Chapter 17

The first animals ___________. a. arose during the Cambrian b. had an embryo with three tissue layers c. lived in the sea d. had an open circulatory system.

The colonial hypothesis of animal origins states that ______________. a. animals colonized the land during the Cambrian b. animals evolved from a colonial protist c. the earliest animals lived in colonies d. most animals live in social groups

A ________ functions in both digestion and gas exchange. a. pseudocoelom b. coelom c. complete digestive tract d. gastrovascular cavity

Most animals have a body that is ___________. a. radially symmetrical b. bilaterally symmetrical c. asymmetrical

Earthworms are most closely related to _______________. a. insects b. tapeworms c. leeches d. roundworms

The _________ include the only winged invertebrates. a. flatworms b. annelids c. arthropods d. cnidarians

All modern fishes have ______________. a. jaws b. a cartilage skeleton c. scales d. a closed circulatory system

All vertebrates are _________, but only some are ____________. a. tetrapods; mammals b. chordates; amniotes c. amniotes; hominins d. bipedal; australopiths

Amniote eggs ______________. a. enclose a developing embryo inside multiple membranes b. are typically released into water c. define the protostome lineage d. allowed the first tetrapods to move onto land

Birds and placental mammals __________. a. are endotherms b. are descended from dinosaurs c. have mammary glands d. have an open circulatory system

True or false? Bipedalism is the defining trait of primates.

Homo erectus is a likely ancestor of \(H .\) sapiens and ________. a. Homo habilis b. australopiths c. the great apes d. Neanderthals

Match the organisms with the appropriate description. $$ \text {sponges} \quad \quad \text {a. most diverse vertebrates} $$ $$ \text {cnidarians} \quad \quad \text {b. no true tissues, no organs} $$ $$ \text {flatworms} \quad \quad \text {c.jointed exoskeleton} $$ $$ \text {roundworms} \quad \quad \text {d. mantle over body mass} $$ $$ \text {annelids} \quad \quad \text {e. segmented worms} $$ $$ \text {arthropods} \quad \quad \text {f. tube feet, spiny skin} $$ $$ \text {mollusks} \quad \quad \text {g. have specialized stinging cells} $$ $$ \text {echinoderms} \quad \quad \text {h. lay amniote eggs} $$ $$ \text {amphibians} \quad \quad \text {i. feed young secreted milk} $$ $$ \text {fishes} \quad \quad \text {j. unsegmented, molting worms} $$ $$ \text {birds} \quad \quad \text {k. first terrestrial tetrapods} $$ $$ \text {mammals} \quad \quad \text {l. tailless primates} $$ $$ \text {apes} \quad \quad \text {m. bilateral with a saclike gut} $$

Arrange the events in order, from most ancient to most recent. a. Cambrian explosion of diversity b. Origin of animals c. Tetrapods move onto the land d. Extinction of dinosaurs e. Homo erectus leaves Africa f. First jawed vertebrates evolve