Chapter 32 - Overview of Animal Diversity

Question 1

What are animals?

Answer 1

multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers

Question 2

What kinds of tissues are unique to animals?

Answer 2

Nervous tissue and muscle tissue

Question 3

What do animals’ cells have instead of cell walls?

Answer 3

Structural proteins like collagen

Question 4

What is cleavage?

Answer 4

When a zygote undergoes rapid cell division after fertilization

Question 5

What does cleavage lead to?

Answer 5

the formation of a multicellular, hollow blastula

Question 6

What is gastrulation?

Answer 6

when a blastula forms a gastrula with different layers of embryonic tissues

Question 7

What is a larva?

Answer 7

sexually immature and morphologically distinct from the adult stage of animal development

Question 8

What is a juvenile?

Answer 8

the stage of animal development when it resembles an adult, but is not sexually mature yet

Question 9

What are Hox genes?

Answer 9

genes that regulate the development of body form

Question 10

How are choanoflagellates and animals similar?

Answer 10

They have sequence similarities in the genes involved in adherence and attachment that were required with the advent of multicellularity.

Question 11

What was the Cambrian explosion?

Answer 11

the earliest fossil appearance of animals

Question 12

List the characteristics of bilaterians

Answer 12

Bilaterally symmetric form, complete digestive tract, one-way digestive system

Question 13

What is a body plan?

Answer 13

a set of morphological and developmental traits that is used to categorize animals

Question 14

What is radial symmetry?

Answer 14

when animals have a top and a bottom but no front, back, left, or right; the type of symmetry found in a flowerpot

Question 15

What is bilateral symmetry?

Answer 15

when animals have a dorsal (top) side and a ventral (bottom) side, a right side, a left side, an anterior (front) and a posterior (back)

Question 16

Compare the movements of radially and bilaterally symmetrical animals.

Answer 16

Radial animals are sessile or planktonic; they drift or swim weakly. Bilateral animals move actively and heave a central nervous system.

Question 17

What are tissues?

Answer 17

collections of specialized cells isolated from other tissues by membranous layers

Question 18

How are tissues formed?

Answer 18

From three germ layers during development

Question 19

What is the ectoderm?

Answer 19

the germ layer covering the embryo’s surface

Question 20

What is the endoderm?

Answer 20

the innermost germ layer lining the archenteron (developing digestive tube)

Question 21

What are diploblastic animals?

Answer 21

Animals with only an ectoderm and an endoderm

Question 22

What are triploblasic animals?

Answer 22

animals that have an ectoderm, an endoderm, and a mesoderm; includes all bilaterally symmetrical animals

Question 23

What is a mesoderm?

Answer 23

an intermediate tissue layer between the ectoderm and the endoderm

Question 24

What is a coelom?

Answer 24

a true body cavity, derived from the mesoderm

Question 25

What are coelomates?

Answer 25

animals with a true coelom (body cavity)

Question 26

What is a pseudocoelom?

Answer 26

a false body cavity that isn't lined on both sides because its derived from the mesoderm and the endoderm

Question 27

What are pseudocoelomates?

Answer 27

triploblastic animals with a pseudocoelom

Question 28

What are acoelomates?

Answer 28

triploblastic animals that lack a body cavity

Question 29

What are the functions of a body cavity?

Answer 29

Fluid cushions suspended organs; fluid acts like a skeleton against which the muscles can work; Enables internal organs to grow and move independently of the outer body wall

Question 30

What is a grade?

Answer 30

a group whose members share key biological features

Question 31

What is a clade?

Answer 31

a group consisting of an ancestor and all of its descendants

Question 32

What happens in protostome development?

Answer 32

the cleavage is spiral and determinate

Question 33

What is a determinate cleavage?

Answer 33

when the developmental fate of embryonic cells is determined early in development

Question 34

What is deuterostome development?

Answer 34

the cleavage is radial and indeterminate

Question 35

What is an indeterminate cleavage?

Answer 35

when each cell in the early stage of cleavage retains the capacity to develop into a complete embryo; makes identical twins and embryonic stem cells possible

Question 36

What is the difference in coelom formation between protostomes and deuterostomes?

Answer 36

In protostomes, the splitting of solid masses of the mesoderm forms the coelom; in deuterostomes, the mesoderm buds from the wall of the archenteron to form the coelom

Question 37

What does the blastopore do?

Answer 37

Connects the archenteron to the exterior of the gastrula

Question 38

When is the blastopore formed?

Answer 38

during gastrulation

Question 39

What is eumetazoa?

Answer 39

the clade of animals with tissues; "true animals"

Question 40

What is the only clade of bilaterian animals that includes vertebrates?

Answer 40

Chordata

Question 41

What are invertebrates?

Answer 41

animals that lack a backbone

Question 42

What are vertebrates?

Answer 42

animals with a backbone

Question 43

What are the three clades of bilaterians?

Answer 43

Deuterostomia, Ecdysozoa, and Lophotrochozoa

Question 44

Which clade of bilaterians includes vertebrates and invertebrates?

Answer 44

Deuterostomia

Question 45

Which clade of bilaterians secretes external skeletons?

Answer 45

Ecdysozoa

Question 46

What is ecdysis?

Answer 46

when Ecdysozoans shed their exoskeletons

Question 47

Which clades of bilaterians only have invertebrates?

Answer 47

Ecdysozoa and Lophotrochozoa

Question 48

What is a lophophore?

Answer 48

a feeding structure

Question 49

What bilaterian clade can undergo the trochophore larva stage?

Answer 49

Lophotrochozoa