21) Which statement about nematodes is most accurate?

A) They are mainly parasites.

B) They are mainly crop pests.

C) They all have straight, flattened bodies.

D) They fit into numerous ecological roles including detritivores.

E) They have exoskeletons made of cellulose.

22) Ticks and horseshoe crabs are members of subphylum:

A) Urochordata.

B) Chelicerata.

C) Crustacea.

D) Insecta.

E) Uniramia.

23) The term “arthropod” best translates as:

A) human-like.

B) outside skeleton.

C) sharp jaws.

D) jointed leg.

E) hairy legs.

24) Which group is most closely related to the echinoderms?

A) Arthropods

B) Molluscs

C) Chordates

D) Nematodes

E) Annelids

25) Which would be a fact supporting the hypothesis that echinoderms such as sea stars evolved into radial symmetry from bilateral symmetry?

A) Their larvae have bilateral symmetry.

B) They use their appendages in a bilateral manner.

C) Their brains show the mirror image development of bilateral symmetry.

D) They swim like animals with bilateral symmetry.

26) Nearly all echinoderms are found in which habitat?

A) lakes

B) rivers

C) beaches

D) ocean surface

E) ocean floor

27) At some point in their lives, all chordates have:

A) jaws.

B) gills.

C) a brain.

D) a dorsal nerve cord.

E) a ventral nerve cord.

28) A notochord is a:

A) tough yet flexible support structure.

B) dorsal nerve cord.

C) ventral nerve cord.

D) specialized tail adapted for swimming.

E) tube for circulating water through gills.

29) Which statement about the vertebrates is most accurate?

A) They are the dominant phylum in the animal kingdom.

B) There are more vertebrate species than flatworms or cnidarians but fewer than there are insects.

C) They are the only group to have evolved aquatic, terrestrial, and flying lifestyles.

D) They evolved from echinoderms.

E) They evolved from molluscs.

30) As part of your independent study in field biology, you are sent to a small, inland sea. In one of your samples, you discover a small eel-like creature. It has a stiff, rod-shaped structure running the length of its dorsal side, with a line of nervous tissue running along with it. You would begin the process of classifying this organism by placing it in phylum:

A) Vertebrata.

B) Arthropoda.

C) Chordata.

D) Cnidaria.

E) Mollusca.