Quiz 11

Question 1

Which of the following statements about species, as defined by the biological species concept, is (are) correct?

I. Biological species are defined by reproductive isolation.
II. Biological species are the model used for grouping extinct forms of life.
III. The biological species is the largest unit of population in which successful interbreeding is possible.

Answer 1

I and III

Question 2

In a hypothetical situation, a certain species of flea feeds only on pronghorn antelopes. In rangelands of the western United States, pronghorns and cattle often associate with one another. If some of these fleas develop a strong preference for cattle blood and mate only with other fleas that prefer cattle blood, then over time which of these should occur, if the host mammal can be considered as the fleas’ habitat?

1. reproductive isolation
2. sympatric speciation
3. habitat isolation
4. prezygotic barriers

Answer 2

1, 2, 3, and 4

Question 3

Which of these should decline in hybrid zones where reinforcement is occurring?

a) gene flow between distinct gene pools
b) speciation
c) mutation rate
d) hybrid sterility

Answer 3

a) gene flow between distinct gene pools

Question 4

Which of the following statements about speciation is correct?

a) The goal of natural selection is speciation.
b) Natural selection chooses the reproductive barriers for populations.
c) Prezygotic reproductive barriers usually evolve before postzygotic barriers.
d) Speciation is a basis for understanding macroevolution.

Answer 4

d) Speciation is a basis for understanding macroevolution.

Question 5

If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (for example, lava, volcanic ash) nearby, then it should be

a) easy to determine the absolute age of the fossil, because the radioisotopes in the sediments will not have been “reset” by the heat of the igneous rocks.
b) easy to determine the absolute age of the fossil, because the igneous rocks will not have physically obstructed the deposition of sediment of a single age next to the fossil.
c) difficult to determine the absolute age of the fossil, because the “marker fossils” common to igneous rock will be absent.
d) difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock.

Answer 5

d) difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock.

Question 6

Which of these observations gives the most support to the endosymbiotic theory for the origin of eukaryotic cells?

a) the existence of structural and molecular differences between the plasma membranes of prokaryotes and the internal membranes of mitochondria and chloroplasts
b) the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts
c) the size disparity between most prokaryotic cells and most eukaryotic cells
d) the observation that some eukaryotic cells lack mitochondria

Answer 6

b) the similarity in size between the cytosolic ribosomes of prokaryotes and the ribosomes within mitochondria and chloroplasts

Question 7

Fossils of Lystrosaurus, a pig-sized, mammal-like reptile, are most common in parts of modern-day South America, South Africa, Madagascar, India, South Australia, and Antarctica. It apparently lived in arid regions, and was mostly herbivorous. It originated during the mid-Permian period, survived the Permian extinction, and dwindled by the late Triassic, though there is evidence of a relict population in Australia during the Cretaceous period. They had two large tusks, extending down from their upper jaws. The tusks were not used for food gathering, and in some species were limited to males. Food was gathered using an otherwise toothless beak. Judging from the fossil record in sedimentary rocks, they were the most common animal of their kind in the Permian period.

If an increase in Lystrosaurus species diversity (in other words, number of species) occurred soon after the Permian extinction, and if it occurred for the same general reason usually given for the increase in mammalian diversity following the Cretaceous extinction, then it should be attributed to

a) an innovation among the Lystrosaurus that allowed them to fill brand-new niches.
b) the availability of previously-occupied niches.
c) the extinction of the dinosaurs (except the birds).
d) their outcompetition of many other terrestrial organisms.

Answer 7

b) the availability of previously-occupied niches.

Question 8

An organism has a relatively large number of Hox genes in its genome. Which of the following is true of this organism?

a) These genes are fundamental, and are expressed in all cells of the organism.
b) The organism must have multiple paired appendages along the length of its body.
c) The organism has the genetic potential to have a relatively complex anatomy.
d) Most of its Hox genes owe their existence to gene fusion events.

Answer 8

c) The organism has the genetic potential to have a relatively complex anatomy.

Question 9

If one organ is an exaptation of another organ, then what must be true of these two organs?

a) They are both vestigial organs.
b) They are both homologous organs.
c) They are undergoing convergent evolution.
d) They have the same function.

Answer 9

b) They are both homologous organs.

Question 10

A narrow hybrid zone separates the toad species Bombina bombina and Bombina variegata. What is true of those alleles that are unique to the parental species?

a) Their allele frequency should be nearly the same as the allele frequencies in toad populations distant from the hybrid zone.
b) Such alleles should be absent.
c) The alleles’ heterozygosity should be higher among the hybrid toads there.
d) Their allele frequency on one edge of the hybrid zone should roughly equal their frequency on the opposite edge of the hybrid zone.

Answer 10

c) The alleles’ heterozygosity should be higher among the hybrid toads there.

Question 11

In order for speciation to occur, what must be true?

a) At least one gene, affecting at least one phenotypic trait, must change.
b) The number of chromosomes in the gene pool must change.
c) Large numbers of genes that affect numerous phenotypic traits must change.
d) Changes to centromere location or chromosome size must occur within the gene pool.
e) Large numbers of genes that affect a single phenotypic trait must change.

Answer 11

a) At least one gene, affecting at least one phenotypic trait, must change.

Question 12

The phenomenon of fusion is likely to occur when, after a period of geographic isolation, two populations meet again and

a) a constant number of viable, fertile hybrids is produced over the course of generations.
b) their chromosomes are no longer homologous enough to permit meiosis.
c) the hybrid zone is inhospitable to hybrid survival.
d) an increasing number of viable, fertile hybrids is produced over the course of generations.
e) a decreasing number of viable, fertile hybrids is produced over the course of generations.

Answer 12

d) an increasing number of viable, fertile hybrids is produced over the course of generations.

Question 13

On the Bahamian island of Andros, mosquitofish populations live in various, now-isolated, freshwater ponds that were once united. Currently, some predator-rich ponds have mosquitofish that can swim in short, fast bursts; other predator-poor ponds have mosquitofish that can swim continuously for a long time. When placed together in the same body of water, the two kinds of female mosquitofish exhibit exclusive breeding preferences.

Which type of reproductive isolation operates to keep the mosquitofish isolated, even when fish from different ponds are reunited in the same body of water?

a) mechanical isolation
b) temporal isolation
c) behavioural isolation
d) gametic isolation
e) habitat isolation

Answer 13

c) behavioural isolation

Question 14

Which of these should decline in hybrid zones where reinforcement is occurring?

a) mutation rate
b) speciation
c) the genetic distinctness of two gene pools
d) gene flow between distinct gene pools
e) hybrid sterility

Answer 14

d) gene flow between distinct gene pools

Question 15

What is thought to be the correct sequence of these events, from earliest to most recent, in the evolution of life on Earth?

1. origin of mitochondria
2. origin of multicellular eukaryotes
3. origin of chloroplasts
4. origin of cyanobacteria
5. origin of fungal-plant symbioses

Answer 15

4, 1, 3, 2, 5

Question 16

Which of the following characteristics should have been possessed by the first animals to colonize land?

1. were probably herbivores (ate photosynthesizers)
2. had four appendages
3. had the ability to resist dehydration
4. had lobe-finned fishes as ancestors
5. were invertebrates

Answer 16

1, 3, and 5

Question 17

The first terrestrial organisms probably were considered which of the following?

1. burrowers
2. photosynthetic
3. multicellular
4. prokaryotes
5. eukaryotes
6. plants and their associated fungi

Answer 17

2 & 4

Question 18

The hypothesis for the origin of eukaryotes through serial endosymbiosis proposes that

a) eukaryotes likely evolved from the fusion of small prokaryotic and small eukaryotic cells.
b) the ancestors of mitochondria were aerobic heterotrophic prokaryotes, while the ancestors of plastids were photosynthetic prokaryotes.
c) genes in mitochondria and plastids are similar to genes of ancient eukaryotes.
d) mitochondria and plastids replicate in a manner similar to eukaryotes.

Answer 18

b) the ancestors of mitochondria were aerobic heterotrophic prokaryotes, while the ancestors of plastids were photosynthetic prokaryotes.

Question 19

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

a) the islands were originally part of the continent.
b) the island forms and mainland forms are converging.
c) island forms and mainland forms have identical gene pools.
d) island forms and mainland forms descended from common ancestors.
e) common environments are inhabited by the same organisms.

Answer 19

d) island forms and mainland forms descended from common ancestors.

Question 20

Among known plant species, which of these have been the two most commonly occurring phenomena that have led to the origin of new species?

1. allopatric speciation
2. sympatric speciation
3. sexual selection
4. polyploidy

Answer 20

2 & 4

Question 21

The origin of a new plant species by hybridization, coupled with accidents during nuclear division, is an example of

a) autopolyploidy.
b) allopatric speciation.
c) habitat selection.
d) sympatric speciation.

Answer 21

d) sympatric speciation.

Question 22

Dog breeders maintain the purity of breeds by keeping dogs of different breeds apart when they are fertile. This kind of isolation is most similar to which of the following reproductive isolating mechanisms?

a) mechanical isolation
b) hybrid breakdown
c) gametic isolation
d) reduced hybrid fertility
e) habitat isolation

Answer 22

e) habitat isolation

Question 23

Theoretically, the production of sterile mules by interbreeding between female horses (mares) and male donkeys (jacks) should

a) strengthen postzygotic barriers between horses and donkeys.
b) cause convergent evolution.
c) weaken the intrinsic reproductive barriers between horses and donkeys.
d) eventually result in the formation of a single species from the two parental species.

Answer 23

a) strengthen postzygotic barriers between horses and donkeys.

Question 24

Two closely related populations of mice have been separated for many generations by a river. Climatic change causes the river to dry up, thereby bringing the mice populations back into contact in a zone of overlap. Which of the following is not a possible outcome when they meet?

a) They remain separate in the extremes of their ranges but develop a persistent hybrid zone in the area of overlap.
b) They interbreed in the region of overlap, but produce sterile offspring.
c) They no longer attempt to interbreed.
d) They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations.

Answer 24

d) They interbreed in the region of overlap, producing an inferior hybrid. Subsequent interbreeding between inferior hybrids produces progressively superior hybrids over several generations.

Question 25

An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to

a) change the atmosphere from oxidizing to reducing.
b) make it easier to maintain reduced molecules.
c) generate intense lightning storms.
d) cause iron in ocean water and terrestrial rocks to rust (oxidize).
e) prevent the formation of an ozone layer.

Answer 25

d) cause iron in ocean water and terrestrial rocks to rust (oxidize).

Question 26

Which measurement(s) would help determine absolute dates by radiometric means?

a) the accumulation of the daughter isotope
b) the loss of daughter isotopes
c) the loss of parent isotopes
d) Three of the responses above are correct.
e) Two of the responses above are correct.

Answer 26

e) Two of the responses above are correct.

Question 27

Which of the following statements provides the strongest evidence that prokaryotes evolved before eukaryotes?

a) The oldest fossilized cells resemble prokaryotes.
b) Liposomes closely resemble prokaryotic cells.
c) The meteorites that have struck Earth contain fossils only of prokaryotes.
d) Prokaryotic cells lack nuclei.

Answer 27

a) The oldest fossilized cells resemble prokaryotes.

Question 28

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

a) biochemical pathways.
b) morphology.
c) mutations to homologous genes.
d) the pattern of embryological development.
e) habitat and lifestyle choices.

Answer 28

c) mutations to homologous genes.

Question 29

A monophyletic group

a) is the basal taxon.
b) includes species that show convergent evolution.
c) includes the groups that form the nodes on a phylogenetic tree.
d) is an ancestral species and includes some of its descendants.
e) is an ancestral species and includes all of its descendants.

Answer 29

e) is an ancestral species and includes all of its descendants.

Question 30

The largest unit within which gene flow can readily occur is a

a) population.
b) species.
c) genus.
d) hybrid.

Answer 30

b) species.

Question 31

Males of different species of the fruit fly Drosophila that live in the same parts of the Hawaiian Islands have different elaborate courtship rituals. These rituals involve fighting other males and making stylized movements that attract females. What type of reproductive isolation does this represent?

a) habitat isolation
b) temporal isolation
c) behavioural isolation
d) gametic isolation

Answer 31

c) behavioural isolation

Question 32

According to the punctuated equilibria model..?

a) given enough time, most existing species will branch gradually into new species.
b) most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species.
c) most evolution occurs in sympatric populations.
d) speciation is usually due to a single mutation.

Answer 32

b) most new species accumulate their unique features relatively rapidly as they come into existence, then change little for the rest of their duration as a species.

Question 33

Which of the following factors would not contribute to allopatric speciation?

a) The separated population is small, and genetic drift occurs.
b) The isolated population is exposed to different selection pressures than the ancestral population.
c) Different mutations begin to distinguish the gene pools of the separated populations.
d) Gene flow between the two populations is extensive.

Answer 33

d) Gene flow between the two populations is extensive.

Question 34

Fossilized stromatolites

a) formed around deep-sea vents.
b) resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays.
c) provide evidence that plants moved onto land in the company of fungi around 500 million years ago.
d) contain the first undisputed fossils of eukaryotes and date from 2.1 billion years ago.

Answer 34

b) resemble structures formed by bacterial communities that are found today in some warm, shallow, salty bays.

Question 35

The oxygen revolution changed Earth’s environment dramatically. Which of the following took advantage of the presence of free oxygen in the oceans and atmosphere?

a) the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules
b) the persistence of some animal groups in anaerobic habitats
c) the evolution of photosynthetic pigments that protected early algae from the corrosive effects of oxygen
d) the evolution of chloroplasts after early protists incorporated photosynthetic cyanobacteria

Answer 35

a) the evolution of cellular respiration, which used oxygen to help harvest energy from organic molecules

Question 36

Adaptive radiations can be a direct consequence of three of the following four factors. Select the exception.

a) vacant ecological niches
b) genetic drift
c) colonization of an isolated region that contains suitable habitat and few competitor species
d) evolutionary innovation

Answer 36

b) genetic drift

Question 37

Fossil evidence suggests that polar bears, Ursus maritimus, arose from grizzly bears, Ursus arctos. On average, polar bears are slightly larger than grizzly bears in size and weight. The morphological features/adaptations of polar bears make them well suited to survival in a marine environment. Interbreeding and production of fertile offspring between the two species has been recorded in captivity, and more recently in the wild.

The biological species concept emphasized the absence of gene flow. Which alternative species concept(s) is(are) applicable to explaining the hybridization between grizzly and polar bears?

a) the morphological species concept, since it puts emphasis on similarities between the two species
b) the ecological species concept, as it addresses organisms’ adaptations to changing environmental conditions
c) the allopatric species concept, since it emphasizes geographical barriers
d) the morphological and ecological species concepts, as described above
e) the ecological and allopatric species concepts, as described above

Answer 37

d) the morphological and ecological species concepts, as described above

Question 38

Allopatric speciation is most likely to be observed among which species?

a) tigers and wolves
b) pollen of pine trees and grass
c) bats and butterflies
d) mice and snails
e) eagles and gulls

Answer 38

d) mice and snails

Question 39

All animals with eyes or eyespots that have been studied so far share a gene in common. When mutated, the gene Pax-6 causes lack of eyes in fruit flies, tiny eyes in mice, and missing irises (and other eye parts) in humans. The sequence of Pax-6 in humans and mice is identical. There are so few sequence differences with fruit fly Pax-6 that the human/mouse version can cause eye formation in eyeless fruit flies, even though vertebrates and invertebrates last shared a common ancestor more than 500 million years ago.

The appearance of Pax-6 in all animals with eyes can be explained in multiple ways. Based on the information above, which explanation is most likely?

a) The Pax-6 gene was an innovation of an ancestral animal of the early Cambrian period. Animals with eyes or eyespots are descendants of this ancestor.
b) The perfectly designed Pax-6 gene appeared instantaneously in all animals created to have eyes or eyespots.
c) Pax-6 in all of these animals is not homologous; it arose independently in many different animal phyla due to intense selective pressure favouring vision.
d) The Pax-6 gene is really not “one” gene. It is many different genes that, over evolutionary time and due to convergence, have come to have a similar nucleotide sequence and function.

Answer 39

a) The Pax-6 gene was an innovation of an ancestral animal of the early Cambrian period. Animals with eyes or eyespots are descendants of this ancestor.

Question 40

Which of the following statements does not apply to Hox genes?

a) They provide positional information in animal embryos.
b) Changes in how two Hox genes in snakes are expressed results in suppression of limb formation.
c) They are a type of homeotic gene.
d) They alter the timing of reproductive development.

Answer 40

d) They alter the timing of reproductive development.

Question 41

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

a) All variation between individuals is due only to environmental factors.
b) The environment is changing at a relatively slow rate.
c) The population lives in a habitat where there are no competing species present.
d) The population size is large.

Answer 41

a) All variation between individuals is due only to environmental factors.

Question 42

Polyploidy can be best described as

a) an error in mitosis.
b) a form of speciation that commonly occurs in plants and animals.
c) a condition that enhances gene flow.
d) a condition that could lead to speciation as a result of duplication of chromosomes.
e) a condition that requires geographic isolation.

Answer 42

d) a condition that could lead to speciation as a result of duplication of chromosomes.

Question 43

What does the biological species concept use as the primary criterion for determining species boundaries?

a) morphological similarity
b) molecular (DNA, RNA, protein) similarity
c) geographic isolation
d) niche differences
e) gene flow

Answer 43

e) gene flow

Question 44

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

a) None of the organisms depicted by the tree ate the same foods.
b) Some of the organisms depicted by the tree had lived in different habitats.
c) Transitional fossils had not been found.
d) Relationships between DNA sequences among the species did not match relationships between skeletal patterns.
e) The skeletal remains of the organisms depicted by the tree were incomplete (in other words, some bones were missing).

Answer 44

d) Relationships between DNA sequences among the species did not match relationships between skeletal patterns.

Question 45

Two species of frogs belonging to the same genus occasionally mate, but the offspring fail to develop and hatch. What is the mechanism for keeping the two frog species separate?

a) gametic isolation
b) the postzygotic barrier called hybrid inviability
c) the postzygotic barrier called hybrid breakdown
d) the prezygotic barrier called hybrid sterility

Answer 45

b) the postzygotic barrier called hybrid inviability

Question 46

A hybrid zone is properly defined as

a) an area where two closely related species’ ranges overlap.
b) a zone that includes the intermediate portion of a cline.
c) a zone that features a gradual change in species composition where two neighbouring ecosystems border each other.
d) an area where mating occurs between members of two closely related species, producing viable offspring.
e) an area where members of two closely related species intermingle, but experience no gene flow.

Answer 46

d) an area where mating occurs between members of two closely related species, producing viable offspring.

Question 47

Rocky Mountain juniper (Juniperus scopulorum) and one-seeded juniper (J. monosperma) have overlapping ranges. If pollen grains (which contain sperm cells) from one species are unable to germinate and make pollen tubes on female ovules (which contain egg cells) of the other species, then which of these terms is applicable?

a) mechanical isolation
b) reduced hybrid viability
c) hybrid breakdown
d) behavioural isolation

Answer 47

a) mechanical isolation

Question 48

Prezygotic barriers include all of the following, except for

a) habitat isolation.
b) temporal isolation.
c) hybrid breakdown.
d) gametic isolation.
e) mechanical isolation.

Answer 48

c) hybrid breakdown.

Question 49

How many of the following statements concerning the loss of hind limbs during whale evolution are true?
1. It is well documented by a series of transitional fossils.
2. It explains why modern whales have vestigial pelvic girdles.
3. It involved changes in the sequence or expression of Hox genes.
4. It is an example of macroevolution.
5. It, and the loss of limbs by snakes, are examples of similar adaptations to a similar environment.

Answer 49

Four statements are true.

Question 50

What is true of the fossil record of mammalian origins?

a) It shows that mammals and birds evolved from the same kind of dinosaur.
b) It includes transitional forms with progressively specialized teeth.
c) It includes a series that shows the gradual change of scales into fur.
d) It is a good example of punctuated equilibrium.
e) It indicates that mammals and dinosaurs did not overlap in geologic time.

Answer 50

b) It includes transitional forms with progressively specialized teeth.

Question 51

Which pair of structures best represents convergent evolution?

a) the wing of a penguin and the wing of an eagle
b) the tailbone of a human and the tail of a monkey
c) the bones in the forelimb of a horse and wing of a bat
d) the bones in a human arm and flipper of a seal
e) the fusiform shape of a shark and a dolphin

Answer 51

e) the fusiform shape of a shark and a dolphin

Question 52

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

a) eyelessness in the Australian mole and eyelessness in the North American mole
b) owl wing and hornet wing
c) bat wing and bird wing
d) bones in the bat wing and bones in the human forelimb

Answer 52

d) bones in the bat wing and bones in the human forelimb

Question 53

Species that are not closely related and that do not share many anatomical similarities can still be placed together on the same phylogenetic tree by comparing their

a) mitochondrial genomes.
b) homologous genes that are highly conserved.
c) homologous genes that are poorly conserved.
d) plasmids.

Answer 53

b) homologous genes that are highly conserved.

Question 54

Which of the following events would be LEAST likely to trigger an adaptive radiation?

a) colonization of uninhabited islands
b) small habitats with few vacant ecological niches
c) colonization of new habitats
d) the evolution of new innovations, such as jaws, teeth, seeds
e) presence of few competitors and/or predators

Answer 54

b) small habitats with few vacant ecological niches