The following questions refer to the paragraph below.
A farm pond, usually dry during winter, has plenty of water and aquatic pond life during the summer. One summer, Sarah returns to the family farm from college. Observing the pond, she is fascinated by some six-legged organisms that can crawl about on submerged surfaces or, when disturbed, seemingly "jet" through the water. Watching further, she is able to conclude that the "mystery organisms" are ambush predators, and their prey includes everything from insects to small fish and tadpoles.
-In a tide pool, a student encounters an organism with a hard outer covering that contains much calcium carbonate, an open circulatory system, and gills. The organism could potentially be a crab, a shrimp, a barnacle, or a bivalve. Which structure below would allow for the most certain identification?
A)a mantle
B)a heart
C)a body cavity
D)a lophophore
E)eyes

Question

Quizplus · Accepted Answer

The mantle is a unique structure found in mollusks (such as bivalves) that secretes the shell and also helps with respiration and excretion. Therefore, the presence of a mantle would allow for the certain identification of a bivalve. The other structures listed (heart, body cavity, lophophore, and eyes) are found in a variety of different aquatic organisms and would not provide as strong of an identification.

The Following Questions Refer to the Paragraph Below