Chapter 33 Homeworks

Which of the following is characteristic of the phylum Platyhelminthes?

They are dorsoventrally flattened

Which of the following is true of annelids? -They perform gas exchange across their skin -They have pseudocoeloms -They have an open circulatory system -They have a gastrovascular cavity -They have a nerve net

They perform gas exchange across their skin

The animal phylum most like the protists that gave rise to the animal kingdom is

Porifera

Nematodes and arthropods are the largest ecdysozoan phyla. Which of the following statements are true?

-Both nematodes and arthropods must molt in order to increase in size -Some nematodes are parasitic on humans -Arthropods possess an open circulatory system -Arthropods are named for their jointed appendages -Both nematodes and arthropods possess an external covering, or cuticle

A marine biologist dredges up a small animal from the bottom of the ocean. It is uniformly segmented, with short, stiff appendages and soft, flexible skin. It has a complete digestive system and a closed circulatory system, plus multiple true coeloms. Based on this, you determine that the animal must be a(n)

Annelid

Members of the phylum Mollusca

Are soft-bodied and often covered by a shell

Which of the following is a characteristic of cnidarians?

Gastrovascular cavity

Which of the following combinations of phylum and description is incorrect? -Nematoda-roundworms, pseudocoelomate -Echinodermata-bilateral symmetry as a larva, coelom present -Platyhelminthes-flatworms, gastrovascular cavity, acoelomate -Cnidaria-radial symmetry, polyp and medusa body forms -Porifera-gastrovascular cavity, coelom present

Porifera-gastrovascular cavity, coelom present

Which of the following are thought to be most closely related to humans?

Sea stars Humans and sea stars are deuterostomes

What evidence suggests that vertebrates are more closely related to echinoderms than are any other invertebrate phyla?

Shared DNA sequences