50) To be characterized as a chordate, an organism must
A) display all four key characteristics of Chordata in both the larval and adult stages.
B) possess a backbone in at least one life stage.
C) possess a backbone in both the larval and adult stages.
D) display each of the four key characteristics of the chordates at some point in the life cycle.
51) Which of the following statements about tunicates indicates that these animals are chordates?
A) Larvae show segmentation, radial symmetry, and a pseudocoelom.
B) Larvae have a dorsal hollow nerve cord, a post-anal tail, pharyngeal slits, and a notochord.
C) Larvae and adults both have a true coelom.
D) Tunicates have tube feet and a water vascular system.
52) You find a small, elongated animal embedded in the sand with one end sticking out. Among
other things, it has segmental musculature, a coelom, a notochord, and a complete digestive tract
with an anus located partway down the body. This animal is
A) an annelid.
B) a larval echinoderm.
C) either a larval echinoderm or a chordate.
D) a chordate.
53) Traditional animal phylogenetic trees and the most recent molecular phylogenetic trees have
many similarities. Which is a feature of the recent trees that was not present in the traditional
phylogeny?
A) the placement of Echinodermata and Chordata together in a clade of deuterostomes
B) the status of sponges as the first group to diverge from the other animals
C) the grouping of nematodes and arthropods into a clade called the Ecdysozoa
D) the grouping of all bilaterally symmetric animals within a single clade