Chapter 16

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

List the four distinguishing chordate traits. Which of these traits are retained by an adult tunicate?

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

Arrange the events in order, from most ancient to most recent. 1 2 3 4 5 6 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