Mastering Biology Exam 4

Question 1

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that only animals derive their nutrition by

Answer 1

ingesting it

Question 2

What do animals as diverse as corals and monkeys have in common?

Answer 2

presence of Hox genes

Question 3

The last common ancestor of all animals was probably a

Answer 3

flagellated protist.

Question 4

Gastrulation is the process that directly forms the _____.

Answer 4

primary germ layers

Question 5

Which of the following is NOT a characteristic of all animals?

Answer 5

They have tissues, organs, and organ systems.

Question 6

Which of the following animals does NOT have a body cavity?

Answer 6

flatworm

Question 7

During embryological development, the anus forms before the mouth in _____.

Answer 7

humans

Question 8

At which developmental stage should one be able to first distinguish a diploblastic embryo from a triploblastic embryo?

Answer 8

gastrulation

Question 9

At which developmental stage should one be able to first distinguish a protostome embryo from a deuterostome embryo?

Answer 9

cleavage

Question 10

What distinguishes a coelomate animal from a pseudocoelomate animal is that coelomates

Answer 10

have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not.

Question 11

You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?

Answer 11

Muscular activity of its digestive system distorts the body wall.

Question 12

The blastopore denotes the presence of an endoderm-lined cavity in the developing embryo, a cavity that is known as the

Answer 12

archenteron.

Question 13

Protostome characteristics generally include which of the following?

Answer 13

determinate cleavage

Question 14

With the current molecular-based phylogeny in mind, rank the following from most inclusive to least inclusive

Answer 14

3 4 2 1

Question 15

What does recent evidence from molecular systematics reveal about the relationship between grades and clades?

Answer 15

Some, but not all, grades reflect evolutionary relatedness

Question 16

The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of β-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that

Answer 16

the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait.

Question 17

The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of

Answer 17

true tissues

Question 18

Acoelomates are characterized by

Answer 18

a solid body without a cavity surrounding internal organs

Question 19

Which of these is a point of conflict between the phylogenetic analyses presented in Figures 32.10 and 32.11 in your textbook?

Answer 19

the relationship of taxa of segmented animals to taxa of nonsegmented animals

Question 20

What is the key difference between a coelom and a pseudocoelom?

Answer 20

Only a coelom is fully lined with mesoderm tissue.

Question 21

Which feature of deuterostome development explains the formation of identical human twins?

Answer 21

Deuterostomes have indeterminate development.

Question 22

Basal group of animals

Answer 22

Porifera (sponges)

Question 23

Basal group of bilaterates

Answer 23

Acoela