Part 3

Question 1

Which of the following statements about evolution is true?
a. Evolution only results in the addition of traits to existing organisms.
b. Evolution only results in the loss of traits from existing organisms.
c. Evolution can result in the addition or loss of traits in existing organisms.
d. Evolution has nothing to do with the addition or loss of traits.

Answer 1

c. Evolution can result in the addition or loss of traits in existing organisms.

Question 2

Evolution is
a. not supported by scientific evidence. c. not supported by the fossil record.
b. strongly supported by scientific evidence. d. too obscure to study

Answer 2

b. strongly supported by scientific evidence.

Question 3

Which of the following statements regarding the evolutionary history of an organism is FALSE?
a. Predictions of evolutionary relatedness based on fossil records often agree with predictions
based on continental drift.
b. Predictions of evolutionary relatedness based on fossil evidence often agree with those
based on protein sequences.
c. Predictions of evolutionary relatedness based on DNA usually contradict those based on
anatomical evidence.
d. Predictions based on DNA sequences provide the strongest evidence that two organisms
are related

Answer 3

c. Predictions of evolutionary relatedness based on DNA usually contradict those based on
anatomical evidence.

Question 4

Breeding programs for farm-raised chickens result in a variety of unusual colors and feathers. Is this an
example of evolution?
a. No. Domesticated animals do not undergo evolution.
b. No. Evolution occurs over long periods of time and cannot be observed.
c. Yes. Chickens that are better adapted to the environment will survive and breed.
d. Yes. The change in chicken coloration is a genetic change in the population over time

Answer 4

d. Yes. The change in chicken coloration is a genetic change in the population over time

Question 5

Cultivation of corn over thousands of years has resulted in a modern corncob that looks very different
from the tiny ancestral cob. Does this support the concept of evolution?
a. No. The change in corn was accidental and does not demonstrate the process of evolution.
b. Yes. The change in corn is an example of natural selection and demonstrates the process
of evolution.
c. No. Artificial selection is driven by humans rather than natural selection and does not
demonstrate what occurs in the wild.
d. Yes. Artificial selection demonstrates that evolution can occur, even though the driving
force was humans rather than natural selection.

Answer 5

d. Yes. Artificial selection demonstrates that evolution can occur, even though the driving
force was humans rather than natural selection.

Question 6

Humans simulate the process of natural selection when they use ________ to develop new varieties of
crop plants that better meet the needs of farmers.
a. artificial selection c. habitat changes
b. gene flow d. continental drift

Answer 6

a. artificial selection

Question 7

Natural selection
a. is the principle cause of extinctions.
b. is the principle cause of evolutionary change.
c. occurs only in gametes.
d. cannot occur without genetic drift

Answer 7

b. is the principle cause of evolutionary change.

Question 8

The result of ________ over evolutionary time spans is that alleles that allow organisms to survive and
reproduce at a higher rate than other individuals become more common in the population.
a. natural selection c. homology
b. artificial selection d. gene flow

Answer 8

a. natural selection

Question 9

Natural selection tends to
a. increase the commonality of characteristics that enhance survival and reproduction.
b. decrease the number of individuals in any given population.
c. lead to an increase in genetic drift.
d. decrease the likelihood of adaptation.

Answer 9

a. increase the commonality of characteristics that enhance survival and reproduction.

Question 10

The fossil record
a. proves that all known species of organisms appeared at the same time.
b. contains strong evidence that major new groups of organisms arose from previously
existing organisms.
c. indicates that humans date back as far as the first indications of life.
d. has often been artificially created by evolutionary biologists

Answer 10

b. contains strong evidence that major new groups of organisms arose from previously
existing organisms

Question 11

Bears have thinner bones than whales. Hippopotami have intermediate bone thickness. What hypothesis
does this support?
a. Hippopotami live in dense, murky waterways.
b. Whales and bears both evolved from hippopotami.
c. Hippopotami spend part of their time living in water and part living on land.
d. Hippopotami are an intermediate species in the evolutionary lineage between whales and
bears.

Answer 11

c. Hippopotami spend part of their time living in water and part living on land.
d. Hippo

Question 12

Whales have tiny thighbones embedded in the skin next to their pelvis. This is an example of
a. fossilization. c. a vestigial structure.
b. genetic drift. d. an analogous structure

Answer 12

c. a vestigial structure

Question 13

When comparing certain amino acid sequences in the protein hemoglobin of humans to those of other
animals, scientists found that baboons had seven amino acids that were different than the human protein,
dogs had 10 amino acids that were different than the human protein, gorillas had one amino acid that was
different than the human protein, and lemurs had eight amino acids that were different than the human
protein. Which of these animals is most closely related to humans?
a. baboon c. lemur
b. dog d. gorilla

Answer 13

d. gorilla

Question 14

Whales and Indohyus share a more recent common ancestor than whales and fish. Which of the following
is true?
a. Whales, fish and Indohyus will all have the same amount of genetic similarities.
b. Whales and Indohyus will have more similarities in their DNA than whales and fish.
c. Whales and fish will have more similarities in their DNA than whales and Indohyus.
d. Fish and Indohyus will have more similarities in their DNA than fish and whales

Answer 14

b. Whales and Indohyus will have more similarities in their DNA than whales and fish

Question 15

Pangaea is
a. the process of continental drift.
b. the combined fossil record of ancient species.
c. an ancient, giant continent.
d. the result of natural selection

Answer 15

c. an ancient, giant continent.

Question 16

Fossils of organisms that lived on Pangaea are likely found
a. mainly in Africa. c. mainly in South America.
b. mainly in Eurasia. d. widely dispersed throughout the world

Answer 16

d. widely dispersed throughout the world

Question 17

Two fossils of the same species are found in both Africa and South America. What does this indicate?
a. This organism evolved after the separation of Pangaea.
b. This organism evolved before the separation of Pangaea.
c. The fossil from South America evolved from the organism from Africa.
d. The fossil from Africa evolved from the organism from South America.

Answer 17

b. This organism evolved before the separation of Pangaea.

Question 18

Kangaroos are found only in Australia; these organisms
a. have few adaptive qualities.
b. have a narrow biogeography.
c. evolved few vestigial structures.
d. evolved before the separation of Pangaea

Answer 18

b. have a narrow biogeography.

Question 19

The fossils of organisms that existed when the continents were connected are distributed across ________
continents than the fossils of organisms that evolved after the continents separated.
a. more c. older
b. fewer d. younger

Answer 19

a. more

Question 20

The genus Lycopodium includes plants that evolved before the breakup of Pangaea. The genus
Sequoiadendron (Sequoia trees) evolved after Pangaea split into separate landmasses. Which genus would
you expect to have the widest distribution of living representatives across the modern continents?
a. Lycopodium c. Both should be equally distributed.
b. Sequoiadendron d. Both should be extinct

Answer 20

a. Lycopodium

Question 21

Which of the following embryo will look similar to human embryos for the longest?
a. bird c. fish
b. cat d. reptile

Answer 21

b. cat

Question 22

Why do human embryos develop gill slits?
a. The gill slits become the lungs.
b. The ancestor of humans had gills.
c. This helps the embryo breathe in the womb.
d. This is an unexplained mutation in humans that does not exist in other animals

Answer 22

b. The ancestor of humans had gills.

Question 23

Some whales have teeth as embryos but do not as adults. What is the most likely explanation of this
phenomenon?
a. Whales are in the process of evolving teeth.
b. Whale teeth appear as the result of a frequently occurring mutation.
c. Whales evolved from organisms that have teeth.
d. The allele for teeth is unusually common in some whale populations

Answer 23

c. Whales evolved from organisms that have teeth.

Question 24

Tails are found
a. in all embryos.
b. only in adults and begin forming late in development.
c. only in embryos of organisms that will have a tail as adults.
d. in embryos of a wide variety of organisms, some of which have a tail as adults and others
do not.

Answer 24

d. in embryos of a wide variety of organisms, some of which have a tail as adults and others
do not.

Question 25

Dolphin embryos develop hind limb buds, but these buds disappear after a short time. What is one
mechanism to explain how this change occurs in the embryo?
a. The hind limbs are not used and atrophy.
b. The dolphin does not have the gene for the production of hind limbs.
c. The hind limbs are not adaptive and dolphins with hind limbs do not survive as well.
d. Genes that control the development of the embryo turn off the development of the hind
limb.

Answer 25

d. Genes that control the development of the embryo turn off the development of the hind
limb.

Question 26

Human and fish embryos share a number of features. Why is this?
a. Humans and fish share a common ancestor.
b. Embryos of all organisms, plant and animal, look alike.
c. Mutations in human and fish embryos have caused them to look alike.
d. Humans and fish have exactly the same genes, but as they develop, different genes are
turned on in fish than in humans.

Answer 26

a. Humans and fish share a common ancestor.

Question 27

Evolution can be described as
a. predesigned change in the genetic characteristics of a population of organisms over time.
b. sudden shifts in the genetic characteristics of an individual in a population.
c. a change in the genetic characteristics of a population of organisms over time.
d. isolation of populations due to geologic forces

Answer 27

c. a change in the genetic characteristics of a population of organisms over time.

Question 28

Evolutionary changes occur when ________ acts upon populations containing individuals with genetic
differences.
a. continental drift c. weather
b. natural selection d. mutation

Answer 28

b. natural selection

Question 29

An example of evolution that has been readily observed is
a. a chameleon changing colors as it moves from a leaf of one color to a leaf of another
color.
b. increased resistance of bacteria to an antibiotic that is used to kill them.
c. chimpanzees learning sign language.
d. humans teaching dogs to obey certain commands.

Answer 29

b. increased resistance of bacteria to an antibiotic that is used to kill them.

Question 30

What is the total number of alleles present for any given gene in a population of 100 individuals?
a. 50 c. 200
b. 100 d. 400

Answer 30

c. 200

Question 31

A gene has two alleles, D and d. The frequency of the D allele is 0.2. What is the frequency of the d
allele?
a. 0.2 c. 0.64
b. 0.4 d. 0.8

Answer 31

d. 0.8

Question 32

If a given population has 30 RR individuals, 10 Rr individuals, and 10 rr individuals, what is the allele
frequency of R?
a. 0.1 c. 0.5
b. 0.3 d. 0.7

Answer 32

d. 0.7

Question 33

Jean-Baptiste Lamark proposed that populations evolve when traits acquired during the lifetime of a
parent are passed down to offspring. What is wrong with this proposal?
a. Only changes in the DNA sequence of an organism can be inherited. Traits acquired
throughout life generally do not involve DNA.
b. The environment chooses which traits are necessary for survival rather than the individual.
c. Changes in a species occur at the individual level rather than at the population level.
d. The inheritance of acquired traits would not lead to speciation because it would cause all
of the individuals in a population to become more similar

Answer 33

a. Only changes in the DNA sequence of an organism can be inherited. Traits acquired
throughout life generally do not involve DNA.

Question 34

New alleles arise by
a. nonrandom mating. c. genetic drift.
b. allele frequency. d. mutation

Answer 34

d. mutation

Question 35

Which of the following is true with regard to mutations?
a. Mutations occur in response to environmental pressures.
b. Mutations are more common in slowly growing organisms.
c. Mutations appear without regard to environmental pressures.
d. Several mutations must occur at one time for a new phenotype to appear

Answer 35

c. Mutations appear without regard to environmental pressures.

Question 36

Insecticides are used to kill insects. However, insecticide resistant insects are being found. What is the
mechanism for this new insect trait?
a. An insect with a random mutation is not killed by the insecticide and reproduces.
b. Exposing insects to insecticides leads to mutations, which make the insects resistant.
c. Human interference with natural processes leads to genetic drift, which results in resistant
insects.
d. Insecticides kill all the insects in a population, and a different species of resistant insects
colonizes the available resources.

Answer 36

a. An insect with a random mutation is not killed by the insecticide and reproduces.

Question 37

The color of a certain species of beetle is determined by a single gene. Two beetles homozygous for green
coloration (meaning they have two copies of the green allele) produce a single offspring with brown
coloration. Brown color appeared in this offspring as a result of
a. bottleneck. c. genetic drift.
b. gene flow. d. mutation

Answer 37

d. mutation

Question 38

A student with Strep throat (caused by a strain of bacterium) is given a prescription for an antibiotic and
is told to take the drug for two weeks. After a week, the student feels better and stops taking the drug.
Two months later, the student again shows symptoms of Strep throat and decides to finish the leftover
antibiotic rather than going to the doctor again. Two months later, the student develops Strep throat for a
third time and returns to the doctor. This time, the antibiotic does not work. The doctor runs a test and
discovers that the bacterial strain the student is carrying is antibiotic resistant. What most likely
happened?
a. Because the use of antibiotics lowers the effectiveness of the immune system, the student
continually reinfected himself with the bacteria. The third time, the student happened to be
reinfected with a resistant strain.
b. When the student stopped taking the drug, a small number of bacteria—those that were
more drug resistant—still survived in his body. Those bacteria repopulated his throat and
over time, drug-resistant alleles became more common.
c. The student must have eaten produce that had been genetically engineered with antibiotic-
resistant genes. When he consumed them, the bacteria in the student’s throat picked up
these genes through horizontal gene transfer.
d. The antibiotic caused mutations in the bacterium. The more exposure to the antibiotic, the
more mutations

Answer 38

b. When the student stopped taking the drug, a small number of bacteria—those that were
more drug resistant—still survived in his body. Those bacteria repopulated his throat and
over time, drug-resistant alleles became more common.

Question 39

Which of the following is NOT a mode of natural selection?
a. directional selection c. dormant selection
b. disruptive selection d. stabilizing selection

Answer 39

c. dormant selection

Question 40

Disruptive selection operates whenever
a. natural selection is disrupted by genetic drift.
b. there is a balanced gene pool.
c. only the smallest individuals survive.
d. both extremes of the phenotype are more successful.

Answer 40

d. both extremes of the phenotype are more successful.

Question 41

In natural selection, ________ that increase survival and reproductive success become more common in a
population.
a. genotypes c. bottlenecks
b. allele frequencies d. phenotypes

Answer 41

d. phenotypes

Question 42

Several related bird species live in a desert. One species is much smaller than the other species. This
species nests in holes in cacti. Because the bird is so small, it can easily squeeze between the spines of the
cactus and create a well-protected nest. This is an example of
a. genetic drift. c. natural selection.
b. mutation. d. gene flow.

Answer 42

c. natural selection

Question 43

Two different species may have similar features because of
a. genetic drift. c. a bottleneck.
b. the founder effect. d. descent from a common ancestor

Answer 43

d. descent from a common ancestor

Question 44

Convergent evolution occurs when natural selection causes distantly related organisms to
a. evolve into the same species despite the fact that they are members of separate
populations.
b. merge into one continuous population because of reversals in continental drift.
c. evolve both analogous and homologous characteristics.
d. evolve similar structures in response to similar environmental challenges

Answer 44

d. evolve similar structures in response to similar environmental challenges

Question 45

Two unrelated species evolving to look more similar due to environmental pressures is called
a. gene flow. c. convergent evolution.
b. genetic drift. d. divergent evolution.

Answer 45

c. convergent evolution.

Question 46

Convergent evolution produces
a. genetic drift. c. homologous characteristics.
b. lines of common descent. d. analogous characteristics

Answer 46

d. analogous characteristics

Question 47

Both insects and humans evolved jointed legs to allow locomotion on land. These structures are
considered analogous because insects and humans
a. stopped evolving at different times in Earth’s history.
b. evolved from different ancestors.
c. cannot breed.
d. faced different environmental challenges during evolutionary time

Answer 47

b. evolved from different ancestors.

Question 48

Some finches on the Galápagos Islands eat insects, an unusual food for finches to eat. These finches
a. evolved from a lineage of birds other than finches that ate insects.
b. learned their habits from local birds.
c. switched to insects because they tasted better than their usual food.
d. fill roles that birds other than finches would fill in other places

Answer 48

d. fill roles that birds other than finches would fill in other places

Question 49

The wings of a bird and the wings of a bat both form from the front appendages (arms). The bird wing is
covered by feathers, and the bat wing consists of a thin layer of skin stretched between the “finger” bones.
Are the wings of the bird and bat homologous or analogous?
a. homologous, because they evolved from the same body part
b. analogous, because birds’ flight requires feathers and bats use skin; both are wings, but
they evolved differently
c. both; they are homologous because they both evolved from a front appendage, but
analogous because they evolved differently
d. neither, because birds and bats do not share a recent common ancestor

Answer 49

c. both; they are homologous because they both evolved from a front appendage, but
analogous because they evolved differently

Question 50

Both mammals and octopi have evolved similar eye structures. This is an example of
a. convergent evolution. c. disruptive selection.
b. divergent evolution. d. directional selection

Answer 50

a. convergent evolution

Question 51

Which of the following is NOT likely to be a cause of rapid evolution in a population?
a. a changing environment
b. an organism that exhibits a rapid rate of mutation
c. an organism that reproduces very slowly
d. the immigration of individuals carrying a new allele that significantly increases
reproductive success

Answer 51

c. an organism that reproduces very slowly

Question 52

Which of the following is NOT a cause of evolution?
a. mutation c. stable environmental conditions
b. gene flow d. sexual selection

Answer 52

c. stable environmental conditions

Question 53

For a population to evolve, there must be genetic differences between organisms in that population. These
differences arise by
a. mutation. c. natural selection.
b. a change in an organism’s behavior. d. common descent

Answer 53

a. mutation

Question 54

Genetic variation is based on
a. the inheritance of alleles accumulated during the lifetime of an individual.
b. differences in genotypes between the individuals in a population.
c. the accumulation of mutations in somatic cells (as opposed to gametes).
d. the formation of new combinations of alleles during asexual reproduction.

Answer 54

b. differences in genotypes between the individuals in a population.

Question 55

UV light causes mutations within skin cells. Is UV light a major driving force in the evolution of animals?
a. Yes. UV light is always present outside and can produce both favorable and harmful
mutations in skin cells. Only the favorable mutations will be passed on to the next
generation.
b. Yes. A mutation in the skin cell will result in an organism that is better protected from the
sun. This individual will be more likely to survive and pass on this mutation to the next
generation.
c. No. Only mutations in gametes will be passed on to the next generation. Only mutations
that are passed on to offspring contribute to evolution.
d. No. Only mutations that have a favorable adaptive quality will be passed on to the next
generation. UV light produces only harmful mutations

Answer 55

c. No. Only mutations in gametes will be passed on to the next generation. Only mutations
that are passed on to offspring contribute to evolution.

Question 56

A mutation in a gene produces the identical protein to the original gene and therefore, an identical trait.
Will evolution act upon this mutation?
a. No, because evolution acts upon phenotypes.
b. Yes, because evolution acts upon phenotypes.
c. Yes, because mutations do contribute to evolution
d. No, because mutations do not contribute to evolution

Answer 56

a. No, because evolution acts upon phenotypes

Question 57

Gene flow occurs
a. as a result of genetic drift.
b. when an individual migrates between two otherwise isolated populations of a species.
c. as a result of mutations in one population but not in another.
d. when individuals within a population interbreed

Answer 57

b. when an individual migrates between two otherwise isolated populations of a species.

Question 58

During gene flow,
a. chance events alter the gene pool of a population.
b. new individuals contribute their alleles to the gene pool of a population.
c. alleles that make an individual more successful move from one population to another.
d. crossing-over creates new combinations of alleles during gamete formation.

Answer 58

b. new individuals contribute their alleles to the gene pool of a population

Question 59

While on a camping trip, you collect a white tadpole from a pond and take it home. The tadpole develops
into a white bullfrog. When the frog gets too big, you release it into a local pond. The next year, several
white bullfrogs are observed in the pond. This is an example of
a. genetic drift. c. gene flow.
b. natural selection. d. sexual selection.

Answer 59

c. gene flow.

Question 60

Gene flow between two populations
a. makes the genetic composition of the two populations more similar.
b. eliminates harmful alleles.
c. magnifies the effects of genetic drift.
d. creates genetic differences between the populations.

Answer 60

a. makes the genetic composition of the two populations more similar.

Question 61

Which of the following is NOT a step in the evolutionary process?
a. Mutation results in the formation of new alleles, and sexual reproduction results in new
combinations of alleles.
b. New genes are introduced into a population when members of that population mate with
members of other species and produce offspring.
c. Genetic variation is inherited by the next generation of a population.
d. Genetic drift, gene flow, and/or natural selection cause allele frequencies to change over
time

Answer 61

b. New genes are introduced into a population when members of that population mate with
members of other species and produce offspring.

Question 62

Which of the following is an example of gene flow?
a. Pollen from a population A plant lands on the same plant (mating with itself).
b. Pollen from a population A plant lands on another population A plant.
c. Pollen from a population A plant lands on a population B plant.
d. Pollen from a population B plant lands on a population B plant.

Answer 62

c. Pollen from a population A plant lands on a population B plant.

Question 63

How do natural selection and sexual selection differ?
a. Natural selection increases the frequency of alleles that contribute to survival, but sexual
selection may increase the frequency of alleles that are not beneficial to survival.
b. Natural selection contributes to genetic drift, but sexual selection contributes to gene flow.
c. Natural selection is more random than sexual selection.
d. Natural selection increases the fitness of an allele, but sexual selection increases the
dimorphism of an allele.

Answer 63

a. Natural selection increases the frequency of alleles that contribute to survival, but sexual
selection may increase the frequency of alleles that are not beneficial to survival.

Question 64

Sexual selection can result in an increased frequency of alleles, which
a. may be harmful to the individual’s survival but is always beneficial to its reproductive
rate.
b. are always beneficial to the individual’s survival but may be harmful to its reproductive
rate.
c. are always beneficial to both the individual’s survival and reproductive rate.
d. may be harmful to both the individual’s survival and reproductive rate

Answer 64

a. may be harmful to the individual’s survival but is always beneficial to its reproductive
rate.

Question 65

What is genetic drift?
a. gene mutation within, or between, populations
b. chance evolutionary change occurring in small populations
c. natural selection acting on large populations
d. shifts in allelic frequencies due to mutation

Answer 65

b. chance evolutionary change occurring in small populations

Question 66

A population of 8,250 mice occupies the sand dunes in a coastal area. A severe hurricane washes out
several miles of sand dunes. As a result, only 50 mice remain. The population has experienced
a. horizontal gene transfer. c. founder effect.
b. gene flow. d. a bottleneck.

Answer 66

d. a bottleneck.

Question 67

Which of the following statements concerning evolution is FALSE?
a. Natural selection requires variation in the population.
b. An individual that is better adapted than others in a population will always be more
reproductively successful.
c. Genetic drift causes little evolutionary change in large populations.
d. Evolution involves a change of frequency of alleles in the gene pool

Answer 67

b. An individual that is better adapted than others in a population will always be more
reproductively successful.

Question 68

Compared to a large mainland population, genetic drift in a small island population is
a. less important because there is less variation with which to work.
b. less important because only a few individuals do all the breeding.
c. more important because of a smaller gene pool.
d. more important because of the absence of competition

Answer 68

c. more important because of a smaller gene pool.

Question 69

A used car is shipped from Australia to the United States. Stowed away in the trunk of the car is a piece
of wood infected with Australian termites. Once in the United States, the buyer of the car finds the rotting
wood and dumps it on the side of the road. The termites survive and establish a colony on the side of
the road but do not mate with local termite populations. This is an example of
a. genetic drift. c. natural selection.
b. mutation. d. gene flow

Answer 69

a. genetic drift

Question 70

A fisherman catches one trout from each of two ponds. Pond A contains 100 trout and pond B contains
1,000 trout. Which population is more affected by the fisherman?
a. Pond A; the fisherman has a greater likelihood of completely removing alleles from the
gene pool by taking a fish from the smaller population.
b. Pond A; fewer fish are able to move into a small pond and find mates.
c. Pond B; the fisherman is more likely to catch a fish that is undergoing evolution in a
bigger population.
d. Pond B; the process of evolution occurs more slowly in large populations and removing a
fish speeds up the process

Answer 70

a. Pond A; the fisherman has a greater likelihood of completely removing alleles from the
gene pool by taking a fish from the smaller population.

Question 71

Although millions of prairie chickens once occupied Illinois, in 1993 only 50 remained. Starting in 1992,
scientists moved almost 300 prairie chickens from large populations in other states to Illinois to ________
Illinois prairie chicken populations.
a. prevent the development of nonheritable mutations in
b. introduce genetic variation back into
c. induce stabilizing selection in
d. cause genetic drift in

Answer 71

b. introduce genetic variation back into

Question 72

The only mechanism of evolutionary change that is not influenced by chance events is _______

Answer 72

natural selection

Question 73

A scientist is studying beak length in a species of hummingbird. The scientist establishes a population of
birds with beaks ranging from very small to very long and allows the population to breed for 10 years. At
the end of the experiment, she finds that the majority of birds in the population have very long beaks. This
is an example of the ________ selection pattern of natural selection

Answer 73

directional

Question 74

The result of convergent evolution is ________ traits.

Answer 74

analogous

Question 75

The original source of genetic variation within a population is ________.

Answer 75

mutation

Question 76

Two populations of geese live near each other. As time passes, the populations are becoming more
genetically alike. This is probably due to ________.

Answer 76

gene flow

Question 77

A chance evolutionary change occurring in small populations is referred to as ________.

Answer 77

genetic drift

Question 78

Adaptive evolution allows species to
a. reduce mutation rate. c. adjust to environmental changes.
b. decrease genetic variation. d. hybridize

Answer 78

c. adjust to environmental changes.

Question 79

Adaptive evolution
a. is large-scale movement of a single species over a new geographic area.
b. occurs when a more adapted species causes the extinction of a less adapted one.
c. is the process by which natural selection improves the match between an organism and its
environment over time.
d. is an increase in the adaptiveness of many species that have already evolved

Answer 79

c. is the process by which natural selection improves the match between an organism and its
environment over time.

Question 80

When a brightly colored guppy population is placed in an area containing many predators, the population
changes in only a few generations to one containing only guppies with drab, dull colors that blend into
their environment. This is an example of how natural selection can
a. force new color mutations to occur.
b. convert a dominant allele into a recessive allele.
c. improve the match between guppies and their environment.
d. change the color preferences of female guppies

Answer 80

c. improve the match between guppies and their environment.

Question 81

A lizard is attacked by a bird. The lizard escapes and survives without his hind legs. Fortunately for this
lizard, the loss of his hind limbs allows him to live within a smaller crevice than other lizards of the same
species so he experiences less competition. Which of the following is true for this lizard?
a. The loss of his legs provided an advantage within his environment.
b. The loss of his hind legs would be considered an adaptive trait.
c. A lack of hind limbs should become more common in this population.
d. This lizard will be unable to reproduce.

Answer 81

a. The loss of his legs provided an advantage within his environment

Question 82

The faster a cheetah can run, the more likely it is to capture its prey. Cheetahs with longer legs are able to
run faster than those with shorter legs. Although the existing cheetah population shows a variety of leg
lengths, cheetah legs are not continuing to increase in length from one generation to the next. Which of
the following is a possible explanation?
a. The genes that are involved in cheetah leg length do not undergo mutation.
b. Cheetahs with long legs are reproductively isolated from cheetahs with short legs.
c. Natural selection does not act on traits involved in predation.
d. Longer cheetah leg bones are more likely to break.

Answer 82

d. Longer cheetah leg bones are more likely to break.

Question 83

Every year, environmental signals in Africa cause flycatchers to return to the Netherlands to breed. When
they arrive, they depend on freshly hatched caterpillars for food. Global climate change has caused the
caterpillars to hatch earlier in the Netherlands, but the environmental cues in Africa remain the same.
Now, when the flycatchers return to the Netherlands the caterpillars are no longer available as a food
source. Which of the following is most likely to happen to this species of flycatcher?
a. Flycatchers may learn that caterpillars are hatching earlier and will begin flying to the
Netherlands earlier.
b. Flycatchers will adapt to environmental change if alleles that aid flycatchers in utilizing
other food sources (besides caterpillars) are present.
c. Flycatchers will not adapt to environmental change because bird species are unable to
utilize new food sources.
d. Flycatchers will remain in the Netherlands instead of returning to Africa.

Answer 83

b. Flycatchers will adapt to environmental change if alleles that aid flycatchers in utilizing
other food sources (besides caterpillars) are present.

Question 84

Which of the following examples does NOT illustrate a difference in fitness that would lead to evolution
by natural selection?
a. Male peacocks with larger, more colorful tails are more frequently chosen as mates.
b. Moths with coloration that allows them to blend in with the bark of spruce trees are more
difficult for predators to find.
c. Wolves who are more successful hunting in packs find mates more frequently.
d. A female panda living in a zoo in China is impregnated more frequently than a female
panda living in a zoo in the United States.

Answer 84

d. A female panda living in a zoo in China is impregnated more frequently than a female
panda living in a zoo in the United States.

Question 85

Some species of orchids attract wasps to assist them in reproduction by producing flowers that look like
female wasps. The flowers fool male wasps into attempting to mate with them. As a result, the wasp is
covered with pollen that it takes with it to the next flower it attempts to mate with. This example shows
adaptive evolution by
a. the orchids. c. all flowering plants.
b. the wasps. d. ancestral wasps.

Answer 85

a. the orchids

Question 86

Bacteria reproduce asexually, so scientists classify them based on
a. the morphological species concept.
b. reproductive isolation.
c. the biological species concept.
d. the idea that they are all strains of the same species.

Answer 86

a. the morphological species concept.

Question 87

Using reproductive isolation as a method of defining a species is NOT useful for
a. species whose ranges overlap.
c. organisms known only from fossils.
b. species that cannot produce hybrids.
d. organisms that reproduce sexually

Answer 87

c. organisms known only from fossils.

Question 88

The fossils of two adult birds are found in a nest containing several fossilized eggs. Physically, the bird
fossils look very different. What are scientists most likely to use to classify these species?
a. the biological species concept c. the morphological species concept
b. the DNA-based species concept d. the evidence of reproduction concept

Answer 88

c. the morphological species concept

Question 89

The red-breasted nuthatch and the white-breasted nuthatch are similar in appearance and, in many regions
of the United States, their ranges overlap. The two organisms do not interbreed. Based on this
information, red-breasted and white-breasted nuthatches are
a. different species. c. hybrids.
b. different populations of the same species. d. polyploids

Answer 89

a. different species

Question 90

Individuals of the same species generally
a. experience prezygotic barriers to reproduction.
b. do not interbreed extensively.
c. share many common physical and behavioral characteristics.
d. vary only very slightly in appearance.

Answer 90

c. share many common physical and behavioral characteristics.

Question 91

Which of the following correctly indicates a relationship between the morphological species concept and
the biological species concept?
a. Organisms that reproduce asexually cannot be defined as a species based on morphology.
b. Organisms capable of interbreeding always have the same physical traits.
c. Organisms capable of interbreeding might have different physical traits.
d. The morphological and biological species concepts are always in agreement

Answer 91

c. Organisms capable of interbreeding might have different physical traits.

Question 92

Which of the following must occur for one species to split into two or more species?
a. The species must move into a new habitat.
b. DNA sequences of genes must accumulate differences.
c. Morphological changes must be obvious within the population.
d. One species must undergo geographic isolation.

Answer 92

b. DNA sequences of genes must accumulate differences.

Question 93

Some freshwater snail eggs are accidentally introduced into a new habitat that is geographically isolated
from the original population. Which of the following must occur before these snails are described as two
separate species?
a. gene flow c. adaptation
b. sympatric speciation
d. genetic divergence

Answer 93

d. genetic divergence

Question 94

For two populations to accumulate enough genetic differences to cause speciation, the factors that
promote these differences
a. must operate in populations that are not physically separated.
b. must have a greater effect than does the amount of ongoing gene flow.
c. need to be combined with the forces of genetic drift.
d. should include polyploidy

Answer 94

b. must have a greater effect than does the amount of ongoing gene flow.

Question 95

Geographic isolation limits the ________ between populations of a species.
a. genetic differences c. directional selection
b. adaptation d. gene flow

Answer 95

d. gene flow

Question 96

A large population of animals is split in two by a physical barrier. Over time, the genetic makeup of the
two resulting populations becomes more and more different until each population becomes a separate
species. This is an example of
a. sympatric speciation. c. genetic drift.
b. allopatric speciation. d. natural selection

Answer 96

b. allopatric speciation

Question 97

For which of the following would a mountain range most likely represent a geographic barrier that would
block gene flow?
a. birds c. mice
b. deer d. butterflies

Answer 97

. mice

Question 98

Which of the following would NOT be expected after a population undergoes geographic isolation?
a. a decrease in gene flow c. allopatric speciation
b. an increase in gene flow
d. formation of adaptive traits

Answer 98

b. an increase in gene flow

Question 99

Which of the following does NOT provide an example of geographic isolation?
a. Two populations live in two valleys on opposite sides of a mountain range.
b. Two populations live on different mountains with a valley between them.
c. Two populations live on opposite sides of a river.
d. Two populations live in different parts of a small lake

Answer 99

d. Two populations live in different parts of a small lake

Question 100

Which of the following statements accurately distinguishes tissues from organs?
a. Organs consist of cells, whereas tissues do not.
b. Organs are limited to one location in the human body, whereas most tissues move
throughout the body.
c. Each organ performs multiple functions, whereas a designated tissue performs only one
function.
d. Organs consist of multiple tissue types, whereas tissues consist of one or more cell types

Answer 100

d. Organs consist of multiple tissue types, whereas tissues consist of one or more cell types

Question 101

Which of the following is a type of epithelial tissue?
a. skin c. bone
b. tendons d. neurons

Answer 101

a. skin

Question 102

For homework, your instructor asks you to write a paragraph discussing how the mouth, stomach, and
small intestines work together to process food items and provide nutrients to the body. Which level of
biological organization are you studying?
a. tissues c. cells
b. organ systems d. organs

Answer 102

b. organ systems

Question 103

Which of the following is a collection of organs?
a. bone, tendons, and fat
b. reproductive, immune, and integumentary
c. heart, lungs, and liver
d. neurons, smooth muscle, and skin

Answer 103

c. heart, lungs, and liver

Question 104

Insulin is a protein hormone that helps cells use glucose. In type 1 diabetes, insulin-making cells in the
pancreas are attacked and destroyed. This is an example of
a. the digestive, circulatory, and excretory systems affecting one another.
b. the importance of only one system being needed to perform a function.
c. the importance of the excretory system in removing wastes and other toxins from the
body.
d. the endocrine, digestive, circulatory, and immune systems affecting one another.

Answer 104

d. the endocrine, digestive, circulatory, and immune systems affecting one another.

Question 105

After about an hour of basking in the sun, the body temperature of the marine iguana reaches 37°C, and
the animal dives into the water to feed. In the water, its body temperature rapidly drops, and the iguana
must return to the rocks to warm up. This process is an example of
a. tissue shock. c. set point control.
b. negative feedback. d. positive feedback.

Answer 105

b. negative feedback

Question 106

Which of the following statements about negative feedback is true?
a. Negative feedback stops a process before it reaches its set point.
b. Negative feedback determines what the set point of a process should be.
c. Negative feedback slows down or shuts off a process when a set point is reached.
d. Negative feedback prevents positive feedback.

Answer 106

c. Negative feedback slows down or shuts off a process when a set point is reached.

Question 107

Some species of fish that live in the cold waters of the Arctic Ocean have evolved an “antifreeze” protein.
Why might this protein be important to homeostasis?
a. The protein might be involved in transporting water into fish cells during cold weather.
The more water in the cell, the smaller the chance that ice crystals will form inside it.
b. The protein might prevent ice crystals from forming inside fish cells, which would prevent
damage to the plasma membrane when temperatures are low.
c. The protein might be involved in removing solutes from fish cells during cold weather.
With fewer solutes in the cell, essential chemical reactions are more likely to occur.
d. The protein might allow this species of fish to survive global warming by enabling the fish
to carry out chemical reactions that would normally be prevented by warm temperatures.

Answer 107

b. The protein might prevent ice crystals from forming inside fish cells, which would prevent
damage to the plasma membrane when temperatures are low.

Question 108

During blood clotting, a broken blood vessel triggers a cascade of factors that collectively reduce blood
loss. In this example, the clotting factors are functioning as part of
a. thermoregulation. c. osmoregulation.
b. a negative feedback loop.
d. a positive feedback loop.

Answer 108

d. a positive feedback loop.

Question 109

How do living systems “know” the appropriate temperature or water content within that system?
a. Living systems depend on signals from the environment to regulate these conditions.
b. Organisms have a genetically predetermined set point that must be internally maintained.
c. Living systems monitor positive feedback mechanisms and shut off negative feedback
loops to regulate these processes.
d. Actually, most living systems do not regulate temperature or water content, so these
features typically fluctuate greatly.

Answer 109

b. Organisms have a genetically predetermined set point that must be internally maintained.

Question 110

Which of the following statements accurately describes similarities between asexual and sexual
reproduction in animals?
a. Both processes increase genetic variation in offspring.
b. Both forms of reproduction produce offspring that have double the amount of genetic
information of the parent(s).
c. Both asexual reproduction and sexual reproduction rely on parental chromosomes to mix
in new ways.
d. Both processes generate offspring that carry parental genes.

Answer 110

d. Both processes generate offspring that carry parental genes.

Question 111

Which of the following terms describes how the male sperm and the female egg typically fuse in animals?
a. internal fertilization
c. spermatogenesis
b. hormonal contraception
d. hermaphroditism

Answer 111

a. internal fertilization

Question 112

Which of the following would be found in the oviduct immediately after fertilization?
a. an embryo c. a zygote
b. an ovum d. a spermatocyte

Answer 112

c. a zygote

Question 113

Which of the following methods of reproduction is NOT used by animals?
a. sexual reproduction involving sperm and eggs
b. asexual reproduction involving only one animal
c. asexual reproduction involving sperm and eggs
d. a piece of an animal breaking off and growing into a new individua

Answer 113

c. asexual reproduction involving sperm and eggs

Question 114

Which of the following statements about hermaphrodites is true?
a. They can mate with every individual of the same species that they encounter.
b. They can generally fertilize their own eggs.
c. They have either testes or ovaries.
d. Most animals reproduce using hermaphroditic reproduction

Answer 114

a. They can mate with every individual of the same species that they encounter

Question 115

Some organisms switch from male to female, or vice versa. The most likely reason for the change is the
a. loss of reproductive ability.
b. loss of chromosomes from one year to the next.
c. ability to reproduce asexually versus sexually.
d. availability of environmental resources.

Answer 115

d. availability of environmental resources.

Question 116

Which of the following statements about sexual reproduction in animals is true?
a. Only one parent contributes genes to the offspring.
b. Both parents contribute genes to the offspring.
c. The offspring are identical to their parents.
d. Only one parent is needed to produce offspring

Answer 116

b. Both parents contribute genes to the offspring

Question 117

Which of the following statements distinguishes gamete formation in human males from gamete
formation in human females?
a. Human males have a shorter reproductive lifespan than human females.
b. Human males make sperm throughout their lives, beginning at puberty, whereas human
females are born with all the eggs that may be fertilized.
c. Human males produce gametes in the gonads, whereas human females produce eggs in the
gut.
d. Human males make two polar bodies during spermatogenesis, whereas human females do
not.

Answer 117

b. Human males make sperm throughout their lives, beginning at puberty, whereas human
females are born with all the eggs that may be fertilized.

Question 118

The number of chromosomes in secondary spermatocytes is fewer than in primary spermatocytes because
a. sister chromatids are separated during meiosis II.
b. sister chromatids are separated during meiosis I.
c. homologous pairs are separated during meiosis II.
d. homologous pairs are separated during meiosis I.

Answer 118

d. homologous pairs are separated during meiosis I.

Question 119

Mature female eggs develop under the control of hormones within the
a. cervix. c. uterus.
b. ovaries. d. oviduct

Answer 119

b. ovaries.

Question 120

Which of the following is a product of the first round of meiosis in males?
a. primary oocyte c. first polar body
b. sperm Which of the following is a product of the first round of meiosis in males?
a. primary oocyte c. first polar body
b. sperm d. secondary spermatocytes

Answer 120

d. secondary spermatocytes

Question 121

A human female has a diploid chromosome number of 46 (2n = 46). Based on this information, which of
the following cells is NOT properly matched with its chromosome number?
a. diploid precursor cell: 46 chromosomes
c. secondary oocyte: 46 chromosomes
b. egg: 23 chromosomes
d. first polar body: 23 chromosome

Answer 121

c. secondary oocyte: 46 chromosomes

Question 122

Which of the following sequences places spermatogenesis in the correct order from start to finish?
a. sperm, primary spermatocyte, secondary spermatocytes, diploid precursor cell
b. diploid precursor cell, secondary spermatocytes, primary spermatocyte, sperm
c. primary spermatocyte, secondary spermatocytes, diploid precursor cell, sperm
d. diploid precursor cell, primary spermatocyte, secondary spermatocytes, sperm

Answer 122

d. diploid precursor cell, primary spermatocyte, secondary spermatocytes, sperm

Question 123

Carbohydrates and fats are both
a. digested and absorbed in the human stomach.
b. sources of amino acids.
c. used as energy sources.
d. indigestible unless they are consumed together

Answer 123

c. used as energy sources.

Question 124

Which of the following statements about the amino acids that are required by adult humans is true?
a. The human body produces 20 amino acids.
b. There are eight amino acids used as building blocks for human proteins.
c. Amino acids are the building blocks of carbohydrates.
d. Amino acids are the building blocks of proteins.

Answer 124

d. Amino acids are the building blocks of proteins.

Question 125

Which of the following nutrients have the lowest energy content per gram?
a. fats c. proteins
b. vitamins d. carbohydrates

Answer 125

b. vitamins

Question 126

If you were a bird about to embark on a long migratory journey, which of the following nutrients would
you want to have stored in large quantities?
a. sugars c. vitamins
b. proteins d. fats

Answer 126

d. fats

Question 127

A genetic mutation has altered a signaling molecule found embedded within cell membranes. This
signaling molecule is most likely a
a. protein. c. fat.
b. carbohydrate. d. dietary fiber

Answer 127

a. protein.

Question 128

The most likely potential problem faced by a person who is following a low-protein diet is the failure to
a. take in the carbon, hydrogen, and oxygen required for life.
b. take in enough essential amino acids.
c. take in enough calories to survive.
d. produce vitamins and minerals required by living organisms.

Answer 128

b. take in enough essential amino acids.

Question 129

As an experiment, a person who wishes to avoid getting ill during the winter significantly boosts his or
her vitamin intake by taking multiple vitamin supplements. This action could
a. help the person live decades longer.
b. be dangerous, because the human body needs vitamins only in small amounts.
c. help the person look decades younger.
d. reduce the person’s fiber intake

Answer 129

b. be dangerous, because the human body needs vitamins only in small amounts

Question 130

Which of the following organs plays a role in producing vitamin D?
a. the skin c. the stomach
b. the small intestine d. the large intestine

Answer 130

a. the skin

Question 131

Babies may receive an injection of vitamin K at birth. Which of the following is the most likely reason
why an injection of vitamin K would be given?
a. Vitamin K is required for calcium absorption, and babies need to build strong bones.
b. Vitamin K is required to prevent bleeding, and babies are born with low levels of this
vitamin.
c. Vitamin K is required for the formation of visual pigments in the eyes, and babies use their
eyes more often than their other senses.
d. Vitamin K is required to build cell membranes, and babies are growing rapidly

Answer 131

b. Vitamin K is required to prevent bleeding, and babies are born with low levels of this
vitamin.

Question 132

Which of the following vitamins is NOT associated with building or maintaining bones and teeth?
a. vitamin B12 c. vitamin D
b. vitamin C d. vitamin E

Answer 132

d. vitamin E

Question 133

A college student tracks his diet for several weeks as part of a nutrition project. During the tracking
period, he realizes that his diet is rich in yellow and orange fruits and vegetables, citrus fruits, nuts, and
fish, but that he tends to avoid most leafy green vegetables. Which of the following vitamins is most
likely deficient in his diet?
a. vitamin B12 c. vitamin A
b. vitamin K d. vitamin C

Answer 133

b. vitamin K

Question 134

Minerals are
a. organic compounds.
b. required by the human body in small amounts.
c. not harmful to humans when ingested in large amounts.
d. created by chemical reactions within cells.

Answer 134

b. required by the human body in small amounts.

Question 135

Pancreatic cancer is an especially dangerous disease in humans because the pancreas is
a. the organ that produces and stores bile.
b. the site of synthesis for all the essential amino acids.
c. one of the organs through which food must pass on its way to the large intestine.
d. an organ that manufactures many different kinds of digestive enzymes

Answer 135

d. an organ that manufactures many different kinds of digestive enzymes

Question 136

Which of the following sequences correctly describes the journey of a potato chip through our digestive
tract?
a. mouth to esophagus to stomach to liver to small intestine to large intestine to anus
b. mouth to esophagus to stomach to small intestine to large intestine to anus
c. mouth to stomach to esophagus to pancreas to small intestine to large intestine to anus
d. mouth to esophagus to stomach to large intestine to small intestine to anus

Answer 136

b. mouth to esophagus to stomach to small intestine to large intestine to anus

Question 137

The advantage of chewing food is that this process
a. provides mechanical digestion and increases the surface area of the food for further
digestion.
b. makes food immediately ready for nutrient absorption in the stomach.
c. increases the amount of vitamins in the food.
d. decreases the surface area of the food to speed digestion.

Answer 137

a. provides mechanical digestion and increases the surface area of the food for further
digestion.

Question 137

The function of the esophagus is to
a. break down food physically.
b. break down food chemically.
c. carry food to the stomach.
d. prepare undigested material and waste for disposal.

Answer 137

c. carry food to the stomach.

Question 138

Food passing through our digestive tract would contain the fewest nutrients when it reaches which of the
following organs?
a. the small intestine c. the large intestine
b. the stomach d. the esophagus

Answer 138

c. the large intestine

Question 139

The human liver produces bile, a substance that
a. aids in the absorption of vitamin C.
b. allows fats to dissolve more easily in the watery contents of the gut.
c. neutralizes the acids that are produced by pepsin.
d. breaks the bonds between amino acids

Answer 139

b. allows fats to dissolve more easily in the watery contents of the gut.

Question 140

The liver secretes bile to the
a. pancreas. c. gallbladder.
b. small intestine. d. large intestine

Answer 140

c. gallbladder.

Question 141

One of the advantages of the villi that line the small intestine is that they
a. decrease the surface area available for food absorption.
b. increase the speed at which vitamins are broken down.
c. increase the amount of mechanical breakdown that occurs.
d. increase the surface area available for food absorption

Answer 141

d. increase the surface area available for food absorption

Question 142

Which of the following statements best explains why starch molecules must be broken down before they
can be absorbed by the small intestine?
a. They are toxic to the cells of the small intestine.
b. They are too large to pass through the plasma membrane of the intestinal cells.
c. They must be broken down in order to extract the essential amino acids they contain.
d. The cells of the small intestine are much too small to contain them.

Answer 142

b. They are too large to pass through the plasma membrane of the intestinal cells.

Question 143

How rapidly an organism can absorb nutrients generally depends on
a. the surface area available for absorption.
b. how quickly the nutrient can diffuse into the stomach.
c. the passive mechanisms that carry the nutrient into the organism.
d. the volume of the organism that is taking up the nutrients.

Answer 143

a. the surface area available for absorption.

Question 144

The lower region of the small intestine is structured to create large amounts of surface area so that it can
more efficiently
a. produce enzymes to break food down into smaller molecules.
b. grind food down into smaller molecules.
c. absorb the chemical building blocks that are produced by digestion.
d. eliminate waste products.

Answer 144

c. absorb the chemical building blocks that are produced by digestion.

Question 145

Which of the following would NOT be found in the lower small intestine?
a. microvilli c. a large surface area
b. villi d. a smooth surface

Answer 145

d. a smooth surface