Question 1

Which individual would make the worst systematist? One who is uncomfortable with the
A)Linnaean system of classification.
B)notion of hypothetical phylogenies.
C)PhyloCode method of classification.
D)notion of permanent polytomies.

Accepted Answer

Systematics is based on the idea of evolutionary relationships and uses hypothetical phylogenies to classify organisms. If someone is uncomfortable with this notion, they would not make a good systematist.

Question 2

There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then what can be properly said of hair?
A)It is a shared derived character of mammals, even if cynodonts continue to be classified as reptiles.
B)It is a shared derived character of the amniote clade, and not of the mammal clade.
C)It is a shared ancestral character of the amniote clade, but only if cynodonts are reclassified as mammals.
D)It is a shared derived character of the mammals, but only if cynodonts are reclassified as mammals.

Accepted Answer

D

Question 3

Which of the following is (are)problematic when the goal is to construct phylogenies that accurately reflect evolutionary history?
A)polyphyletic taxa
B)paraphyletic taxa
C)monophyletic taxa
D)Two of the responses are correct.

Accepted Answer

Polyphyletic and paraphyletic taxa are problematic for constructing accurate phylogenies because they do not represent natural groups derived from a common ancestor. Polyphyletic groups consist of species with similar characteristics but different ancestors, while paraphyletic groups include some, but not all, descendants of a common ancestor. Monophyletic taxa, which include an ancestor and all its descendants, are ideal for reflecting evolutionary history.

Question 4

Linnaeus was a "fixist" who believed that species remained fixed in the form in which they had been created. Linnaeus would have been uncomfortable with
A)classifying organisms using the morphospecies concept.
B)the scientific discipline known as taxonomy.
C)phylogenies.
D)nested, ever-more inclusive categories of organisms.
E)a hierarchical classification scheme.

Accepted Answer

Linnaeus believed that species were fixed and did not change over time. This would mean that he would reject the idea of phylogenies, which show how species have evolved and changed over time through common ancestry.

Question 5

Cladograms (a type of phylogenetic tree)constructed from evidence from molecular systematics are based on similarities in
A)morphology.
B)the pattern of embryological development.
C)biochemical pathways.
D)habitat and lifestyle choices.
E)mutations to homologous genes.

Accepted Answer

Cladograms constructed from molecular systematics are based on similarities in mutations to homologous genes. This involves comparing the DNA or amino acid sequences of specific genes across different species. This method allows for a more precise and objective analysis of evolutionary relationships, as the genetic code is less susceptible to environmental or developmental variation.

Question 6

The various taxonomic levels (namely, genera, classes, etc.)of the hierarchical classification system differ from each other on the basis of
A)how widely the organisms assigned to each are distributed throughout the environment.
B)their inclusiveness.
C)the relative genome sizes of the organisms assigned to each.
D)morphological characters that are applicable to all organisms.

Accepted Answer

The taxonomic levels differ from each other on the basis of their inclusiveness, in the sense that each level includes a certain group of organisms that share a set of characteristics that distinguish them from groups assigned to other levels.

Question 7

The common ancestors of birds and mammals were very early (stem)reptiles, which almost certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). The? four-chambered hearts of birds and mammals are best described as
A)structural homologies.
B)vestiges.
C)homoplasies.
D)the result of shared ancestry.
E)molecular homologies.

Accepted Answer

The four-chambered hearts of birds and mammals are best described as homoplasies, which means they are similar structures that evolved independently in the two lineages after their divergence from a common ancestor with a three-chambered heart. This is not due to direct inheritance from a common ancestor with a four-chambered heart (which would be shared ancestry), but rather convergent evolution where similar environmental pressures led to the development of similar structures.

Question 8

The domestic dog, red fox, and wolf belong to the family Canidae. The dog is Canis lupus familiaris, the red fox is Vulpes vulpes, and the wolf is Canis lupus. Which of the following statements is correct?
A)All three canids are in different genera.
B)The red fox is in the same family, but of a different genus, than wolves and dogs.
C)All three canids should successfully breed with one another.
D)All three belong to the same genera but are different species.
E)All three canids live on different continents.

Accepted Answer

The red fox is in the same family as wolves and dogs, but of a different genus. Dogs and wolves are in the same genus, Canis, while the red fox is in the genus Vulpes. Therefore, option A and D are incorrect. Option C is incorrect because while dogs and wolves are capable of interbreeding, foxes cannot interbreed with them. Option E is also incorrect as all three canids are found in different parts of the world, but not necessarily on different continents.

Question 9

Which mutation should least require realignment of homologous regions of a gene that is common to several related species?
A)three-base insertion
B)one-base substitution
C)four-base insertion
D)one-base deletion
E)three-base deletion

Accepted Answer

A one-base substitution involves replacing one nucleotide with another, which should not significantly alter the length of the gene or require realignment of homologous regions. The other options all involve changes in the length of the gene, which could cause frameshifts and require realignment of homologous regions.

Question 10

If, someday, an archaean cell is discovered whose rRNA sequence is more similar to that of humans than the sequence of mouse rRNA is to that of humans, the best explanation for this apparent discrepancy would be
A)homology.
B)homoplasy.
C)common ancestry.
D)retro-evolution by humans.
E)coevolution of humans and that archaean.

Accepted Answer

Homoplasy refers to a similarity in the structure or genetic sequence of different species that is due to convergent evolution rather than to descent from a common ancestor. In the scenario described, the surprising similarity between human rRNA and that of an archaean cell, more so than between humans and mice, would likely be due to convergent evolution (homoplasy), rather than direct common ancestry. This is because archaea and humans are very distantly related on the evolutionary tree, with mice being much closer relatives to humans.

Question 11

Which of the following pairs are the best examples of homologous structures?
A)bones in the bat wing and bones in the human forelimb
B)owl wing and hornet wing
C)bat wing and bird wing
D)eyelessness in the Australian mole and eyelessness in the North American mole

Accepted Answer

Bones in the bat wing and bones in the human forelimb are the best examples of homologous structures because they have the same basic structure and arrangement, even though they have different functions. This suggests that they were inherited from a common ancestor. Owls and hornets, bats and birds, and eyelessness in moles are not examples of homologous structures.

Question 12

The best classification system is that which most closely
A)unites organisms that possess similar morphologies.
B)conforms to traditional, Linnaean taxonomic practices.
C)reflects evolutionary history.
D)reflects the basic separation of prokaryotes from eukaryotes.

Accepted Answer

A classification system that reflects evolutionary history is generally considered the best because it allows for the grouping of organisms based on their shared ancestry and genetic relationships. This can provide insight into the evolutionary relationships among different groups of organisms and help to better understand their biological and ecological characteristics. Morphologies and Linnaean taxonomic practices may not always reflect these relationships accurately. The separation of prokaryotes and eukaryotes is important but only represents a small aspect of the overall evolutionary history of life.

Question 13

Which of the following is true of all horizontally oriented phylogenetic trees, where time advances to the right?
A)Each branch point represents a point in absolute time.
B)Organisms represented at the base of such trees are descendants of those represented at higher levels.
C)The fewer branch points that occur between two taxa, the more divergent their DNA sequences should be.
D)The common ancestor represented by the rightmost branch point existed more recently in time than the common ancestors represented at branch points located to the left.
E)The more branch points there are, the fewer taxa are likely to be represented.

Accepted Answer

In horizontally oriented phylogenetic trees, time advances to the right, meaning that the common ancestor represented by the rightmost branch point is the most recent one. All other ancestors, represented at branch points to the left, existed further back in time.

Question 14

Consider the human arm, a dog's foreleg, and a seal's flipper. These three structures are examples of ________ structures.
A)analogous
B)homologous
C)mammalian
D)similar function in
E)related

Accepted Answer

These structures are examples of homologous structures because they share a common evolutionary origin and are similar in basic structure but have adapted to different functions.

Question 15

The legless condition that is observed in several groups of extant reptiles is the result of
A)their common ancestor having been legless.
B)a shared adaptation to an arboreal (living in trees)lifestyle.
C)several instances of the legless condition arising independently of each other.
D)individual lizards adapting to a fossorial (living in burrows)lifestyle during their lifetimes.

Accepted Answer

The legless condition has arisen independently in several different groups of reptiles, indicating that it is the result of convergent evolution rather than a shared ancestry or adaptation to a specific lifestyle.

Question 16

The importance of computers and of computer software to modern cladistics is most closely linked to advances in
A)light microscopy.
B)radiometric dating.
C)fossil discovery techniques.
D)Linnaean classification.
E)molecular genetics.

Accepted Answer

Computer software has revolutionized cladistics through its ability to analyze large amounts of DNA and other molecular data quickly and accurately. This has led to a greater understanding of the relationships and evolutionary history of organisms. While advances in other fields, such as light microscopy and fossil discovery techniques, have also contributed to our understanding of evolutionary relationships, the importance of computers and software cannot be overstated.

Question 17

Some molecular data place the giant panda in the bear family (Ursidae)but place the lesser panda in the raccoon family (Procyonidae). Consequently, the morphological similarities of these two species are probably due to
A)inheritance of acquired characteristics.
B)sexual selection.
C)inheritance of shared derived characters.
D)possession of analogous structures.
E)possession of shared primitive characters.

Accepted Answer

The morphological similarities between the giant panda and the lesser panda, despite their placement in different families based on molecular data, suggest that these similarities are due to analogous structures. Analogous structures arise from convergent evolution, where unrelated species develop similar traits independently, often due to similar environmental pressures or ecological roles, rather than from a common ancestor.

Question 18

The term homoplasy is most applicable to which of the following features?
A)the legless condition found in various lineages of extant lizards
B)the five-digit condition of human hands and bat wings
C)the β hemoglobin genes of mice and of humans
D)the fur that covers Australian moles and North American moles
E)the bones of bat forelimbs and the bones of bird forelimbs

Accepted Answer

Homoplasy refers to the independent evolution of similar features in unrelated lineages, and the legless condition found in various lineages of extant lizards is a clear example of homoplasy. The other options either involve homology (shared ancestry) or are not clear examples of homoplasy.

Question 19

If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?
A)A and B
B)A and C
C)B and D
D)C and F
E)D and F

Accepted Answer

Organisms D and F are in the same order and thus would be expected to have a higher degree of structural homology than organisms in different orders. Therefore, choice E, which pairs organisms D and F, would be expected to show the greatest degree of structural homology.

Question 20

When using a cladistic approach to systematics, which of the following is considered most important for classification?
A)shared primitive characters
B)analogous primitive characters
C)shared derived characters
D)the number of homoplasies
E)overall phenotypic similarity

Accepted Answer

In cladistics, classification is based on shared derived characters, also known as synapomorphies. These are traits that are unique to a particular lineage and have evolved from a common ancestor. Shared primitive characters (A) are traits that are present in multiple lineages but are not unique or informative for classification. Analogous primitive characters (B) are traits that are similar but have evolved independently in different lineages and are therefore not useful for classification. The number of homoplasies (D), or convergent evolution events, is important in assessing the reliability of a cladogram, but it is not the primary factor in classification. Overall phenotypic similarity (E) may be used in some classification methods but is not specific to cladistics.

Quiz 26: Phylogeny and the Tree of Life

Which individual would make the worst systematist? One who is uncomfortable with the

There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then what can be properly said of hair?

Which of the following is (are) problematic when the goal is to construct phylogenies that accurately reflect evolutionary history?

Linnaeus was a "fixist" who believed that species remained fixed in the form in which they had been created. Linnaeus would have been uncomfortable with

Cladograms (a type of phylogenetic tree) constructed from evidence from molecular systematics are based on similarities in

The various taxonomic levels (namely, genera, classes, etc.) of the hierarchical classification system differ from each other on the basis of

The domestic dog, red fox, and wolf belong to the family Canidae. The dog is Canis lupus familiaris, the red fox is Vulpes vulpes, and the wolf is Canis lupus. Which of the following statements is correct?

Which mutation should least require realignment of homologous regions of a gene that is common to several related species?

If, someday, an archaean cell is discovered whose rRNA sequence is more similar to that of humans than the sequence of mouse rRNA is to that of humans, the best explanation for this apparent discrepancy would be

Which of the following pairs are the best examples of homologous structures?

The best classification system is that which most closely

Which of the following is true of all horizontally oriented phylogenetic trees, where time advances to the right?

Consider the human arm, a dog's foreleg, and a seal's flipper. These three structures are examples of ________ structures.

The legless condition that is observed in several groups of extant reptiles is the result of

The importance of computers and of computer software to modern cladistics is most closely linked to advances in

Some molecular data place the giant panda in the bear family (Ursidae) but place the lesser panda in the raccoon family (Procyonidae) . Consequently, the morphological similarities of these two species are probably due to

The term homoplasy is most applicable to which of the following features?

If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F belong to the same order but to different families, which of the following pairs of organisms would be expected to show the greatest degree of structural homology?

When using a cladistic approach to systematics, which of the following is considered most important for classification?