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Problem 1
One of the characteristics unique to animals is a. gastrulation. b. multicellularity. c. sexual reproduction. d. flagellated sperm.
Problem 2
The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of a. a body cavity. b. a complete digestive tract. c. mesoderm. d. tissues.
Problem 3
Which of the following was probably an important factor in bringing about the Cambrian explosion? (A) the movement of animals onto land (B) an increase in the concentration of atmospheric nitrogen (C) the emergence of predator-prey relationships (D) the origin of bilaterian animals
- Which of the following combinations of phylum and description is correct? (A) Echinodermata—radial symmetry as a larva, coelom (B) Nematoda—roundworms, internal skeleton (C) Platyhelminthes—flatworms, gastrovascular cavity, no body cavity (D) Porifera—gastrovascular cavity, coelom
Problem 4
Problem 4
Based on the tree in Figure 32.11, which statement is true?
A. The animal kingdom is not monophyletic.
B. The Acoela are more closely related to echinoderms than to annelids.
C. Sponges are basal animals.
D. Bilaterians do not form a clade.
