Question 1

You are examining a new animal species.You find that you can pass a line through any longitudinal plane and find equal halves.Evaluate the symmetry of this animal.
A)spherical
B)radial
C)bilateral

Accepted Answer

Radial symmetry is characterized by the ability to divide an organism into roughly equal halves through any longitudinal plane, which matches the description provided.

Question 2

What does the mesoderm have to do with the designation of a true coelom?
A)The mesoderm gives rise to the fluid found within the coelom.
B)The mesoderm gives rise to the lining of the coelom.
C)The mesoderm gives rise to the outer covering of the coelom.
D)The mesoderm gives rise to the structure of the coelom wall.
E)The mesoderm has nothing to do with the coelom.

Accepted Answer

The mesoderm gives rise to the lining of the coelom, which is a fluid-filled body cavity completely surrounded by mesoderm-derived tissue. This is why the presence of a true coelom (as opposed to a pseudocoelom or no coelom) is closely linked to the development of mesoderm during embryonic development.

Question 3

If it were found that all animals except the Parazoa had a particular set of genes,one could conclude
A)that those genes are not useful in interpreting phylogeny.
B)that Darwin was incorrect in his idea about descent with modification.
C)that the Parazoa are not animals.
D)that those genes probably are related to the embryonic formation of tissues.
E)that those genes are related to cell wall formation.

Accepted Answer

The absence of these particular genes in Parazoa would suggest that they are likely related to the embryonic formation of tissues. This would lead to a better understanding of animal evolution and development. The other options are not necessarily true based on the given information.

Question 4

What is the primary characteristic that groups phyla within the Ecdysozoa?
A)They all have tropchophore larvae.
B)They shed their exoskeletons.
C)They all have spiral cleavage.
D)They all have segmentation.

Accepted Answer

The primary characteristic that groups phyla within the Ecdysozoa is the shedding of their exoskeletons. Ecdysozoa includes phyla such as Arthropoda (insects, crustaceans), Nematoda (roundworms), and Tardigrada (water bears), all of which molt their exoskeletons to grow and develop. The other choices, such as having tropchophore larvae, spiral cleavage, or segmentation, are characteristics found in other groups of animals but not specific to Ecdysozoa.

Question 5

If you conducted an experiment in which you took a complete animal that had no germ layers and strained it through a fine-mesh cloth so that all its cells separated,then you placed all the cells together and they reunited to form a new animal,to which phylum would that animal likely belong? (This was an actual experiment. )
A)Platyhelminthes
B)Porifera
C)Ctenophora
D)Nematoda
E)Arthropoda

Accepted Answer

Porifera, also known as sponges, are the only animals that lack true germ layers. In addition, sponges have pluripotent cells, meaning that they have the ability to differentiate into any cell type, allowing for the regeneration of lost parts and even the entire organism from small fragments. Therefore, if a complete sponge were to be separated into individual cells and those cells were allowed to reintegrate, a new sponge would likely form.

Question 6

If a coelom had been present in a species but was then lost over time,which function would you hypothesize could be most affected?
A)nervous
B)muscular
C)reproductive
D)digestive

Accepted Answer

The coelom, a fluid-filled cavity found in many animals, plays a crucial role in the structure and function of the musculoskeletal system. Its loss would most directly impact the muscular system, as the coelom acts as a hydrostatic skeleton that supports and facilitates muscle contraction and movement.

Question 7

The animal kingdom is a monophyletic grouping.

Accepted Answer

The animal kingdom is monophyletic, meaning that all organisms in this group share a common ancestor and have evolved from a single lineage. This is supported by molecular and morphological evidence.

Question 8

Compare a pseudocoelom to a coelom.
A)A coelom is completely enclosed by mesoderm whereas a pseudocoelom has an outer covering of mesoderm and an inner one of endoderm.
B)A pseudocoelom is completely enclosed by mesoderm whereas a coelom has an outer covering of mesoderm and an inner one of endoderm.
C)The coelom is enclosed by ectoderm and the pseudocoelom is enclosed by endoderm.
D)The pseudocoelom is enclosed by ectoderm and the coelom is enclosed by endoderm.
E)The coelom is enclosed by ectoderm and the pseudocoelom is enclosed by mesoderm.

Accepted Answer

A coelom is completely surrounded by mesoderm whereas a pseudocoelom has an outer covering of mesoderm and an inner one of endoderm.

Question 9

The placement of the phylum Platyhelminthes in the phylogenetic tree differs between a morphologically based phylogeny and a molecular based phylogeny.How do scientists best differentiate the interpretation based on molecular phylogeny?
A)Modern Platyhelminthes do not have a coelom but did originate from an ancestor that had one.
B)The Platyhelminthes clade separated from other clades before coeloms evolved and consequently Platyhelminthes have never had a coelom.
C)Platyhelminthes originated from ancestors with a coelom and have retained it to the present time.
D)Platyhelminthes evolved from an ancestor without a coelom but developed one during the course of their evolution.
E)Some Platyhelminthes have a coelom but others do not and it is difficult to conclude anything about its evolution within the cladE.

Accepted Answer

The answer of The placement of the phylum Platyhelminthes in...

Question 10

Echinoderms are classified as Bilateria,but although they start out as bilateral larvae,they change into radially symmetrical adults.You might hypothesize that their genes controlling the development of radial symmetry are
A)different from those controlling development of symmetry in all other radially symmetrical animals.
B)similar to genes controlling body form in Porifera.
C)similar to genes controlling body form in Ctenophora.
D)similar to genes controlling body form in the lophophorates.
E)similar to a common set of genes controlling body form in Ctenohora,and lophophorates.

Accepted Answer

Echinoderms, despite their adult radial symmetry, are more closely related to bilaterally symmetrical animals than to other radially symmetrical animals. Their genes for radial symmetry likely evolved independently.

Question 11

Suppose you discover a new species of animal that does not have body segments,but is triploblastic,coelomate,and cephalized.Under the molecular phylogenetic scheme,you would allocate it to which phylum?
A)Mollusca
B)Echinodermata
C)Nematoda
D)Platyhelminthes
E)Arthropoda

Accepted Answer

Mollusca is the correct phylum because animals in this group are triploblastic, coelomate, and cephalized, and they do not necessarily have body segments, distinguishing them from segmented phyla like Arthropoda.

Question 12

Ecdysis is
A)development of the ectoderm layer in the gastrulA.
B)development of the epidermis from the ectoderm.
C)disintegration of the ectoderm.
D)molting of the exoskeleton.
E)the feeding tentacles of the Ecdysozoa.

Accepted Answer

Ecdysis refers to the molting of the exoskeleton, which is a characteristic feature of many invertebrates, such as insects, crustaceans, and arachnids. During ecdysis, the old exoskeleton is shed, and a new one is formed, allowing for growth and development.

Question 13

What is a valid distinction between a blastocoel,an archenteron,and a coelom?
A)During development these cavities appear in the sequence blastocoel,archenteron,coelom.
B)The blastocoel forms the cavity of the digestive tract,the archenteron forms the chest cavity,and the coelom forms the cavity of the digestive tract.
C)The coelom is bounded only by an external germ layer,the archenteron is bounded by inner and outer layers of germ cells,and the blastocoel is a cavity within the mesoderm.
D)The coelom has a direct opening to the outside of the embryo whereas the other two cavities do not.

Accepted Answer

The blastocoel is the first cavity that forms during early embryonic development, followed by the formation of the archenteron, which eventually develops into the digestive tract, and finally, the coelom, which forms body cavities such as the thoracic and abdominal cavities. This sequence reflects the typical progression of cavity formation during embryogenesis.

Question 14

A pseudocoelom is a cavity that develops into the coelom during embryonic development.

Accepted Answer

A pseudocoelom is a body cavity that is not entirely lined with mesoderm, and does not develop into a true coelom during embryonic development. True coeloms are lined with mesoderm, which differentiates into the tissues that give rise to muscles and other organs.

Question 15

A hydrostatic skeleton has no bones or cartilage.

Accepted Answer

A hydrostatic skeleton consists of a fluid-filled cavity surrounded by muscle tissue, which generates the necessary pressure to support and move the body. Therefore, there are no bones or cartilage in this type of skeleton.

Question 16

If two otherwise dissimilar organisms share similar genomic DNA,to what would you attribute the genomic similarity?
A)The shared genes are ancient and probably no longer function within the altered physiological states of modern organisms.
B)The shared genes have evolved a number of times and have no phylogenetic significance.
C)The two taxa are more closely related than formerly believed.
D)The shared genes developed early in evolution and are likely to be applicable to a wide diversity of organisms.
E)DNA is not a reliable basis for phylogenetic decisions.

Accepted Answer

Similar genomic DNA suggests a close evolutionary relationship between the two organisms. It is possible that they are more closely related than previously thought, and share a common ancestor in their evolutionary history.

Question 17

An acoelomate is an animal that
A)has a coelom.
B)has a pseudocoelom.
C)has both a coelom and a pseudocoelom.
D)has neither a coelom nor a pseudocoelom.
E)has a coelom during early development but later loses it.

Accepted Answer

An acoelomate is an animal that lacks both a true coelom and a pseudocoelom. These animals have a solid body without a fluid-filled cavity. Examples of acoelomates include flatworms and tapeworms.

Question 18

What phyla of animals has the greatest number of species?
A)Arthropoda
B)Chordata
C)Mollusca
D)Annelida
E)Nematoda

Accepted Answer

Arthropoda is the phylum with the greatest number of species, including insects, spiders, crustaceans, and other groups.

Question 19

Gastrulation is the development of the gastrula into an embryo.

Accepted Answer

Gastrulation is the process during early embryonic development that transforms the blastula into a multilayered structure known as the gastrula, not the development of the gastrula into an embryo.

Question 20

The polymerase chain reaction (PCR)is used as a tool for
A)breaking down DNA for analysis.
B)amplifying the amount of DNA to provide a large sample.
C)fragmenting DNA into smaller pieces.
D)rearranging the gene sequences in isolated fragments of DNA.
E)extracting DNA from nuclei.

Accepted Answer

PCR is primarily used to amplify a specific segment of DNA, producing a large quantity of that particular DNA sequence.

The other options are not accurate. A is incorrect because PCR does not break down DNA, rather it copies it. C is incorrect because PCR does not fragment DNA, it amplifies a specific segment. D is incorrect because PCR does not rearrange gene sequences, it copies them. E is incorrect because PCR does not extract DNA, it amplifies it.

Quiz 25: Animal Diversity: Invertebrates

You are examining a new animal species.You find that you can pass a line through any longitudinal plane and find equal halves.Evaluate the symmetry of this animal.

What does the mesoderm have to do with the designation of a true coelom?

If it were found that all animals except the Parazoa had a particular set of genes,one could conclude

What is the primary characteristic that groups phyla within the Ecdysozoa?

If a coelom had been present in a species but was then lost over time,which function would you hypothesize could be most affected?

The animal kingdom is a monophyletic grouping.

Compare a pseudocoelom to a coelom.

The placement of the phylum Platyhelminthes in the phylogenetic tree differs between a morphologically based phylogeny and a molecular based phylogeny.How do scientists best differentiate the interpretation based on molecular phylogeny?

Echinoderms are classified as Bilateria,but although they start out as bilateral larvae,they change into radially symmetrical adults.You might hypothesize that their genes controlling the development of radial symmetry are

Suppose you discover a new species of animal that does not have body segments,but is triploblastic,coelomate,and cephalized.Under the molecular phylogenetic scheme,you would allocate it to which phylum?

Ecdysis is

What is a valid distinction between a blastocoel,an archenteron,and a coelom?

A pseudocoelom is a cavity that develops into the coelom during embryonic development.

A hydrostatic skeleton has no bones or cartilage.

If two otherwise dissimilar organisms share similar genomic DNA,to what would you attribute the genomic similarity?

An acoelomate is an animal that

What phyla of animals has the greatest number of species?

Gastrulation is the development of the gastrula into an embryo.

The polymerase chain reaction (PCR) is used as a tool for