Question 1

What do all deuterostomes have in common?

Accepted Answer

Deuterostomes are characterized by the fact that during embryonic development, the pore formed during gastrulation becomes the anus. This is a key feature that distinguishes them from protostomes, where the pore becomes the mouth.

Question 2

How are hemichordates,urochordates,and cephalochordates similar?

Accepted Answer

Hemichordates, urochordates, and cephalochordates are all part of the chordate phylum and have pharyngeal gill slits at some point during their development. This is a defining characteristic of the chordates. However, they differ in other ways. Hemichordates have a tripartite body plan with a proboscis, collar, and trunk region. Urochordates are more closely related to vertebrates and have a tunic-like covering and a filtering apparatus to draw in food. Cephalochordates have a segmented body and retain their notochord throughout their life.

Question 3

Which of the following adult animals might you find floating in the open ocean,suspension feeding using its pharyngeal gill slits?

Accepted Answer

Salps are gelatinous, barrel-shaped animals that float in the open ocean and feed on phytoplankton by filtering water through their pharyngeal gill slits. The other choices either do not float in the open ocean or do not have pharyngeal gill slits.

Question 4

Suppose you traveled back in time and located the first animals to have developed feathers.You found that these animals were tree-dwelling ectotherms,able to run quickly but unable to fly.You also noticed that females of the species had no feathers at all,while males had bright blue feathers covering their tails.Which hypothesis of feather evolution would these data most support?

Accepted Answer

The fact that only males have brightly colored feathers on their tails suggests that they are being used for courtship displays rather than flight or insulation. The tree-dwelling ectotherm lifestyle also does not support the idea of feathers evolving for flight or gliding.

Question 5

What would be the result(s)if a tunicate's pharyngeal gill slits were suddenly blocked?

Accepted Answer

Tunicates rely on their pharyngeal gill slits for both respiration and feeding, so blocking them would result in difficulties with both functions. However, tunicates do not use their gill slits for movement, so choice C and E are incorrect. Choice A is incorrect because it implies that the organism would only have difficulty with respiration, which is not comprehensive enough to cover the potential impact of blocked gill slits.

Question 6

When bone first evolved in vertebrates,what structure did it form?

Accepted Answer

Bone first evolved in vertebrates as part of an exoskeleton, providing external protection and support.

Question 7

As you are walking along a beach,you find an animal and believe that it belongs to the class Asteroidea.Which of the following characteristics would support your hypothesis that the animal is a sea star and not another type of echinoderm?

Accepted Answer

Sea stars, or Asteroidea, typically have a central disc that is not well-delineated from their arms, which distinguishes them from other echinoderms like brittle stars.

Question 8

Which of the following classes is comprised of carnivorous predators that are able to extend their stomachs through their mouths to feed?

Accepted Answer

Asteroidea, or sea stars, are carnivorous predators that are able to extend their stomachs through their mouths to feed on prey such as clams and mussels. Ophiuroidea, Holothuroidea, Crinoidea, and Echinoidea are not known for this feeding behavior.

Question 9

Which of the following have distinct central disks and long,flexible arms?

Accepted Answer

Class Ophiuroidea, also known as brittle stars, have distinct central disks and long, flexible arms. The other classes listed either have no distinct central disk or do not have long, flexible arms.

Question 10

If you found a fossil fish and had dated it to 400 mya,what feature might indicate that it is actually younger than you first thought?

Accepted Answer

The presence of four limbs would indicate that the fossil is younger than 400 million years ago, as tetrapods (four-limbed vertebrates) evolved after this period.

Question 11

What would you expect to happen if the midbrain of a fish became damaged?

Accepted Answer

The midbrain of a fish plays a crucial role in processing visual information, so if it became damaged, the fish's vision would likely be impaired.

Question 12

Why do adult urochordates (tunicates)lack notochords,even though larval urochordates have them?

Accepted Answer

The notochord is primarily used for locomotion, particularly in swimming. As adult urochordates are sessile and do not move actively, they do not need a notochord for locomotion. Therefore, they have lost the notochord during their development into adults.

Question 13

The discovery of Caudipteryx is significant in evolutionary biology because it strengthened which one of the following hypotheses?

Accepted Answer

The discovery of Caudipteryx, a feathered dinosaur with bird-like characteristics, provided evidence for the evolutionary link between dinosaurs and birds, therefore strengthening the hypothesis that birds evolved from a dinosaur ancestor.

Question 14

You believe that an adult animal you are examining is a vertebrate but concede that it may be an invertebrate chordate.Which of the following would ensure that you are indeed looking at a vertebrate?

Accepted Answer

Vertebrates are characterized by having a vertebral column, which replaces the notochord found in embryonic stages and some adult invertebrates. If an animal lacks a notochord, it indicates the presence of a vertebral column, thus confirming it is a vertebrate.

Question 15

The structure that develops into the vertebrate spinal cord is the _____.

Accepted Answer

The dorsal hollow nerve cord is a key structure in the development of the vertebrate nervous system. In early embryonic development, this structure folds in on itself and becomes the neural tube, which later goes on to form the brain and spinal cord. Therefore, the structure that develops into the vertebrate spinal cord is the dorsal hollow nerve cord.

Question 16

How did the development of the jaw contribute to evolutionary diversification of early vertebrate lineages?

Accepted Answer

The development of the jaw allowed early vertebrates to exploit a wider range of food sources, leading to increased dietary diversity and ecological opportunities, which contributed to evolutionary diversification.

Question 17

If a kelp farmer wanted to maximize her harvest,which type of echinoderm would she be most concerned about in the habitat?

Accepted Answer

Sea urchins are known to be herbivores and feed on kelp, which can drastically reduce the kelp harvest. Therefore, a kelp farmer would be most concerned about sea urchins in the habitat if they wanted to maximize their kelp harvest.

Question 18

The fishes form a(n)_____,a sequence of paraphyletic lineages.

Accepted Answer

The term "fishes" is not a monophyletic group as it includes multiple lineages that are not closely related to each other. Therefore, the correct term to describe them would be "grade," which refers to a sequence of paraphyletic lineages that share a similar trait or characteristic.

Question 19

Which of the following is a characteristic of all chordates at some point during their life cycle?

Accepted Answer

A tail is a characteristic of all chordates at some point during their life cycle. Even humans have a tail during their embryonic development, although it usually disappears before birth.

Question 20

What is the best evidence currently available that tetrapod limbs evolved from fish fins?

Accepted Answer

Molecular genetic evidence reveals regulatory enzymes that are homologous in fish and tetrapods, indicating a common ancestry and supporting the evolution of tetrapod limbs from fish fins. The other choices provide some evidence but are not as strong in supporting the evolutionary link.

Quiz 34: Deuterostome Animals