Deck 27: The Rise of Animal Diversity

Question 1

The members of which clade in the phylum Cnidaria occur only as polyps?

A) Hydrozoa
B) Scyphozoa
C) Anthozoa
D) Cubozoa

Answer 1

C

Question 2

Corals are most closely related to which group?

A) jellies
B) freshwater hydras
C) sea anemones
D) sponges
E) barnacles

Answer 2

C

Question 3

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

A) preying on animals.
B) ingesting it.
C) consuming living, rather than dead, prey.
D) using enzymes to digest their food.

Answer 3

B

Question 4

The most ancient branch point in animal phylogeny is that between having

A) radial or bilateral symmetry.
B) a well-defined head or no head.
C) diploblastic or triploblastic embryos.
D) true tissues or no tissues.
E) a body cavity or no body cavity.

Question 5

Which of the following characterize at least some members of the phylum Cnidaria? 1. a gastrovascular cavity
2) a polyp stage
3) a medusa stage
4) cnidocytes
5) a pseudocoelom

A) 1
B) 2 and 3
C) 3, 4, and 5
D) 1, 2, 3, and 4
E) All of the above are correct

Question 6

Which of the following is a diploblastic phylum of aquatic predators?

A) Cnidaria
B) Annelida
C) Mollusca
D) Arthropoda
E) Echinodermata

Question 7

Which of the following is (are) unique to animals?

A) cells that have mitochondria
B) the structural carbohydrate, chitin
C) nervous conduction and muscular movement
D) heterotrophy
E) flagellated gametes

Question 8

The last common ancestor of all animals was probably a

A) unicellular chytrid.
B) unicellular yeast.
C) multicellular algae.
D) multicellular fungus.
E) flagellated protist.

Question 9

Some researchers claim that sponge genomes have homeotic genes, but no Hox genes. If true, this finding would

A) strengthen sponges' evolutionary ties to the Eumetazoa.
B) mean that sponges must no longer be classified as animals.
C) confirm the identity of sponges as "basal animals."
D) mean that extinct sponges must have been the last common ancestor of animals and fungi.
E) require sponges to be reclassified as choanoflagellates.

Question 10

Sponges are most accurately described as

A) marine predators.
B) chemoautrophs.
C) freshwater scavengers.
D) filter feeders.
E) aquatic predators.

Question 11

If the current molecular evidence regarding animal origins is well substantiated in the future, then what will be true of any contrary evidence regarding the origin of animals derived from the fossil record?

A) The contrary fossil evidence will be seen as a hoax.
B) The fossil evidence will be understood to have been interpreted incorrectly because it is incomplete.
C) The fossil record will henceforth be ignored.
D) Phylogenies involving even the smallest bit of fossil evidence will need to be discarded.
E) Only phylogenies based solely on fossil evidence will need to be discarded.

Question 12

According to the evidence collected so far, the animal kingdom is

A) monophyletic.
B) paraphyletic.
C) polyphyletic.
D) euphyletic.
E) multiphyletic.

Question 13

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

A) true tissues
B) hard parts
C) bilateral symmetry
D) cephalization
E) embryos

Question 14

If a multicellular animal lacks true tissues, then it can properly be included among the

A) eumetazoans.
B) metazoans.
C) choanoflagellates.
D) lophotrochozoans.
E) bilateria.

Question 15

Which of the following is true of members of the phylum Cnidaria?

A) They are not capable of locomotion because they lack true muscle tissue.
B) They are primarily filter feeders.
C) They have either, or both, of two body forms: mobile polyps and sessile medusae.
D) They may use a gastrovascular cavity as a hydrostatic skeleton.
E) They are the simplest organisms with a complete alimentary canal (two openings).

Question 16

A sponge's structural materials (spicules, spongin) are manufactured by the

A) pore cells.
B) epidermal cells.
C) choanocytes.
D) amoebocytes.

Question 17

Which of the following statements concerning animal taxonomy is (are) true? 1. Animals are more closely related to plants than to fungi.
2) All animal clades based on body plan have been found to be incorrect.
3) Kingdom Animalia is monophyletic.
4) Only animals reproduce by sexual means.
5) Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.

A) 5 only
B) 1 and 3
C) 3 and 5
D) 3, 4, and 5

Question 18

Which clade in the phylum Cnidaria includes "jellies" with rounded (as opposed to boxlike) medusae?

A) Hydrozoa
B) Scyphozoa
C) Anthozoa
D) Cubozoa

Question 19

In terms of food capture, which sponge cell is most similar to the cnidocyte of a cnidarian?

A) amoebocyte
B) choanocyte
C) epidermal cell
D) pore cell

Question 20

Which characteristic(s) is (are) shared by both cnidarians and flatworms?

A) dorsoventrally flattened bodies
B) true muscle
C) radial symmetry
D) a digestive system with a single opening
E) two of these

Question 21

How many of the following statements about craniates is (are) correct? 1. Craniates are more highly cephalized than are noncraniate chordates.
2) Craniates' genomic evolution includes duplication of clusters of genes that code for transcription factors.
3) The craniate clade is synonymous with the vertebrate clade.
4) Pharyngeal slits that play a major role in gas exchange originated in craniates.
5) The two-chambered heart originated with the early craniates.

A) only 1 is correct
B) 1 and 5 are correct
C) 2, 3, and 5 are correct
D) 1, 2, 4, and 5 are correct
E) all 5 options are correct

Question 22

A new species of aquatic chordate is discovered that closely resembles an ancient form. It has the following characteristics: external armor of bony plates, no paired lateral fins, and a suspension-feeding mode of nutrition. In addition to these, it will probably have which of the following characteristics?

A) legs
B) no jaws
C) an amniotic egg
D) endothermy

Question 23

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of

A) mass extinction.
B) evolutionary stasis.
C) adaptive radiation.
D) a large meteor impact.

Question 24

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

A) binary fission
B) mitosis
C) random segregation
D) gene duplication
E) chromosomal condensation

Question 25

Which extant chordates are postulated to be most like the earliest chordates in appearance?

A) lancelets
B) adult tunicates
C) amphibians
D) reptiles
E) chondrichthyans

Question 26

Which of these, if true, would support the claim that the ancestral cnidarians had bilateral symmetry? 1. Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects.
2) Cnidarians have fewer Hox genes than bilaterians.
3) All extant cnidarians, including Nematostella, are diploblastic.
4) β-catenin turns out to be essential for gastrulation in all animals in which it occurs.
5) All cnidarians are acoelomate.

A) 1 only
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 4 and 5

Question 27

At least one of these has been found in all species of eumetazoan animals studied thus far.

A) Hox
B) Dlx
C) Otx
D) FOXP2
E) more than one of these

Question 28

Which statement is most consistent with the hypothesis that the Cambrian explosion was caused by the rise of predator-prey relationships?

A) increased incidence of worm burrows in the fossil record
B) increased incidence of larger animals in the fossil record
C) increased incidence of organic material in the fossil record
D) increased incidence of fern galls in the fossil record
E) increased incidence of hard parts in the fossil record

Question 29

Chordate pharyngeal slits appear to have functioned first as

A) the digestive system's opening.
B) suspension-feeding devices.
C) components of the jaw.
D) gill slits for respiration.
E) portions of the inner ear.

Question 30

What is the probable sequence in which the following clades of animals originated, from earliest to most recent? 1. tetrapods
2) vertebrates
3) deuterostomes
4) amniotes
5) bilaterians

A) 5 → 3 → 2 → 4 → 1
B) 5 → 3 → 2 → 1 → 4
C) 5 → 3 → 4 → 2 → 1
D) 3 → 5 → 4 → 2 → 1
E) 3 → 5 → 2 → 1 → 4

Question 31

Which of the following animal groups is entirely aquatic?

A) Mollusca
B) Crustacea
C) Echinodermata
D) Nematoda
E) Platyhelminthes

Question 32

The Hox genes came to regulate each of the following in what sequence, from earliest to most recent? 1. identity and position of paired appendages in protostome embryos
2) anterior-posterior orientation of segments in protostome embryos
3) positioning of tentacles in cnidarians
4) anterior-posterior orientation in vertebrate embryos

A) 4 → 1 → 3 → 2
B) 4 → 2 → 3 → 1
C) 4 → 2 → 1 → 3
D) 3 → 2 → 1 → 4
E) 3 → 4 → 1 → 2

Question 33

A brachiopod can be distinguished from a bivalve by the presence of

A) two hinged shells.
B) a digestive system with separate mouth and anus.
C) a lophophore.
D) suspension feeding.
E) a distinct head.

Question 34

An adult animal that possesses bilateral symmetry is most certainly also

A) triploblastic.
B) a deuterostome.
C) eucoelomate.
D) highly cephalized.

Question 35

If nudibranch rhinophores are located at the anteriors of these sea slugs, then they contribute to the sea slugs'

A) segmentation.
B) lack of torsion.
C) cephalization.
D) identity as lophotrochozoans.
E) ability to successfully carry out a sessile lifestyle.

Question 36

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

A) Radiata should be a true clade.
B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait.
C) Hox genes play little actual role in coding for an animal's "body plan."
D) Cnidaria may someday replace porifera as the basal bilaterians.
E) cnidarians are the basal metazoans.

Question 37

Fossil evidence indicates that the following events occurred in what sequence, from earliest to most recent? 1. Protostomes invade terrestrial environments.
2) Cambrian explosion occurs.
3) Deuterostomes invade terrestrial environments.
4) Vertebrates become top predators in the seas.

A) 2 → 4 → 3 → 1
B) 2 → 1 → 4 → 3
C) 2 → 4 → 1 → 3
D) 2 → 3 → 1 → 4
E) 2 → 1 → 3 → 4

Question 38

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

A) body cavity between body wall and digestive system
B) number of embryonic tissue layers
C) type of body symmetry
D) presence of Hox genes
E) degree of cephalization

Question 39

What do all craniates have that earlier chordates did not have?

A) brain
B) vertebrae
C) cartilaginous pipe surrounding notochord
D) partial or complete skull
E) bone

Question 40

Which of the following statements would be least acceptable to most zoologists?

A) The extant lancelets are contemporaries, not ancestors, of vertebrates.
B) The first fossils resembling lancelets appeared in the fossil record around 530 million years ago.
C) Recent work in molecular systematics supports the hypothesis that lancelets are the basal clade of chordates.
D) The extant lancelets are the immediate ancestors of the fishes.
E) Lancelets display the same method of swimming as do fishes.

Question 41

Which of the following are the only extant animals that descended directly from dinosaurs?

A) lizards
B) crocodiles
C) snakes
D) birds
E) tuataras

Question 42

Which of the following belong to the lobe-fin clade?

A) chondrichthyans
B) ray-finned fishes
C) lampreys
D) hagfishes
E) tetrapods

Question 43

During chordate evolution, what is the sequence (from earliest to most recent) in which the following structures arose? 1. amniotic egg
2) paired fins
3) jaws
4) swim bladder
5) four-chambered heart

A) 2, 3, 4, 1, 5
B) 3, 2, 4, 1, 5
C) 3, 2, 1, 4, 5
D) 2, 1, 4, 3, 5
E) 2, 4, 3, 1, 5

Question 44

To which of the following are the scales of chondrichthyans most closely related in a structural sense?

A) osteichthyan scales
B) reptilian scales
C) mammalian scales
D) bird scales
E) chondrichthyan teeth

Question 45

What should be true of fossils of the earliest tetrapods?

A) They should show evidence of internal fertilization.
B) They should show evidence of having produced shelled eggs.
C) They should indicate limited adaptation to life on land.
D) They should be transitional forms with the fossils of chondrichthyans that lived at the same time.
E) They should feature the earliest indications of the appearance of jaws.

Question 46

A team of researchers has developed a poison that has proven effective against lamprey larvae in freshwater cultures. The poison is ingested and causes paralysis by detaching segmental muscles from the skeletal elements. The team wants to test the poison's effectiveness in streams feeding Lake Michigan, but one critic worries about potential effects on lancelets, which are similar to lampreys in many ways. Why is this concern misplaced?

A) A chemical poisonous to lampreys could not also be toxic to organisms as ancestral as lancelets.
B) Lamprey larvae and lancelets have very different feeding mechanisms.
C) Lancelets do not have segmental muscles.
D) Lancelets live only in saltwater environments.
E) Lancelets and lamprey larvae eat different kinds of food.

Question 47

There is evidence that ray-finned fishes evolved

A) in response to a crisis that wiped out the chondrichthyans.
B) directly from lampreys and hagfish.
C) early in the Cambrian period.
D) directly from lancelets.
E) the swim bladder from a lung.

Question 48

Which of these might have been observed in the common ancestor of chondrichthyans and osteichthyans?

A) a mineralized, bony skeleton
B) opercula
C) bony fin rays
D) a spiral valve intestine
E) a swim bladder

Question 49

The swim bladder of ray-finned fishes

A) was probably modified from simple lungs of chondrichthyans.
B) developed into lungs in saltwater fishes.
C) first appeared in sharks.
D) provides for regulation of buoyancy.
E) Two of the options listed are correct.

Question 50

Which of the following are the most abundant and diverse of the extant vertebrates?

A) ray-finned fishes
B) birds
C) amphibians
D) nonbird reptiles
E) mammals

Question 51

The feeding mode of the extinct conodonts was

A) herbivory.
B) suspension feeding.
C) predation.
D) filter feeding.
E) absorptive feeding.

Question 52

A trend first observed in the evolution of the earliest tetrapods was

A) the appearance of jaws.
B) the appearance of bony vertebrae.
C) feet with digits.
D) the mineralization of the endoskeleton.
E) the amniotic egg.

Question 53

The earliest known mineralized structures in vertebrates are associated with which function?

A) reproduction
B) feeding
C) locomotion
D) defense
E) respiration

Question 54

Which group's members have had both lungs and gills during their adult lives?

A) sharks, skates, and rays
B) lungfishes
C) lancelets
D) amphibians
E) ichthyosaurs and plesiosaurs

Question 55

Jaws first occurred in which extant group of fishes?

A) lampreys
B) chondrichthyans
C) ray-finned fishes
D) lungfishes
E) placoderms

Question 56

Which of these are amniotes?

A) amphibians
B) fishes
C) mammals
D) placental mammals only
E) egg-laying mammals only

Question 57

Lampreys differ from hagfishes in

A) lacking jaws.
B) having a cranium.
C) having pharyngeal clefts that develop into pharyngeal slits.
D) having a notochord throughout life.
E) having a notochord that is surrounded by a tube of cartilage.

Question 58

Which of these characteristics added most to vertebrate success in relatively dry environments?

A) the shelled, amniotic egg
B) the ability to maintain a constant body temperature
C) two pairs of appendages
D) bony scales
E) a four-chambered heart

Question 59

Why is the amniotic egg considered an important evolutionary breakthrough?

A) It has a shell that increases gas exchange.
B) It allows deposition of eggs in a terrestrial environment.
C) It prolongs embryonic development.
D) It provides insulation to conserve heat.
E) It permits internal fertilization to be replaced by external fertilization.

Question 60

Arrange these taxonomic terms from most inclusive (most general) to least inclusive (most specific). 1. lobe-fins
2) amphibians
3) gnathostomes
4) osteichthyans
5) tetrapods

A) 4, 3, 1, 5, 2
B) 4, 3, 2, 5, 1
C) 4, 2, 3, 5, 1
D) 3, 4, 1, 5, 2
E) 3, 4, 5, 1, 2

Question 61

As a result of harvesting a higher proportion of older and larger cod and other fish species for food

A) the number of fish in these populations has increased dramatically.
B) the age and size of fish reaching sexual maturity have decreased.
C) many new species of predators have evolved in these regions.
D) the affected fish species have stopped reproducing.
E) many of the fish in these populations have started to reproduce asexually.

Question 62

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, although the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. The next three questions refer to the phylogenetic trees that follow.
I.
II.
III.

Which phylogeny has been created by emphasizing the structural simplicity of placozoans?

A) I
B) II
C) III

Question 63

The decline of cyanobacteria in the early Cambrian oceans was most likely related to

A) the movement of animals onto land.
B) the evolution of land plants.
C) an increase in the number of predatory fish.
D) an increase in filter-feeding organisms.
E) a decline in the number of marine decomposers.

Question 64

In the traditional phylogeny (A), the phylum Platyhelminthes is depicted as a sister taxon to the rest of the protostome phyla, and as having diverged earlier from the lineage that led to the rest of the protostomes. In the molecular phylogeny (B), Platyhelminthes is depicted as a lophotrochozoan phylum. What probably led to this change?

A) Platyhelminthes ceased to be recognized as true protostomes.
B) The removal of the acoel flatworms (Acoela) from the Platyhelminthes allowed the remaining flatworms to be clearly tied to the Lophotrochozoa.
C) All Platyhelminthes must have a well-developed lophophore as their feeding apparatus.
D) Platyhelminthes' close genetic ties to the arthropods became clear as their Hox gene sequences were studied.

Question 65

What is true of the deuterostomes in the molecular phylogeny (B) that is not true in the traditional phylogeny (A)?

A) Deuterostomia is paraphyletic.
B) To maintain Deuterostomia as a clade, some phyla had to be removed from it.
C) Deuterostomia now includes the Acoela.
D) It is actually a grade, rather than a clade.
E) It diverged from the rest of the Bilateria earlier than did the Acoela.

Question 66

Organisms at which of the following trophic levels increased the most because of the movement of animals onto land?

A) herbivores and carnivores
B) decomposers and producers
C) producers
D) decomposers

Question 67

Arthropods invaded land about 100 million years before vertebrates did so. This most clearly implies that

A) arthropods evolved before vertebrates did.
B) extant terrestrial arthropods are better adapted to terrestrial life than are extant terrestrial vertebrates.
C) ancestral arthropods must have been poorly adapted to aquatic life, and thus experienced a selective pressure to invade land.
D) vertebrates evolved from arthropods.
E) arthropods have had more time to coevolve with land plants than have vertebrates.

Question 68

If all of the animals died in a large region of an ocean, we would expect an increase in the

A) number of filter feeders.
B) number of cyanobacteria.
C) number of decomposers.
D) clarity of the ocean waters.
E) temperature of the ocean waters.

Question 69

Figure 27.1
Which of the following factors, when used to label the horizontal axis of the graph in Figure 27.1, would account most directly for the shape of the plot?

A) spongin concentration (gm/unit volume)
B) rate of cribrostatin synthesis (molecules/unit time)
C) number of pores per sponge
D) number of spicules per sponge
E) number of choanocytes per sponge

Question 70

A: Morphological phylogeny.
B: Molecular phylogeny.
Which of the following is a point of conflict between the phylogenetic analyses presented in these two figures?

A) the relationship of taxa of segmented animals to taxa of nonsegmented animals
B) that sponges are basal animals
C) that chordates are deuterostomes
D) the monophyly of the bilaterians
E) the monophyly of the animal kingdom

Question 71

A new, sixth global mass-extinction event appears to be occurring on Earth today. The most likely explanation for the dramatic loss of species is

A) global warming.
B) natural fluctuations in global temperatures and precipitation.
C) the evolution of new types of viruses.
D) human activity that alters natural environments.
E) decreases in atmospheric levels of oxygen.

Question 72

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, although the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. The next three questions refer to the phylogenetic trees that follow.
I.
II.
III.

Which phylogeny has been created by emphasizing genomic features of placozoans?

A) I
B) II
C) III

Question 73

Evidence indicates that an ancestral finch species from South America arrived on the Galapágos Islands and formed many new species, adapting to the diverse environments on the islands. With the evolution of these new bird species on the Galapágos Islands, we expect to find a corresponding

A) increase in the number of bird parasites on the Galapágos Islands.
B) decrease in the number of bird parasites on the Galapágos Islands.
C) increase in the number of bird parasites in South America.
D) decrease in the number of bird parasites in South America.
E) elimination of bird parasites on the Galapágos Islands.

Question 74

Among the invertebrate phyla, phylum Arthropoda is unique in possessing members that have

A) a cuticle.
B) a ventral nerve cord.
C) open circulation.
D) wings.
E) segmented bodies.

Question 75

Figure 27.2
Fishes that have swim bladders can regulate their density and thus their buoyancy. There are two types of swim bladder: physostomus and physoclistus. The ancestral version is the physostomus version, in which the swim bladder is connected to the esophagus via a short tube (Figure 27.2). The fish fills this version by swimming to the surface, taking gulps of air, and directing them into the swim bladder. Air is removed from this version by "belching." The physoclistus version is more derived, and has lost its connection to the esophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder.
The presence of a swim bladder allows the typical ray-finned fish to stop swimming and still

A) effectively circulate its blood.
B) be highly maneuverable.
C) use its lateral line system.
D) use its swim bladder as a respiratory organ.
E) not sink.

Question 76

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, although the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. The next three questions refer to the phylogenetic trees that follow.
I.
II.
III.

Which phylogeny has been created by emphasizing a protein found in placozoans?

A) I
B) II
C) III

Question 77

Match the extant vertebrate group with the description. Internal fertilization, leathery amniotic egg, and skin that resists drying are characteristics of

A) amphibians.
B) nonbird reptiles.
C) chondrichthyans.
D) mammals.
E) birds.

Question 78

Figure 27.2
Fishes that have swim bladders can regulate their density and thus their buoyancy. There are two types of swim bladder: physostomus and physoclistus. The ancestral version is the physostomus version, in which the swim bladder is connected to the esophagus via a short tube (Figure 27.2). The fish fills this version by swimming to the surface, taking gulps of air, and directing them into the swim bladder. Air is removed from this version by "belching." The physoclistus version is more derived, and has lost its connection to the esophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder.
Rank the following fish, from most to least, in terms of the amount of energy each must use to maintain its position (depth) in the water column over the long term. 1. physoclistus fish
2) physostomus fish
3) chondrichthyan fish

A) 1, 2, 3
B) 2, 3, 1
C) 2, 1, 3
D) 3, 1, 2
E) 3, 2, 1

Question 79

Which of these would a paleontologist be most likely to do in order to determine whether a fossil represents a reptile or a mammal?

A) Look for the presence of milk-producing glands.
B) Look for the mammalian characteristics of a four-chambered heart and a diaphragm.
C) Because mammals are eutherians, look for evidence of a placenta.
D) Use molecular analysis to look for the protein keratin.
E) Examine the teeth.

Question 80

In which vertebrates is fertilization exclusively internal?

A) chondrichthyans, osteichthyans, and mammals
B) amphibians, mammals, and reptiles
C) chondrichthyans, osteichthyans, and reptiles
D) reptiles and mammals
E) reptiles and amphibians