Download 22 Evolution Practice Questions

AP Biology -- John Burroughs School -- M. Bahe
Some Practice For Evolution & The Origin of Life
16-20from the REAL 2014, 2013 and 2012 AP Bio Exams)
(These Questions
question come
Questions 16-20
The three-spined
stickleback
(Gasterosteus
aculeatus) isaculeatus)
a small fishisfound
infish
bothfound
marine
and freshwater
The three-spined
stickleback
(Gasterosteus
a small
in both
marine and freshwater
The three-spined
stickleback
(Gasterosteus
aculeatus)
isofaindividuals
small
found
inwith
botharmor-like
marine
andcovering
freshwater
environments.
MarineMarine
stickleback
populations
consist
mainlymainly
with armor-like
plates
most most
environments.
stickleback
populations
consist
of fish
individuals
plates
covering
of their
body
surface
(completely
plated).
Approximately
10,000
years
ago,
some
marine
sticklebacks
colonized
environments.
Marine
stickleback
populations
consist
mainly
of
individuals
with
armor-like
plates
covering
most
of their body surface (completely plated). Approximately 10,000 years ago, some marine sticklebacks
colonized
freshwater
After many plated).
generations
in the freshwater
environments,
themarine
freshwater
stickleback
of freshwater
theirenvironments.
body surface
(completely
Approximately
10,000
years
ago,
some
sticklebacks
colonized
environments.
After(low
many
generations in
the
freshwater environments,
the freshwater stickleback
populations
lacked
the armor plating
plated) typical
of freshwater
marine stickleback
populations.
freshwater
environments.
After
many
generations
in
the
environments,
the
freshwater stickleback
populations lacked the armor plating (low plated) typical of marine stickleback populations.
populations lacked the armor plating (low plated) typical of marine stickleback populations.
Over the period between 1957 and 2005, one freshwater population, in Lake Washington, a lake in a coastal
Over
the period between
1957 and
2005, from
one freshwater
population,
in Lake Washington,
a lake in a coastal
region of the
northwestern
United States,
changed
having a majority
of individuals
of the low-plated
Overtothe
between 1957
and
2005, one
freshwater
population,
in
Lakeofthe
Washington,
a lake
in a coastalphenotyp
region
of period
the northwestern
United
changed
from having
a majority
individuals
of
the low-plated
phenotype
having
more individuals
of States,
the completely-plated
phenotype
than of
low-plated
phenotype.
region
of
the
northwestern
United
States,
changed
from
having
a
majority
of
individuals
of
the
low-plated
phenotype
Figure 1toshows
distribution
of plated
phenotypes in Lake
Washington
at fourphenotype.
time pointsFigure
havingthe
more
individuals
of the completely-plated
phenotype
thansticklebacks
of the low-plated
1 shows th
to distribution
having
more2005.
individuals
of
the
completely-plated
phenotype
than
of
the
low-plated
phenotype.
Figure
1
shows
between
1957 and
of plated phenotypes in Lake Washington sticklebacks at four time points between 1957 and
2005.the
distribution of plated phenotypes in Lake Washington sticklebacks at four time points between 1957 and 2005.
A single gene, ectodysplasin (EDA), is thought to be responsible for the variation in the number of armor plates in
A single
gene,
ectodysplasin
(EDA),
isconstructed
thought
to responsible
be
the
variation
in
of armor
plates
sticklebacks.
Figure
2 shows
a phylogenetic
tree
byresponsible
comparing
DNA
sequences
of the
the number
EDAofgene
from
A single
gene,
ectodysplasin
(EDA),
is
thought
to be
for for
the
variation
in the
number
armor
plates
in i
sticklebacks.
Figure
2
shows
a
phylogenetic
tree
constructed
by
comparing
DNA
sequences
of
the
EDA
gene
from
a number
of
stickleback
populations
with
low-plated
or
completely
plated
phenotypes.
Figure
3
shows
a
sticklebacks. Figure 2 shows a phylogenetic tree constructed by comparing DNA sequences of the EDA gene from a a
number
of
stickleback
populations
with
or
plated
phenotypes.
Figure
3from
shows
a phylogenetic
phylogenetic
tree
constructed
by comparing
thelow-plated
sequences
of completely
25 genesplated
that
were
randomly
selected
number
of
stickleback
populations
with
low-plated
or completely
phenotypes.
Figure
3 shows
athe
phylogenetic
same populations
as shown
in Figure 2.
Insequences
both figures,
shaded
populations
display the
completely
plated
tree
constructed
by
comparing
the
of
25
genes
that
were
randomly
selected
from
the
same
populations
tree constructed by comparing the sequences of 25 genes that were randomly selected from the same populations as as
phenotype.
shown in Figure 2. In both figures, shaded populations display the completely plated phenotype.
shown in Figure 2. In both figures, shaded populations display the completely plated phenotype.
Unauthorized
copying
or reuse
Unauthorized
copying
or reuse
of of
of this
page
is illegal.
anyany
partpart
of this
page
is illegal.
THE
NEXT
PAGE.
GOGO
ONON
TOTO
THE
NEXT
PAGE.
AP Biology -- John Burroughs School -- M. Bahe
You need the information on the previous page for these 4 questions.
1. Which of the following best explains the differences in the armor of the Lake Washington stickleback
population summarized in Figure 1 ?
a. ! Analysis of somatic cells using chromosomal staining and light microscopy indicates that stickleback fish
have a diploid number!of 42. !
b. Stickleback males from natural freshwater populations are typically more aggressive when competing for
mates than are stickleback males from laboratory-bred populations. !
c. Fish exhibiting the low-plated phenotype were selected against in the Lake Washington stickleback
population over the last 50 years. !
d. Migration of individuals from other freshwater environments to Lake Washington led to gene flow
between populations that were once geographically isolated.
2.
A completely-plated stickleback from a marine population was mated to a low-plated stickleback from a
freshwater population. The resulting F1 hybrids all displayed a completely plated phenotype. When the F1
hybrids were allowed to interbreed, the resulting F2 generation included completely plated offspring and
low-plated offspring in an approximate 3:1 ratio. Which of the following conclusions is best supported by the
results of the breeding experiments? !
a. Phenotypic variation in the F2 generation suggests that armor morphology is controlled by many alleles
of a single gene. !
b. The completely-plated phenotype is controlled by a dominant allele of a single gene. !
c. Armor loss is an acquired characteristic that is affected by one or more environmental factors. !
d. Patterns of armor plating in stickleback populations are regulated by sex-specific signals.
3.
Prior to 1960, Lake Washington was highly polluted and underwater visibility was limited to one or two
meters. In the late 1960s, a large cleanup effort reduced pollution, resulting in visibility that increased to six to
seven meters by 1976. Which of the following best explains how the change in underwater visibility affected
armor plating in Lake Washington sticklebacks between 1957 and 1976 ?
a. Higher visibility allowed sticklebacks to increase their food consumption to make armor production
easier.
b. Higher visibility made the sticklebacks more susceptible to large-toothed predators in the lakes, giving
complete armor a selective advantage.
c. Clearer water allowed sunlight to penetrate to deeper depths, so the sticklebacks had to increase the
amount of armor to protect themselves from the resulting increase in water temperature.
d. Clearer water contained fewer of the molecular building blocks needed for armor production, so
sticklebacks showed a reduction in the amount of armor.
4.
Evolution of a new trait typically takes many generations. Yet a dramatic shift in the extent of armor plating
in the Lake Washington stickleback population occurred in the 50 years following the cleanup of the lake.
Which of the following best describes the mechanism of the rapid evolution of the armor phenotype in the
Lake Washington sticklebacks?
a. Pollutants in Lake Washington forced the sticklebacks to increase their mutation rate.
b. The rapid change in the Lake Washington ecosystem required individual sticklebacks to evolve complete
armor quickly.
c. The increase in visibility in Lake Washington allowed sticklebacks to visually select mates with low
armor.
d. New selective pressures favored individuals with the plated phenotype, causing the plated allele
frequency in the population to quickly increase.
5.
The pesticide DDT was widely used in the 1940s as a method of insect control. In the late 1950s the first DDTresistant mosquitoes were discovered, and eventually DDT-resistant mosquitoes were found globally. When
DDT is used now, the development of DDT resistance in mosquito populations occurs in months rather than
years. Which of the following best explains the observations concerning DDT resistance in mosquitoes?
a. Competition for limited resources causes mosquitoes to migrate to geographical areas that have richer
supplies of DDT.
b. The proportion of DDT-resistant mosquitoes in a population remains constant due to the metabolic costs
of DDT utilization.
c. Natural selection favors DDT-resistant mosquitoes that are already present in a population when DDT
exposure occurs.
d. DDT is a chemical signal that delays normal reproductive cycles in many mosquito populations.
AP Biology -- John Burroughs School -- M. Bahe
6.
Methicillin-resistant Staphylococcus aureus (MRSA) can be a serious threat to human health. There is evidence
that S. aureus infections are common in hospitals and that MRSA have become resistant to other antibiotics
besides methicillin. This suggests that the rapid evolution of resistance in the bacteria poses a serious publichealth challenge. Which of the following best explains the ability of MRSA to evade existing drug therapies?
a. MRSA have very long generation times and very large population sizes.
b. MRSA develop new alleles by intentionally introducing specific mutations that will give them a selective
advantage over other bacteria.
c. MRSA metabolize many drugs in their lysosomes and therefore evolve resistance at a high rate.
d. MRSA exchange genetic material with other antibiotic-resistant bacteria, which can spread resistance in
the S. aureus population.
7.
Undersea landslides can disrupt marine habitats by burying
organisms that live on the ocean floor. The graph at right
shows the size of a population of a certain organism that lives
on the ocean floor. The population was affected by a recent
landslide at the time indicated on the graph. Which of the
following best predicts how the population will be affected
by the landslide?
a. The surviving organisms will evolve into a new species.
b. The reduced population will likely have allelic
frequencies that are different from the initial population. !
c. The population will adapt to deeper waters to avoid
future landslides. !
d. The reduced population will have a greater number of different genes than the initial population.
8.
Data regarding the presence (+) or absence (-) of five derived traits in several different species are shown in
the table below. Which of the following cladograms provides the simplest and most accurate representation
of the data in the table?
AP Biology -- John Burroughs School -- M. Bahe
You will need this information for the next 3 Questions.
Rhagoletis pomonella is a parasitic fly native to North America that infests fruit trees. The female fly lays her
eggs in the fruit. The larvae hatch and burrow through the developing fruit. The next year, the adult flies
emerge.
Prior to the European colonization of North America, the major host of Rhagoletis was a native species of
hawthorn, Crataegus marshallii. The domestic apple tree, Malus domestica, is not native to North America, but
was imported by European settlers in the late 1700s and early 1800s.
When apple trees were first imported into North America, there was no evidence that Rhagoletis could
use them as hosts. Apples set fruit earlier in the season and develop faster, where hawthorns set later and
develop more slowly.
Recent analysis of Rhagoletis populations has shown that two distinct populations of flies have evolved
from the original ancestral population of flies that were parasitic on hawthorns. One population infests only
apple trees, and the other infests only hawthorns. The life cycles of both fly populations are coordinated with
those of their host trees. The flies of each population apparently can distinguish and select mates with similar
host preferences and reject mates from the population specific to the other host tree. There is very little
hybridization (only about 5 percent) between the two groups.
9.
The divergence between the two populations of Rhagoletis must have occurred very rapidly because
a. the apple tree was imported into North America with European settlement approximately 200 years ago
b. flies were imported into North America with European settlement approximately!200 years ago
c. long-distance rail transport of fruit increased only after the American Civil War (1861–1865)
d. heavy use of gunpowder during the American Civil War (1861–1865) led to increased mutation rates in
many natural populations of plants and animals
10. Initially, which of the following isolating mechanisms is likely to have been the most important in preventing
gene flow between the two populations of Rhagoletis? !
a. Gamete incompatibility
b. Temporal isolation!
c. Mechanical isolation
d. Reduced hybrid viability
11. Matings between individuals from the!two populations of Rhagoletis produce hybrid flies that appear to be
healthy and have normal life spans. The eggs laid by these hybrid flies, however, hatch less often than those
of flies from either of the two populations. What isolating mechanism seems to be important in this hybrid
population?
a. !Prezygotic isolation!
b. Mechanical isolation
c. Reduced hybrid fertility
d. Habitat isolation
12. A group of mice was released into a large
field to which no other mice had access.
Immediately after the release, a
representative sample of the mice was
captured, and the fur color of each
individual in the sample was observed
and recorded. The mice were then
returned to the field. After twenty years,
another representative sample of the mice
was captured, and the fur color of each
individual in the sample was again
recorded. Which of the following best
explains the change in the frequency
distribution of fur color phenotypes in the mouse population, as shown in the figures above?
a. The allele for gray fur color is unstable, and over twenty years most of those alleles mutated to become
alleles for black fur.
b. The field was composed primarily of light-colored soil and little vegetation, affording gray mice
protection from predators.
c. Sexual selection led to increased mating frequency of black and brown versus gray and brown.
d. The gray mice were hardest to capture and so were underrepresented in the twenty-year sample.
AP Biology -- John Burroughs School -- M. Bahe
13. Scientists have found that the existing populations of a certain species of amphibian are small in number,
lacking in genetic diversity, and separated from each other by wide areas of dry land. Which of the following
human actions is most likely to improve the long-term survival of the amphibians?
a. Cloning the largest individuals to counteract the effects of aggressive predation
b. Reducing the population size by one-fifth to decrease competition for limited resources
c. Constructing a dam and irrigation system to control flooding
d. Building ponds in the areas of dry land to promote interbreeding between the separated populations
14. To determine the evolutionary history and relationships
among organisms, scientists gather evidence from a
wide variety of sources including paleontology,
embryology, morphology, behavior, and molecular
biology. A phylogenetic tree of vertebrates is shown.
Which of the following statements is most consistent
with the phylogenetic tree shown?
a. Birds and turtles evolved their own means of gas
exchange independently of the other vertebrates.
b. Mammals are most closely related to birds because
they share a direct common ancestor.!
c. The common ancestor of reptiles, birds, and
mammals produced amniotic eggs.!
d. Crocodiles are direct descendents of ray-finned
fishes since they live in the same environment.
15. Ellis-van Creveld syndrome is a recessive genetic disorder that includes the characteristics of short stature
and extra fingers or toes. In the general population, this syndrome occurs in approximately 1 in 150,000 live
births. In a particular isolated population, however, the incidence of this syndrome among live births! is 1 in
500.
Assume that both the isolated population and!the general population are in Hardy-Weinberg equilibrium
with respect to this syndrome. Which of the following best describes the difference between the frequency of
the allele that causes the syndrome in the general population and the frequency of the allele in the isolated
population?
a. The frequency of the Ellis-van Creveld allele is 0.002 in the isolated population and 0.0000066 in the
general population,!which suggests that selection for this trait is occurring in both populations.
b. The frequency of the Ellis-van Creveld allele is 0.0447 in the isolated population and 0.0026 in the general
population, showing that the rate of genetic mutation is highest among individuals in the isolated
population.
c. The frequency of the Ellis-van Creveld allele is 0.002 in the isolated population and 0.0000066 in the
general population, which demonstrates gametic incompatibility between the populations.
d. The frequency of the Ellis-van Creveld allele is 0.0447 in the isolated population and 0.0026 in the general
population, which suggests that genetic drift has occurred in the isolated population.
16. Which of the following statements best supports the claim that organisms share fundamental processes as a
result of evolution?
a. All organisms that are introduced into new environments have the capacity to fill vacant ecological roles.
b. All organisms have the ability to utilize oxygen to harness energy from the chemical breakdown of
organic compounds.
c. All organisms share a genetic code organized into triplet codons, making it possible for one organism to
express a gene from another organism.
d. All organisms possess structures such as chloroplasts and mitochondria within their cells that reflect past
symbiotic relationships between prokaryotic precursors.
AP Biology -- John Burroughs School -- M. Bahe
For the Next 4 questions:
A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It
was determined that the average beak size (both length and mass) of finches in a certain population increased
dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the
number of plants producing thin-walled seeds.
17. Which of the following procedures was most likely followed to determine the change in beak size? !
a. A few finches were trapped in 1981 and again in 1987, and their beak sizes were compared. !
b. The beak size in fifteen finches was measured in 1987, and the beak size in the original finches was
determined by estimation. !
c. The beak size in a large number of finches was measured every year from 1981 to 1987. !
d. Finches were captured and bred in 1981, and the beak size of the offspring was measured.
18. Which of the following statements might best explain the increase in average beak size in the finch
population during the drought? !
a. Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving
offspring.
b. Finches with bigger beaks can attack and kill finches with smaller beaks.
c. Finches with bigger beaks possess more- powerful flight muscles and are able to find more food
d. Finches that crack large seeds develop larger beaks over time.
19. Which of the following best describes the mechanism behind the change in beak size in the finch population?
a. The formation of two new finch species from a single parent species.
b. A change in gene frequencies in the finch population due to selective pressure from the environmental
change.
c. A new allele appearing in the finch population as a result of mutation.
d. The achievement of dynamic equilibrium in the finch population as a result of homeostasis.
20. The biologist discovered that from 1988 to 1993, the average beak size declined to pre-1981 levels. The
reversal in beak size from 1988 to 1993 was most likely related to which of the following events?
a. A loss of food supply for the finches!
b. The end of the drought!
c. An increase in drought conditions!
d. An increase in predators consuming finches
21. Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of
rRNA subunits were determined for the new species. The table below shows the number of nucleotide
differences between the species. Which of the following phylogenetic trees is most
consistent with the data?
AP Biology -- John Burroughs School -- M. Bahe
22. Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms
from all three domains, Archaea, Bacteria, and Eukarya. Which of the following hypotheses could be best
supported by this evidence?
a. All organisms carry out glycolysis in mitochondria.
b. Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms
of life.
c. Across the three domains, all organisms depend solely on the process of anaerobic respiration for ATP
production.
d. The presence of glycolysis as an energy- releasing process in all organisms suggests that convergent
evolution occurred.
23. A group of students summarized information on five great extinction events in the table above. The students
are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following
would be the most reasonable plan for the students to follow?
a. Searching horizontal rock layers in any class of rock and try to find those that contain the greatest
number of fossils
b. Collecting fossils from rock layers deposited prior to the Permian period that contain some early
vertebrate bones
c. Looking in sedimentary layers next to bodies of water in order to find marine fossils of bivalves and
trilobites
d. Using relative dating techniques to determine the geological ages of the fossils found so they can
calculate the rate of speciation of early organisms
AP Biology -- John Burroughs School -- M. Bahe
24. CALCULATION PROBLEM: Researchers observe a large population of birds on a remote island. Birds in the
population are found to have either red crest feathers or white crest feathers on their heads. Genetic analysis
indicates that the allele for red crest feathers is dominant over the allele for white crest feathers. In a survey of
the population, the researchers determine the frequencies of the crest-feather phenotypes. The results of the
survey are shown in the table below.
Frequencies of Phenotypes in an isolated Bird
Population
Phenotype
Number of Individuals
Red Crested Feathers
11,088
White Crested Feathers
1,759
Assuming that the bird population is in Hardy- Weinberg equilibrium, what proportion of future populations
is expected to be heterozygous for the allele controlling crest feather color? Give your answer as a value
between 0 and 1, rounded to two decimal places.
25. CALCULATION PROBLEM: Some people have the ability to taste a bitter chemical called
phenylthiocarbamide (PTC). The ability to taste PTC is due to the presence of at least one dominant allele for
the PTC taste gene. The incidence of nontasters in North America is approximately 45%. Assuming the
population is in Hardy-Weinberg equilibrium, what percent of the North American population is
homozygous dominant for the ability to taste PTC? Provide your answer as a number between 0 and 1 to the
nearest hundredth.
26. CALCULATION PROBLEM: In a population of certain frogs in which the allele for brown skin is dominant
to the allele for green skin, a drought leads to selection against green-skinned frogs. When the drought
ends,!12 percent of the remaining frogs exhibit the green-skin phenotype. If the population is now in HardyWeinberg equilibrium, what will be the frequency of the green-skin allele in the next generation? Provide
your answer to the nearest hundredth.
AP Biology -- John Burroughs School -- M. Bahe
The remaining questions are short answer (paragraph) answers. Write the answers on a separate sheet of paper.
27. In a study of bacterial communities, researchers investigated interactions among naturally occurring strains
of Vibrio bacteria. The researchers found that some Vibrio
bacteria secrete antimicrobial substances that inhibit the
growth and reproduction of other bacteria (antagonism). The
researchers also found that some strains of Vibrio bacteria
produce no antimicrobial substances themselves but instead
live in close proximity to other bacteria that produce
antimicrobial substances to which they are not susceptible
(cooperation).
By testing approximately 35,000 pairs of naturally occurring
strains of Vibrio bacteria, the researchers identified 830
antagonistic interactions among genetically related Vibrio
strains. The graph represents the probability of antagonism
between any two given strains of Vibrio bacteria as a function
of genetic relatedness (genetic distance). The greater the
genetic distance, the less related are any two bacterial strains.
a. Describe ONE type of molecular evidence that can be used to determine the genetic relatedness of
6. Innaturally
a study of
bacterialpopulations.
communities, researchers investigated interactions among natur
bacterial strains isolated from
occurring
Vibrio
bacteria.
The
researchers
found that between
some Vibrio
bacteria and
secrete
antimicrobial
b. Using the information presented in the graph, describe the relationship
antagonism
genetic
growth
and
reproduction
of
other
bacteria
(antagonism).
The
researchers
also found th
relatedness in the communities of Vibrio bacteria sampled for the study.
bacteria
produce
no
antimicrobial
substances
themselves
but
instead
live
in close prox
c. Provide reasoning to show how the results of the study support the claim that cooperation among Vibrio
bacteria can increase the fitness
of some
individual bacteria
living
in a natural
environment.
produce
antimicrobial
substances
to which
they are
not susceptible (cooperation).
Byare
testing
approximately
35,000
of naturally
occurring
strains
28. Fossils of lobe-finned fishes, which
ancestors
of amphibians,
arepairs
found
in rocks that
are at least
380of Vibrio bacteria
830 antagonistic
interactions
among
genetically
Vibrio
strains.
The graph repr
million years old. Fossils of the oldest
amphibian-like
vertebrate
animals
with truerelated
legs and
lungs
are found
antagonism
between
in rocks that are approximately 363
million years
old. any two given strains of Vibrio bacteria as a function of genetic r
Three samples of rocks are available
that might
fossils
of a transitional
between
distance).
The contain
greater the
genetic
distance, thespecies
less related
are lobe-finned
any two bacterial strain
fishes and amphibians: one rock sample that is 350 million years old, one that is 370 million years old, and
one that is 390 million years old. (a) Describe ONE type of molecular evidence that can be used to determine the gene
strains
isolated
from to
naturally
occurring
populations.
a. Select the most appropriate sample
of rocks
in which
search for
a transitional
species between lobefinned fishes and amphibians. Justify your selection.
(b) Using
the information
in the
graph,that
describe
relationship
between a
b. Describe TWO pieces of evidence
provided
by fossils ofpresented
a transitional
species
wouldthe
support
a
relatedness
in
the
communities
of
Vibrio
bacteria
sampled
for
the
study.
hypothesis that amphibians evolved from lobe-finned fishes.
(c) Provide reasoning to show how the results of the study support the claim that coo
29. In fruit flies (Drosophila melanogaster), straight wing shape is dominant to curly wing shape. A particular
bacteria can increase the fitness of some individual bacteria living in a natural env
population of fruit flies is in Hardy-Weinberg equilibrium with respect to the alleles for wing shape.
The Hardy-Weinberg equation, given below, is useful in understanding population genetics:
2
PAGE FOR ANSWERING
6
p2 +2pq+qQUESTION
=1
a.
b.
2
2
Explain what the terms ( p , 2pq, and q ) represent in the population of fruit flies.
Describe one condition that is necessary for the population to be in equilibrium.
30. Populations of a plant species have been found growing in the mountains at altitudes above 2,500 meters.
Populations of a plant that appears similar, with slight differences, have been found in the same mountains at
altitudes below 2,300 meters.
a. Describe TWO kinds of data that could be collected to provide a direct answer to the question, do the
populations growing above 2,500 meters and the populations growing below 2,300 meters represent a
single species?
b. Explain how the data you suggested in part (a) would provide a direct answer to the question.
31. Fossils of a microscopic organism are found in rocks determined to be over 3.5 billion years old. Identify
TWO types of evidence that would help answer the question of whether the organism was photosynthetic.
Amino Acid 104
Arginine (Arg)
Lysine (Lys)
Arginine (Arg)
Arginine (Arg)
Figure 2. Codon Table
-18-
GO ON TO THE NEXT PAGE.
Figure 1. Student-constructed Phylogenetic
Tree of Vertebrate Species with
Incorrect Placement of “Lys”
A student constructed the phylogenetic tree shown in Figure 1 by comparing the amino acid sequences of
-hemoglobin in the four species. The student placed “Lys” at an incorrect position on the phylogenetic tree
in an attempt to show when the mutation affecting amino acid 104 occurred.
-hemoglobin is a highly conserved protein among vertebrates. The identity of amino acid 104–one of the
variable amino acids in the polypeptide–in four vertebrate species is shown in the table above.
Unauthorized copying or reuse of
any part of this page is illegal.
3.
Species
Horse
Gorilla
Chimpanzee
Human
AMINO ACID AT POSITION 104 OF -HEMOGLOBIN
Unauthorized copying or reuse of
any part of this page is illegal.
PAGE FOR ANSWERING QUESTION 3
-19-
GO ON TO THE NEXT PAGE.
(b) Predict the most likely single mutation affecting amino acid 104 in the species and justify how
-hemoglobin can function normally in all four species despite the mutation.
(a) Refine the student’s model by placing “Lys” at the correct position on the phylogenetic tree to indicate
where the Arg-to-Lys mutation most likely occurred. Provide ONE piece of reasoning to support your
placement of “Lys” on the phylogenetic tree.
AP Biology -- John Burroughs School -- M. Bahe
Question #32