Ch 32

Question 1

What are the defining characteristics of animals?

Answer 1

Multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers

Question 2

How do animals obtain their nutrients?

Answer 2

Animals ingest food and then digest it internally

Question 3

What is the structural support of animal cells provided by?

Answer 3

Structural proteins such as collagen

Question 4

What are the unique, defining characteristics of animals?

Answer 4

Nervous tissue and muscle tissue

Question 5

What type of reproduction do most animals undergo?

Answer 5

Sexually, with the diploid stage usually dominating the life cycle

Question 6

What is cleavage in animal development?

Answer 6

A succession of cell division without growth between divisions

Question 7

What is a blastula?

Answer 7

A hollow ball of cells formed during early embryonic development

Question 8

What is gastrulation?

Answer 8

The process that transforms the blastula into a gastrula with different layers of embryonic tissues

Question 9

What is a larva?

Answer 9

A sexually immature stage that is morphologically and behaviorally distinct from the adult stage

Question 10

What are Hox genes?

Answer 10

A unique family of regulatory genes that control the expression of many other genes influencing morphology

Question 11

How long has the history of animals been established?

Answer 11

More than half a billion years

Question 12

What is the estimated number of living animal species?

Answer 12

1.3 million, with many more estimated to exist

Question 13

What are choanoflagellates?

Answer 13

The closest living relatives to animals

Question 14

What is body symmetry?

Answer 14

A characteristic used to compare animals, which can be radial or bilateral

Question 15

Define radial symmetry.

Answer 15

Body parts are arranged around a single central axis

Question 16

Define bilateral symmetry.

Answer 16

Body parts are arranged around two axes of orientation

Question 17

What are the two germ layers in most animals?

Answer 17

Ectoderm and endoderm

Question 18

What additional germ layer do triploblastic animals have?

Answer 18

Mesoderm

Question 19

What is a coelom?

Answer 19

A body cavity surrounded by tissues derived from mesoderm

Question 20

What is a hemocoel?

Answer 20

A body cavity formed between the mesoderm and endoderm filled with hemolymph

Question 21

What are the two developmental modes of animals?

Answer 21

Protostome development and deuterostome development

Question 22

What type of cleavage do protostome development animals exhibit?

Answer 22

Spiral and determinant cleavage

Question 23

What type of cleavage do deuterostome development animals exhibit?

Answer 23

Radial and indeterminate cleavage

Question 24

What does the blastopore become in protostome development?

Answer 24

The mouth

Question 25

What does the blastopore become in deuterostome development?

Answer 25

The anus

Question 26

What is the clade Eumetazoa?

Answer 26

A clade of animals with tissues

Question 27

Which phylum includes vertebrates?

Answer 27

Chordata

Question 28

What are ecdysozoans known for?

Answer 28

Secreting an external skeleton (exoskeleton) and undergoing ecdysis

Question 29

What is the lophophore?

Answer 29

A crown of ciliated tentacles used for feeding in some lophotrochozoans

Question 30

What ongoing questions are current focuses of research in animal systematics?

Answer 30

Are ctenophores basal metazoans? Are acoelomate flatworms basal bilaterians?