, several bivalves, a shrimp, several sea anemones of different types, a colonial hydra, a few coral species, an ectoproct, a sea star, and several gastropod varieties. Lastly, some vertebrates-a parrotfish and a clownfish-were added. She arranged for daily feedings of copepods and feeder fish.
-The clownfish readily swims among the tentacles of the sea anemones; the parrotfish avoids them. One hypothesis for the clownfish's apparent immunity is that they slowly build a tolerance to the sea anemone's toxin. A second hypothesis is that a chemical in the mucus that coats the clownfish prevents the nematocysts from being triggered. Which of the following graphs supports the second, but not the first, of these hypotheses?

Question

Quizplus · Accepted Answer

Graph C shows that the mucus from the clownfish prevents the nematocysts from triggering, as there is no effect on the stinging response when the mucus extract is added to the sea anemone. However, there is an effect on the stinging response when the sea anemone extract is added to the mucus, supporting the idea that the mucus protects the clownfish. This graph does not support the first hypothesis about the clownfish building up a tolerance to the toxin, as there is no mention of repeated exposure or a change in response over time.

The Following Questions Refer to the Paragraph Below