Deck 31: Animal Origins and the Evolution of Body Plans

Question 1

The endosymbiotic dinoflagellates present in many corals

A) provide the corals with the products of photosynthesis.
B) allow corals to grow rapidly in clear, nutrient-poor tropical waters
C) can be lost when environmental conditions change.
D) All of the above
E) None of the above

Answer 1

D

Question 2

Clues to the evolutionary relationships of animals can be found in

A) the fossil record.
B) patterns of embryonic development.
C) comparative morphology and physiology.
D) nucleotide sequence patterns.
E) All of the above

Answer 2

E

Question 3

Which of the following is not one of the characteristics that distinguishes deuterostomes from protostomes?

A) Cleavage type
B) Ability to form a blastopore
C) Embryological origin of the mouth
D) Derivation of mesoderm
E) Position of the nervous system (dorsal/ventral)

Answer 3

B

Question 4

A bilaterally symmetrical animal can be divided into mirror images by

A) any plane through the midline of its body.
B) any plane from its anterior to its posterior end.
C) any plane from its dorsal to its ventral surface.
D) any plane through the midline of its body from its anterior to its posterior end.
E) a single plane through the midline of its body from its dorsal to its ventral surface.

Question 5

Because all animals must take in nutrients from their environment and digest their food internally, the nutritional mode of animals is called

A) heterotrophic.
B) photoheterotrophic.
C) photoautotrophic.
D) chemolithotrophic.
E) chemoautotrophic.

Question 6

Many parasites evolved complex life cycles because

A) they are too simple to disperse readily.
B) they are poor at recognizing new hosts.
C) they were driven to it by host defenses.
D) complex life cycles increase the probability of a parasite's transfer to a new host.
E) their ancestors had complex life cycles and they simply retained them.

Question 7

In the common ancestor of protostomes and deuterostomes, the pattern of early cleavage was

A) spiral.
B) radial.
C) biradial.
D) deterministic.
E) haphazard.

Question 8

A fluid-filled body cavity can function as a hydrostatic skeleton because

A) fluids are moderately compressible.
B) fluids are highly compressible.
C) fluids are incompressible at physiological pressures.
D) fluids have the same density as body tissues.
E) fluids can be moved by ciliary action.

Question 9

Bilateral symmetry

A) is found only among bilaterians.
B) is characteristic of all sponges.
C) is characteristic of all ctenophores.
D) is characteristic of all cnidarians.
E) None of the above

Question 10

Cephalization is most commonly associated with

A) spherical symmetry.
B) radial symmetry.
C) sessile animals.
D) bilateral symmetry.
E) lophophorate animals.

Question 11

Which of the following is not considered part of the body plan of an organism?

A) The symmetry of the body
B) The structure of the body cavity
C) The segmentation of the body
D) External appendages
E) The larval morphology

Question 12

The ancestor of the animal clade was probably a

A) colonial flagellated protist.
B) triploblastic acoelomate with spiral cleavage.
C) ciliated protist.
D) ctenophore.
E) None of the above

Question 13

Which of the following is a synapomorphy for the eumetazoans?

A) Distinct organ systems
B) Two embryonic cell layers
C) Radial symmetry
D) A blastopore that develops into the mouth
E) A blastopore that develops into the anus

Question 14

Among protostomes, cleavage of the fertilized egg is

A) delayed while the egg continues to mature.
B) always radial.
C) spiral, radial, or idiosyncratic.
D) triploblastic.
E) diploblastic.

Question 15

Which of the following features is a synapomorphy of the animals?

A) Cells that contain chitin
B) Vascular systems
C) Similarities in their Hox genes
D) Bilateral symmetry
E) Spiral cleavage

Question 16

The body plan of an animal is

A) its general structure.
B) the integrated functioning of its parts.
C) its general structure and the integrated functioning of its parts.
D) its general structure and its evolutionary history.
E) the integrated functioning of its parts and its evolutionary history.

Question 17

Spiral cleavage is found in which of the following taxa?

A) Lophotrocozoans, such as earthworms
B) Spirilians
C) Ecdysozoans, such as insects
D) Both a and b
E) Both b and c

Question 18

Which of the following is not a feature that enables some animals to capture large prey?

A) Sharp teeth
B) Claws
C) Toxins
D) A filtering device
E) Tentacles with stinging cells

Question 19

Bilaterally symmetrical animals can be divided into two major groups that separated during the Cambrian. These two lineages differ fundamentally in their

A) modes of reproduction.
B) early embryological development.
C) mode of obtaining and storing energy.
D) environmental requirements.
E) metabolism.

Question 20

The sponge body plan is characterized by

A) a mouth and digestive cavity but no muscles or nerves.
B) muscles and nerves but no mouth or digestive cavity.
C) a mouth, digestive cavity, and spicules.
D) muscles and spicules but no digestive cavity or nerves.
E) the lack of a mouth, digestive cavity, muscles, or nerves.

Question 21

Which of the following statements concerning nematocysts is true?

A) They are organelles used in the capture of prey by cnidarians.
B) They are excretory organs in platyhelminthes.
C) They are reproductive cells in cnidarians.
D) They are ciliated cells in sponges.
E) They are excretory cells in sponges.

Question 22

Which of the following structures is not involved with some mechanism of movement in animals?

A) Fluid-filled coelom
B) Segmentation
C) Appendages
D) Cilia
E) All of these structures are involved in movement.

Question 23

The divergence of the common ancestor of animals into the protostome and deuterostome lineages occurred during the

A) Cenozoic.
B) Silurian.
C) Jurassic.
D) Cambrian.
E) Mesozoic.

Question 24

Which of the following are not adaptations for predatory feeding?

A) Toxins
B) Camouflage
C) Sensitive sense organs
D) Long and complex digestive systems
E) All of the above are adaptations for predatory feeding.

Question 25

Most parasite species have a

A) simple life cycle and a single larval stage.
B) simple life cycle and a single host.
C) complex life cycle, multiple larval stages, and a single host.
D) complex life cycle, a single larval stage, and multiple hosts.
E) complex life cycle, multiple larval stages, and multiple hosts.

Question 26

The bilaterally symmetrical larval form found in many crustaceans is called a

A) trochophore.
B) nauplius.
C) planula.
D) caterpillar.
E) polyp.

Question 27

A pseudocolomate animal lacks a

A) body cavity.
B) fluid-filled body cavity.
C) fluid-filled body cavity lined on the outside with mesoderm.
D) fluid-filled body cavity lined on the outside and inside with mesoderm.
E) pseudocoel.

Question 28

Which of the following are not eumetazoans?

A) Ctenophores
B) Sponges
C) Cnidarians
D) Bilateria
E) Protostomes

Question 29

Segmentation of animals is important evolutionarily because it

A) allows organisms to grow much larger than would be possible without segmentation.
B) has allowed organisms to alter their body forms in complex ways.
C) increases the mobility of an organism.
D) reduces the surface area-to-volume ratio.
E) All of the above

Question 30

Which of the following is not associated with sponges?

A) Choanocytes
B) Pores
C) Spicules
D) Mesoderm
E) Eggs

Question 31

Which of the following stages is not part of the typical life cycle of a butterfly?

A) Trochophore
B) Egg
C) Pupa
D) Larva
E) Adult

Question 32

The body cavity of coelomate animals develops within the

A) endoderm.
B) ectoderm.
C) mesoderm.
D) pseudocoel.
E) mesoglea.

Question 33

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

A) A coelom is enclosed by muscles on the outside only; a pseudocoelom is enclosed by muscles on the inside only.
B) A coelom does not have an enclosed body cavity; a pseudocoelom is completely surrounded by muscle.
C) A coelom is enclosed by muscles on the inside only; a pseudocoelom is a solid structure.
D) A coelom is enclosed by muscles on the inside and the outside; a pseudocoelom is surrounded by muscle on the outside of the body cavity.
E) None of the above

Question 34

Motile filter feeders include

A) flamingos
B) blue whales
C) polychaetes
D) Both a and b
E) All of the above

Question 35

Which sponge cell type is specialized for creating the currents that draw food particles into the sponge?

A) Spicule
B) Pore cell
C) Osculum
D) Choanocyte
E) Nematocyst

Question 36

The man-of-war is an example of a deadly

A) sponge.
B) cnidarian.
C) ctenophore.
D) nematocyst.
E) mollusk.

Question 37

The terms "acoelomate," "pseudocoelomate," and "coelomate" refer to

A) levels of cephalization.
B) the origin of the blastopore.
C) ectoderm, mesoderm, and endoderm.
D) the body cavity of animals.
E) the vertebrate body plan.

Question 38

Which of the following variables may be part of an evolutionary trade-off that confronts animal species?

A) Long egg incubation period
B) Ability to filter small food particles out of water
C) Production of many small eggs
D) Production of altricial young
E) All of the above

Question 39

Cnidarians have the type of symmetry known as _______ symmetry.

A) asymmetrical
B) radial
C) spherical
D) bilateral
E) axial

Question 40

Which of the following feeding strategies is most likely to be associated with a sessile organism?

A) Filter feeding
B) Herbivory
C) Predation
D) Parasitism
E) Detritus feeding

Question 41

Which of the following is not a characteristic of the sponge body plan?

A) Gastrovascular cavity
B) No distinct tissue layers or organs
C) No separation between the different cell layers
D) Organization around a water canal system
E) Asymmetry

Question 42

The simplest type of symmetry, in which body parts radiate outward from a central point, is called _______ symmetry. It is widespread among the protists.

Question 43

Animals most likely arose from colonial flagellated protists as a result of division of labor among their aggregated cells. Among the extant animals, the _______ bear the strongest similarity to the most recent common ancestor of animals.

Question 44

Which of the following groups consists of members that are entirely colonial and sessile?

A) Sea anemones
B) Hydrozoans
C) Jellyfishes
D) Corals
E) Nematocysts

Question 45

_______ symmetry is strongly correlated with cephalization: the development of sense organs and central nervous tissues at the anterior end of an animal.

Question 46

Placozoans, ctenophorans, and cnidarians are all considered _______, since they have inner and outer cell layers.

Question 47

Which of the following is a significant threat to the coral reefs in many parts of the world?

A) Global warming
B) Boat traffic
C) Air pollution
D) Hurricane damage
E) Oil spills

Question 48

Which of the following characteristics is not associated with the cnidarians?

A) Alternation between polyp and medusa
B) Three distinct body layers
C) Nematocysts
D) Gastrovascular cavity
E) Planula larva

Question 49

Which cnidarian group is geologically important because growth of its members can result in the formation of islands and atolls?

A) Hydrozoans
B) Scyphozoans
C) Anthozoans
D) Turbellarians
E) Ctenophores

Question 50

The existence of three embryonic cell layers, including an outer _______, an inner _______, and a middle _______, is a synapomorphy for protostomes and deuterostomes.

Question 51

The type of symmetry possessed by cnidaria, which have a cylindrical form with one main axis around which body parts are arranged, is called _______ symmetry.

Question 52

Which of the following traits is not shared by all animals?

A) Specific types of cell-cell junctions
B) A common set of extracellular matrix molecules
C) A complete gut
D) Similarities in their small-subunit ribosomal RNAs
E) Similarities in their Hox genes

Question 53

Of the more than 9,000 species of sponges, _______ live in fresh water.

A) 20
B) 50
C) 1,000
D) 4,500
E) 8,000

Question 54

The embryos of _______ animals have two cell layers: an outer _______ and an inner _______.

Question 55

Among the _______, the mouth arises from the blastopore, an embryonic feature that is a synapomorphy of the group.

Question 56

The placozoans are considered to be the sister group to which of the following taxa?

A) Ctenophorans
B) Cnidarians
C) Bilaterians
D) Sponges
E) Eumetazoa

Question 57

Which of the following statements about anthozoans is true?

A) They reproduce asexually only.
B) They are commonly known as jellyfish.
C) There are both solitary and colonial species.
D) Their gametes are produced directly by the medusa.
E) Nematocysts are not common in this group.

Question 58

Which of the following taxa has the largest number of described species?

A) Sponges
B) Placozoans
C) Ctenophorans
D) Cnidarians
E) Phoronids

Question 59

Sponges differ from other animals in that they

A) do not form true organs.
B) are sessile.
C) are triploblastic.
D) have trochophore larvae.
E) Both a and b

Question 60

Corals are able to survive in nutrient-poor tropical waters by forming symbiotic relationships with photosynthetic

A) plants.
B) red algae.
C) brown algae.
D) dinoflagellates.
E) None of the above

Question 61

The fluid-filled body cavities of animals function as _______ skeletons.

Question 62

Use the following to answer questions :
Refer to the diagram below, showing an animal cross-section.
Is this animal acoelomate, pseudocoelomate, or coelomate?

Question 63

Use the following to answer questions :
Refer to the diagram below, depicting a sponge cross-section.
Which structure is a choanocyte?

Question 64

The _______ are marine cnidarians with a thick, firm mesoglea within the medusa.

Question 65

Animals that lack an enclosed body cavity, such as flatworms, are called _______.

Question 66

_______ are organisms that eat both plants and animals.

Question 67

Use the following to answer questions :
Refer to the diagram below, depicting a sponge cross-section.

-Which structure is a spicule?

Question 68

Use the following to answer questions :
Refer to the diagram below, showing the life cycle of a cnidarian.
Which letter points to the polyp stage? Is it solitary or colonial?

Question 69

Derived cnidarian classes have life cycles involving two stages: the _______ and the _______.

Question 70

Use the following to answer questions :
Refer to the diagram below, showing an animal cross-section.
Identify the labeled structures.

Question 71

The organisms that make up the sister group of all bilaterally symmetrical animals (protostomes and deuterostomes) are the _______ and _______.

Question 72

Use the following to answer questions :
Refer to the diagram below, depicting a sponge cross-section.
Which structure is an opening for water to enter the sponge?

Question 73

Animals that live in or on another organism and obtain nutrients from it are known as _______.

Question 74

Organisms that feed on decomposing organic matter are known as _______.

Question 75

Use the following to answer questions :
Refer to the diagram below, showing the life cycle of a cnidarian.
Of the three main clades of cnidarians, which class is shown?

Question 76

There are three major groups of cnidarians: the _______ (which include sessile colonial corals), the _______ (commonly known as jellyfish), and the _______.

Question 77

The immature life stage of some organisms before they assume their adult form is called the _______.

Question 78

Use the following to answer questions :
Refer to the diagram below, depicting a sponge cross-section.
Which structure is an epidermal cell?

Question 79

Ctenophores can be distinguished from the cnidarians by their possession of a _______ and comblike plates known as ctenes.

Question 80

The _______ is a free-swimming ciliated larva found in the radially symmetrical metazoans.