ch 32 hw

Which of the following statements is correct?

All animals share a common ancestor.

Body symmetry in animals affects swimming in which of the following ways?

Bilaterally symmetric animals can be streamlined for swimming, but radially symmetric animals cannot.

The earliest ancestors of about half of all extant animal phyla can be traced back to the __________ explosion.

Cambrian

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

Chordates

Which of these statements, if accurate, would support the claim that the ancestral cnidarians had bilateral symmetry?

Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects.

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

Deuterostomes have indeterminate development.

The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups-Lophotrochozoa and Ecdysozoa. What does this finding suggest?

Division of these two groups occurred after the protostome developmental sequence appeared.

You find a new species of worm and want to classify it. Which of the following lines of evidence would allow you to classify the worm as a nematode and not an annelid?

It sheds its external skeleton to grow.

A graduate student finds an organism in a pond and thinks it is a freshwater sponge. A postdoctoral student thinks it looks more like an aquatic fungus. How can they decide whether it is an animal or a fungus?

Look for cell walls under a microscope.

Which of the following characteristics in an organism would indicate that lacks a coelom?

Muscular activity of its digestive system distorts the body wall.

All animals can trace their lineage to a common ancestor that lived in the _____.

Neoproterozoic era

In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at exhibits protostome or deuterostome development?

The animal's coelom develops from the archenteron.

What do many organisms with deuterostome development have in common?

The blastopore formed during gastrulation becomes the anus.

Suppose a researcher for a pest-control company developed a chemical that inhibited the development of an embryonic mosquito's endodermal cells. Which of the following best explains the effectiveness of the pesticide?

The mosquito would have trouble digesting food, due to impaired gut function.

Which of the following is a feature of the digestive tube in most animal phyla?

The mouth and anus form the ends of the inner tube.

Select the correct statement about the evolution of animals.

The oldest generally accepted fossils of large animals range in age from 565 to 550 million years old.

Which of the following is radially symmetrical?

a doughnut

Soon after the coelom begins to form, a researcher injects a dye into the coelom of a deuterostome embryo. Into which of the following structures would you expect the dye to flow?

archenteron

Which of the following organisms was most likely the most recent common ancestor of all animals?

flagellated protist

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

flatworm

One of the characteristics unique to animals is

gastrulation.

Gastrulation is the process that directly forms the __________.

germ layers

Evidence of which structure or characteristic would be rare to find among fossils of the Ediacaran fauna?

hard parts

An important trend in animal evolution was cephalization, or development of a "head". An animal is said to show cephalization when it __________.

has an aggregation of sensory structures at one end of the body

Which of the following was an early selective advantage of a coelom in animals?

it contributed to a hydrostatic skeleton, allowing greater range of motion

If an organism exhibits a head with sensory structures, which of the following characteristics would it likely also exhibit?

it is bilaterally symmetrical

In the earthworm body plan, the digestive system can be described as a "tube-within-a-tube." Where would you expect to find most of the tissues that developed from endoderm?

lining the straw

Which of the following factors most likely contributed to the extinction of many Ediacaran life forms?

predation by new species, faster movement by new species, and increased developmental flexibility by new species

Which tissue type or organ is correctly matched with its germ layer tissue?

skin-ectoderm

While observing seawater through a microscope, you spot the embryo of an unknown animal. Which of the following criteria could you use to determine whether the organism exhibits protostome or deuterostome development?

spiral cleavage or radial cleavage

Which of the following statements is correct regarding animal body plans?

the body plans we see now have been evolutionarily advantageous compared to others in the past

Nine-banded armadillos give birth to four genetically identical offspring at a time. What does this fact suggest about the development of these organisms?

the embryo undergoes radial and indeterminate cleavage

Which of the following was probably an important factor in bringing about the Cambrian explosion?

the emergence of predator-prey relationships

Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?

the origin of Hox genes and the addition of new microRNAs

What is the primary difference between a coelom and a hemocoel?

their developmental origin

Each of the following statements describes characteristics of animals except for one. Which statement about animals is incorrect?

they have tissues, organs, and organ systems

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

tissues

Which of the following characteristics represents the oldest branch point in animal phylogeny?

true tissues or no tissues

Among organisms exhibiting protostome development, which morphological trait shows the most variation?

type of body cavity