What is the field that studies organisms in order to work out their evolutionary relationships?
Systematics
✓
Ecology
Embryology
Physiology
Correct Answer
Systematics
Systematics uses fossils, body structure and molecular data to determine how organisms are related and to build phylogenetic trees. Ecology studies how organisms interact with each other and their environment. Embryology studies how organisms develop before birth or hatching. Physiology studies how body parts and systems function.
Category: Phylogeny and Systematics
Question 2
Which list puts these Linnaean levels in order from most inclusive to least inclusive?
Class, phylum, order, family
Phylum, class, order, family
✓
Phylum, order, class, family
Family, order, class, phylum
Correct Answer
Phylum, class, order, family
From most to least inclusive, the Linnaean levels run domain, kingdom, phylum, class, order, family, genus and species, so phylum, class, order, family is correct. Class, phylum, order, family swaps the first two levels. Phylum, order, class, family swaps class and order. Family, order, class, phylum lists the levels in reverse, from least to most inclusive.
Category: Levels of Classification
Question 3
Which level of the Linnaean hierarchy holds the largest, most inclusive groups of organisms?
Kingdom
Phylum
Domain
✓
Species
Correct Answer
Domain
Domain is the top level, and the three domains, Bacteria, Archaea and Eukarya, each contain all the lower groups. Kingdom is the next level down; the domain Eukarya, for example, contains several kingdoms such as plants, animals and fungi. Phylum sits below kingdom. Species is the least inclusive level, at the bottom of the hierarchy.
Category: Levels of Classification
Question 4
Domestic dogs and cats are classified in the same order, Carnivora. At which level are they first placed in different groups?
Genus
Species
Subspecies
Family
✓
Correct Answer
Family
Dogs belong to the family Canidae and cats to the family Felidae, so the family level is the first place their classifications split. Genus is below family, so by the time it is reached they are already in separate groups. Species is lower still. Subspecies is the narrowest category and is far below the point where they diverge.
Category: Levels of Classification
Question 5
Biologists often build separate trees from different gene sequences for the same organisms. Why do they check whether these trees match?
Agreement raises confidence in the relationships
✓
Each gene must show a different set of species
Matching trees prove branch lengths equal time
Only one gene can be sequenced per species
Correct Answer
Agreement raises confidence in the relationships
When trees built from independent gene sequences show the same branching pattern, it is unlikely the pattern arose by chance, so confidence in those relationships increases. Each gene must show a different set of species is false, since the same organisms are compared. Matching trees prove branch lengths equal time is wrong, because branch lengths do not show time unless a tree is drawn to scale. Only one gene can be sequenced per species is false, as many genes are routinely compared.
Category: Molecular Systematics
Question 6
Since the 1800s, biologists have aimed for classification groups that reflect which of these?
Similar habitats and diets
Shared evolutionary ancestry
✓
Similar body size and color
The order of their discovery
Correct Answer
Shared evolutionary ancestry
After Darwin, classification has aimed to group organisms that share a common ancestor and are more closely related to each other than to members of other groups. Similar habitats and diets can be shared by unrelated organisms. Similar body size and color are superficial traits that can arise independently. The order of their discovery says nothing about relatedness.
Category: Levels of Classification
Question 7
On a phylogenetic tree, what does a branch point represent?
A species that is alive today
The number of years between events
One lineage splitting into new lineages
✓
A group that left no descendants
Correct Answer
One lineage splitting into new lineages
A branch point marks where a single ancestral lineage split and evolved into distinct new lineages. A species that is alive today is shown at the tip of a branch, not at a branch point. The number of years between events is not shown unless the tree is drawn to a time scale. A group that left no descendants would end without branching.
Category: Phylogenetic Trees
Question 8
What are two lineages called when they arise from the same branch point?
Outgroups
Polytomies
Root lineages
Sister taxa
✓
Correct Answer
Sister taxa
Sister taxa share an immediate common ancestor at one branch point, like humans and chimpanzees. Outgroups are lineages that split off earlier and are used for comparison. Polytomies are branch points with more than two lineages. Root lineages refers to the ancestral base of a tree, not a pair of descendants.
Category: Phylogenetic Trees
Question 9
What do biologists call a branch point with three or more lineages, drawn when the exact relationships among them are not yet known?
Polytomy
✓
Clade
Root
Outgroup
Correct Answer
Polytomy
A polytomy shows several lineages emerging from one point because the order in which they split has not been resolved. Clade is a group made of an ancestor and all its descendants. Root is the ancestral lineage at the base of a tree. Outgroup is an earlier-diverging lineage used for comparison.
Category: Phylogenetic Trees
Question 10
Which statement correctly describes how humans and chimpanzees are related?
Humans evolved from modern chimpanzees
Both descend from an extinct shared ancestor
✓
Chimpanzees evolved from early humans
They share no common ancestor at all
Correct Answer
Both descend from an extinct shared ancestor
Humans and chimpanzees are close living relatives that both descend from a common ancestor that lived millions of years ago and differed from both. Humans evolved from modern chimpanzees is a common misreading of trees. Chimpanzees evolved from early humans makes the same mistake in reverse. They share no common ancestor at all is false, since all life shares common ancestry.
Category: Phylogenetic Trees
Question 11
Unless a phylogenetic tree is drawn to a time scale, what information does it reliably show?
The years between each split
How alike the species look
The order in which lineages split
✓
The population size of each species
Correct Answer
The order in which lineages split
A standard tree shows the sequence of branching events, so it tells which lineages split earlier or later. The years between each split are shown only when the tree is drawn to a time scale. How alike the species look is not shown, since closely related species can look very different. The population size of each species is not part of a phylogenetic tree.
Category: Limits of Phylogenetic Trees
Question 12
Lizards are more closely related to rabbits than to salamanders, yet lizards look more like salamanders. What does this show?
Lizards and salamanders share amniotic eggs
Rabbits evolved directly from lizards
Branch lengths on trees show elapsed time
Close relatives do not always look most alike
✓
Correct Answer
Close relatives do not always look most alike
Lineages that evolved in different environments or after a major adaptation can look quite different, so close relationship does not guarantee similar appearance. Lizards and salamanders share amniotic eggs is false, because salamanders lack the amniotic egg that lizards and rabbits share. Rabbits evolved directly from lizards is false, since they share an ancestor instead. Branch lengths on trees show elapsed time is not true of most trees and is unrelated to this example.
Category: Limits of Phylogenetic Trees
Question 13
Which pair of structures is homologous?
A human arm and a whale flipper
✓
A bird wing and an insect wing
A bat wing and a moth wing
A fly wing and a hummingbird wing
Correct Answer
A human arm and a whale flipper
A human arm and a whale flipper contain the same set of bones in a similar arrangement, inherited from a common ancestor, even though their shapes differ. A bird wing and an insect wing do the same job but have different embryonic origins. A bat wing and a moth wing are likewise similar only in function. A fly wing and a hummingbird wing also evolved independently.
Category: Homologous and Analogous Traits
Question 14
Why must biologists decide whether a similarity is homologous or analogous before using it to build a phylogenetic tree?
Only analogous traits are inherited
Only homologous traits reflect shared ancestry
✓
Homologous traits always change faster
Analogous traits occur only in plants
Correct Answer
Only homologous traits reflect shared ancestry
Homologous traits are similar because they were inherited from a common ancestor, so they reveal relationships, while analogous traits arise independently and can make unrelated organisms look related. Only analogous traits are inherited is false, since both kinds are heritable. Homologous traits always change faster has no basis. Analogous traits occur only in plants is false, as insect and bird wings show.
Category: Homologous and Analogous Traits
Question 15
To compare very distantly related groups, such as Eukarya and Archaea, which kind of gene sequence is most useful?
One that changes very rapidly
One found only in eukaryotes
One that changes very slowly over time
✓
One found only in animals
Correct Answer
One that changes very slowly over time
Slowly evolving sequences, such as genes for ribosomal RNA, still retain recognizable similarity after very long periods, so they can link distant groups. One that changes very rapidly is better for closely related species, because in distant groups it has changed too much to compare. One found only in eukaryotes cannot be compared with Archaea. One found only in animals is absent from both groups in question.
Category: Molecular Systematics
Question 16
In a cladistic analysis of lizards, rabbits and humans, lampreys are included as a lineage that split off earlier. What is this comparison lineage called?
Ingroup
Polytomy
Derived lineage
Outgroup
✓
Correct Answer
Outgroup
An outgroup is a lineage that diverged before the group being studied and is used to tell which character states are ancestral. Ingroup refers to the taxa being analyzed, here lizards, rabbits and humans. Polytomy is a branch point with more than two lineages. Derived lineage is not the term for the comparison group in cladistics.
Category: Cladistics
Question 17
Within vertebrates, the amniotic egg is present in lizards, rabbits and humans but absent in fish and lampreys. For this set of animals, what kind of character is the amniotic egg?
Shared derived character
✓
Shared ancestral character
Analogous character
Vestigial character
Correct Answer
Shared derived character
A shared derived character appeared in a common ancestor of only some members of a group, so it marks lizards, rabbits and humans as a clade apart from fish and lampreys. Shared ancestral character would be present in all the animals compared. Analogous character arises independently, while the amniotic egg was inherited from one ancestor. Vestigial character refers to a leftover structure with no apparent function.
Category: Cladistics
Question 18
Which principle selects the phylogenetic tree that explains the data with the fewest evolutionary changes?
Binomial nomenclature
Maximum parsimony
✓
Molecular clock
Hardy-Weinberg equilibrium
Correct Answer
Maximum parsimony
Maximum parsimony assumes events happened in the simplest way, so the preferred tree has the fewest total changes, independent origins and reversals. Binomial nomenclature is the two-part naming system for species. Molecular clock uses mutation rates to estimate when lineages split. Hardy-Weinberg equilibrium describes stable allele frequencies in a population, not tree building.
Category: Cladistics
Question 19
A 2010 phylogenetic study of MRSA, an antibiotic-resistant bacterium, helped public health officials by showing what?
Which antibiotic cures every MRSA case
That the strain arose anew in each country
How the strain spread between continents
✓
That the strain cannot pass between people
Correct Answer
How the strain spread between continents
By building a tree of MRSA samples, researchers traced its spread over about 40 years from Europe to other continents and found it entered new populations only a few times, so tracing contacts of new cases is worthwhile. Which antibiotic cures every MRSA case was not something a phylogeny can show. That the strain arose anew in each country is the opposite of the finding. That the strain cannot pass between people is false, since the study tracked its spread.
Category: Molecular Systematics
Question 20
A 2007 study ranked mammals for conservation by evolutionary distinctiveness as well as threat. Why did some little-known shrews and bats rank highly?
They are the most threatened mammals
They are the largest living mammals
They are the best-studied mammals
They have few close living relatives
✓
Correct Answer
They have few close living relatives
Evolutionarily distinct species sit on long, isolated branches of the tree, so losing them would erase a large share of unique evolutionary history. They are the most threatened mammals is wrong, since some critically endangered rodents ranked lower. They are the largest living mammals does not describe shrews and bats. They are the best-studied mammals is wrong, as they were noted for being little known.
Category: Molecular Systematics