Question 1

Why are traditional grouping such as Reptilia and Agnatha not recognized in cladistics? Explain why that does or does not make evolutionary sense.

Accepted Answer

Traditional groupings such as Reptilia and Agnatha are not recognized in cladistics because they are not monophyletic, meaning they do not include all descendants of a common ancestor. In cladistics, groups are defined based on shared derived characteristics, and if a group does not share a common ancestor and all of its descendants, it is not considered a valid clade.

For example, the traditional group Reptilia includes animals like snakes, lizards, and crocodiles, but it excludes birds, which are also descendants of the common ancestor of reptiles. Similarly, Agnatha includes jawless fish like lampreys and hagfish, but it excludes jawed fish, which are also descendants of the common ancestor of all fish.

From an evolutionary perspective, it makes sense not to recognize these traditional groupings in cladistics because they do not accurately represent the evolutionary relationships between organisms. By using cladistics to define groups based on shared derived characteristics, we can create more accurate and meaningful classifications that reflect the true evolutionary history of organisms. This allows for a better understanding of the relationships between different species and their shared ancestry.

Question 2

Chordates typically have

Accepted Answer

A) a notochord. 
B) radial cleavage. 
C) the anus derived from the blastopore. 
D) a coelom that is either enterocoelous or schizocoelous. 
E) all of the choices are typical chordate features. 
A) a notochord. 
B) radial cleavage. 
C) the anus derived from the blastopore. 
D) a coelom that is either enterocoelous or schizocoelous. 
E) all of the choices are typical chordate features. E

Question 3

Describe the core difference between the traditional and cladistic classification systems as they relate to chordates.

Accepted Answer

The core difference between the traditional and cladistic classification systems as they relate to chordates lies in their approach to categorizing and organizing species.

In the traditional classification system, organisms are grouped based on their overall similarities in physical characteristics and traits. This system often relies on subjective judgments and does not necessarily reflect the evolutionary relationships between species. For example, in the traditional system, a bird and a bat may be classified together as flying animals due to their similar ability to fly, despite their distinct evolutionary histories.

On the other hand, the cladistic classification system focuses on evolutionary relationships and common ancestry. It groups organisms based on shared derived characteristics, or synapomorphies, that are inherited from a common ancestor. This approach aims to create a more accurate and objective representation of the evolutionary history of species. For chordates, this means that organisms are classified based on their shared characteristics that are unique to the chordate lineage, such as the presence of a notochord and a dorsal nerve cord.

Overall, the core difference between the traditional and cladistic classification systems in relation to chordates is the emphasis on overall similarities versus evolutionary relationships and common ancestry. The cladistic system provides a more accurate and objective representation of the evolutionary history of chordates, while the traditional system may result in grouping organisms based on superficial similarities rather than their true evolutionary relationships.

Question 4

The earliest known vertebrate fossil,from the Burgess Shale of British Columbia,is an amphioxus-like creature called _______.

Accepted Answer

The answer of The earliest known vertebrate fossil,from the Burgess...

Question 5

The phylum Urochordata includes the classes

Accepted Answer

A) Ascidiacea,Cephalaspidomorphi,and Myxini. 
B) Appendicularia,Cephalochordacea,and Myxini. 
C) Ascidiacea,Myxini,and Thaliacea. 
D) Thaliacea,Cephalaspidomorphi,and Calcichordata. 
E) Ascidiacea,Appendicularia,and Thaliacea. 
A) Ascidiacea,Cephalaspidomorphi,and Myxini. 
B) Appendicularia,Cephalochordacea,and Myxini. 
C) Ascidiacea,Myxini,and Thaliacea. 
D) Thaliacea,Cephalaspidomorphi,and Calcichordata. 
E) Ascidiacea,Appendicularia,and Thaliacea.

Question 6

The larva of the freshwater lamprey,that closely resembles the amphioxus lancelet,is the

Accepted Answer

A) Ammocoete. 
B) Branchiostoma. 
C) Cephalaspidomorph. 
D) Heterostracan. 
E) Ostracoderm. 
A) Ammocoete. 
B) Branchiostoma. 
C) Cephalaspidomorph. 
D) Heterostracan. 
E) Ostracoderm.

Question 7

The oldest jawed fishes are extinct and are called ____________.

Accepted Answer

The answer of The oldest jawed fishes are extinct and...

Question 8

Tunicates belong to the subphylum ______________ (Tunicata).

Accepted Answer

The answer of Tunicates belong to the subphylum ______________ (Tunicata)....

Question 9

Pelagic tunicates with barrel-shaped bodies and complex life histories belong to the class _________.

Accepted Answer

The answer of Pelagic tunicates with barrel-shaped bodies and complex...

Question 10

Modification of the pharyngeal slits for first use in respiration occurred in early

Accepted Answer

A) fish with the development of gills. 
B) amphibians with the development of external gills. 
C) reptiles with the development of the modern lung. 
D) lophophorates well before we reach the chordates. 
E) echinoderms as a new respiratory apparatus. 
A) fish with the development of gills. 
B) amphibians with the development of external gills. 
C) reptiles with the development of the modern lung. 
D) lophophorates well before we reach the chordates. 
E) echinoderms as a new respiratory apparatus.

Question 11

Reproduction in sea squirts is

Accepted Answer

A) asexual,with new individuals budding off the adults. 
B) hermaphroditic with internal fertilization. 
C) hermaphroditic with external fertilization. 
D) with separate sexes and internal fertilization. 
E) with separate sexes and external fertilization. 
A) asexual,with new individuals budding off the adults. 
B) hermaphroditic with internal fertilization. 
C) hermaphroditic with external fertilization. 
D) with separate sexes and internal fertilization. 
E) with separate sexes and external fertilization.

Question 12

The extant group likely to be the most closely related to the basal chordates are the echinoderms because

Accepted Answer

A) there is direct fossil evidence for a lineage from sea stars to tunicates. 
B) tunicates are advanced echinoderms. 
C) early embryonic development of echinoderms is similar to that of chordates. 
D) although there are few similarities between echinoderms and chordates,there are even fewer between chordates and any other group. 
E) new molecular evidence shows they are nearly identical at the rRNA level. 
A) there is direct fossil evidence for a lineage from sea stars to tunicates. 
B) tunicates are advanced echinoderms. 
C) early embryonic development of echinoderms is similar to that of chordates. 
D) although there are few similarities between echinoderms and chordates,there are even fewer between chordates and any other group. 
E) new molecular evidence shows they are nearly identical at the rRNA level.

Question 13

The jawless vertebrates are called Agnatha,and the jawed vertebrates are called __________________.

Accepted Answer

The answer of The jawless vertebrates are called Agnatha,and the...

Question 14

The difference(s)between the traditional and cladistic classification of chordates and their extant sister groups is a difference in

Accepted Answer

A) the addition of new and comparative rRNA and DNA molecular sequence data. 
B) fossil evidence that clearly shows that the traditional classification is simply wrong. 
C) the insistence in traditional systematics that all taxa be paraphyletic. 
D) the insistence in cladistics that all taxa be monophyletic. 
E) all of the choices are points of argument. 
A) the addition of new and comparative rRNA and DNA molecular sequence data. 
B) fossil evidence that clearly shows that the traditional classification is simply wrong. 
C) the insistence in traditional systematics that all taxa be paraphyletic. 
D) the insistence in cladistics that all taxa be monophyletic. 
E) all of the choices are points of argument.

Question 15

Discuss the contention that the ammocoete larva of lampreys is a successful model of the primitive vertebrate body plan.

Accepted Answer

The ammocoete larva of lampreys has been

Question 16

A dorsal tubular nerve cord is

Accepted Answer

A) another name for the notochord. 
B) a strip of cartilage that forms a back and tail. 
C) primitive tissue that forms bone vertebrae. 
D) an early nerve cord that enlarges at one end to form the brain and also extends through vertebrae. 
E) None of the choices is correct. 
A) another name for the notochord. 
B) a strip of cartilage that forms a back and tail. 
C) primitive tissue that forms bone vertebrae. 
D) an early nerve cord that enlarges at one end to form the brain and also extends through vertebrae. 
E) None of the choices is correct.

Question 17

Salps in the class Thalacea

Accepted Answer

A) are barrel-shaped open-ocean organisms. 
B) have larger transparent bodies. 
C) may be luminous at night. 
D) may occur singly or in long chains. 
E) All of the choices are correct. 
A) are barrel-shaped open-ocean organisms. 
B) have larger transparent bodies. 
C) may be luminous at night. 
D) may occur singly or in long chains. 
E) All of the choices are correct.

Question 18

The central definition of a monophyletic group focuses on:

Accepted Answer

A) Do we have evidence of transitional fossils in the geological record? 
B) Do we have the majority of species described in each higher taxon? 
C) Are all of the species described actually real species? 
D) Do all higher taxa contain all known descendants of their single common ancestor? 
E) Do all of the taxa fit into the seven ranks of the Linnaean taxonomic hierarchy? 
A) Do we have evidence of transitional fossils in the geological record? 
B) Do we have the majority of species described in each higher taxon? 
C) Are all of the species described actually real species? 
D) Do all higher taxa contain all known descendants of their single common ancestor? 
E) Do all of the taxa fit into the seven ranks of the Linnaean taxonomic hierarchy?

Question 19

The urochordates are

Accepted Answer

A) called tunicates. 
B) marine animals. 
C) sessile as adults,but tadpole-like as larvae. 
D) often abundant in intertidal organisms. 
E) All of the choices are correct. 
A) called tunicates. 
B) marine animals. 
C) sessile as adults,but tadpole-like as larvae. 
D) often abundant in intertidal organisms. 
E) All of the choices are correct.

Question 20

Development of the vertebrate head and sense organs was largely the result of two innovations:

Accepted Answer

A) Appearance of an outer epidermis and an inner dermis 
B) Neural crest and ectodermal placodes 
C) Living endoskeleton and highly differentiated brain 
D) 10 to 12 pairs of cranial nerves and an autonomic nervous system 
E) Pharynx and endocrine system 
A) Appearance of an outer epidermis and an inner dermis 
B) Neural crest and ectodermal placodes 
C) Living endoskeleton and highly differentiated brain 
D) 10 to 12 pairs of cranial nerves and an autonomic nervous system 
E) Pharynx and endocrine system

Exam 23: Chordates

Why are traditional grouping such as Reptilia and Agnatha not recognized in cladistics? Explain why that does or does not make evolutionary sense.

Chordates typically have

Describe the core difference between the traditional and cladistic classification systems as they relate to chordates.

The earliest known vertebrate fossil,from the Burgess Shale of British Columbia,is an amphioxus-like creature called _______.

The phylum Urochordata includes the classes

The larva of the freshwater lamprey,that closely resembles the amphioxus lancelet,is the

The oldest jawed fishes are extinct and are called ____________.

Tunicates belong to the subphylum ______________ (Tunicata).

Pelagic tunicates with barrel-shaped bodies and complex life histories belong to the class _________.

Modification of the pharyngeal slits for first use in respiration occurred in early

Reproduction in sea squirts is

The extant group likely to be the most closely related to the basal chordates are the echinoderms because

The jawless vertebrates are called Agnatha,and the jawed vertebrates are called __________________.

The difference(s)between the traditional and cladistic classification of chordates and their extant sister groups is a difference in

Discuss the contention that the ammocoete larva of lampreys is a successful model of the primitive vertebrate body plan.

A dorsal tubular nerve cord is

Salps in the class Thalacea

The central definition of a monophyletic group focuses on:

The urochordates are

Development of the vertebrate head and sense organs was largely the result of two innovations:

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