Biology 112 – First
Hour Exam Name
MULTIPLE CHOICE. Choose the
one alternative that best completes the statement or answers the question.
1. (1 Point) Which of the
following steps is NOT vital to a well-designed experiment?
A)
A control group is included
B)
All variables but the one being tested are equally applied to all treatments
C)
Experiments are repeated on many individuals (replication)
D)
All of the above are vital.
2. (1 Point) Which statement
best represents the meaning of the term evolution:
A) The strongest individuals produce the most
offspring
B)
Changes in an individual over time in response to natural selection
C) Changes in gene frequencies in a population over time
D)
Changes in species complexity over time
3. (2 Pts) Over the past
several decades, natural selection has caused populations of Staphylococcus
aureus (an infectious wound
bacterium) to evolve resistance to most antibiotics. If antibiotic use were
stopped, what would you predict would happen to these S. aureus populations?
A) They will go
extinct without the antibiotic.
B)
The frequency of resistant forms will increase in these populations.
C)
The populations will begin colonizing new environments.
D)
The frequency of nonresistant forms will increase in these populations.
4. (2 Pts) Starting from the
wild mustard Brassica oleracea,
breeders have created the strains known as brussels sprouts, broccoli, kale,
and cabbage. Which of the following statements is supported by this
observation?
A) In this species, there is enough heritable variation to create a variety of features.
B)
Natural selection has not occurred very frequently in the wild populations.
C)
Heritable variation is low-otherwise the wild strain would have different
characteristics.
D) In this species,
most of the variation present is due to differences in soil, nutrition, amount
of sunlight, or other aspects of the environment.
5. (1 Point) Which of the
following would not be a good reason for studying SSU RNA to understand the
major branches in the evolutionary history of life?
A)
It is a necessary part of the cellular machinery for reproduction and other
purposes.
B) It mutates very frequently.
C)
This molecule is found in every species.
D)
It is passed on through evolutionary history with only minor modifications.
6. (1 Point) On the tree of
life, the branch leading to animals is closer to fungi than it is to the branch
leading to land plants. Which of the following statements is correct?
A)
Animals and land plants are more closely related to each other than either is
to fungi.
B)
Animals and plants do not have a common ancestor.
C)
Fungi and animals do not have a common ancestor.
D) Animals and fungi are more closely related to each other than animals are to land plants.
7. (1 Point) You sequence
the genes that code for an important glycolytic enzyme in a moth, a mushroom, a
worm, and an alga and find a high degree of sequence similarity among these
distantly related species. This is an example of:
A) genetic homology
B)
developmental homology
C)
structural homology
D)
analogy/convergent evolution
8. (2 Pts) Claytonia
virginica is a woodland spring herb
with flowers that vary from white to pale pink to bright pink. Slugs prefer to
eat pink-flowering over white-flowering plants (due to chemical differences
between the two), and plants experiencing severe herbivory were more likely to
die. The bees that pollinate this plant prefer also prefer pink to white
flowers, so that Claytonia with pink flowers have greater relative fruit set
(reproductive success) than Claytonia with white flowers. A researcher observes
that the percentage of different flower colors remains stable in the study
population from year to year. If the researcher removes all slugs from the
study population, what would you expect to happen to the distribution of flower
colors in the population over time?
A)
The distribution of flower colors should not change.
B)
The percentage of white flowers should increase over time.
C) The percentage of pink flowers should increase over time.
D)
The distribution of flower colors should randomly fluctuate over time.
9. (2 Pts) Suppose 64% of a
remote mountain village can taste phenylthiocarbamide (PTC) and must therefore
have at least one copy of the dominant PTC taster allele (i.e. are heterozygous
or homozygous for PTC taster allele). If this population conforms to
Hardy-Weinberg expectations for this gene, what percentage of the population
must be heterozygous for this trait?
A)
48%
B)
40%
C)
16%
D)
32%
E)
60%
10. (2 Pts) The Dunkers are
a religious group that moved from Germany to Pennsylvania in the mid-1700s.
They do not marry with members outside their own immediate community. Today,
the Dunkers are genetically unique and differ in gene frequencies, at many
loci, from all other populations including their original homeland. Which of
the following likely explains the genetic uniqueness of this population?
A)
sexual selection and inbreeding depression
B)
heterozygote advantage and stabilizing selection
C)
population bottleneck and Hardy-Weinberg equilibrium
D)
mutation and natural selection
E) founder effect and genetic drift
11. (1 Point) Mutation is
the ultimate source of genetic variability. Why is this statement correct?
A)
DNA polymerase (the enzyme that copies DNA) is remarkably accurate.
B)
"Mutation proposes and selection disposes."
C)
Mutation occurs in response to natural selection. It generates the alleles that
are required for a population to adapt to a particular habitat.
D) Mutation is the only source of new alleles.
12. (1 Point) What is a
population?
A)
A population is any group of many individuals of the same species.
B)
A population is two or more groups that regularly interbreed.
C) A population is a group of individuals that live in the same area and that regularly interbreed.
D)
A population is a group of interacting species that live in the same area.
13. (1 Point) Which of the
following does not tend to promote speciation?
A) polyploidy
B) gene flow
C) natural selection
D)
the founder effect
14. (1 Point) Which of the
following statements explains why animals are less likely than plants to
speciate by polyploidy?
A)
Animals are better at recognizing appropriate mates.
B)
Animals are more mobile, so populations get separated far less often.
C) Animals rarely self-fertilize, so diploid gametes are much less likely to fuse.
D)
Animals have better mechanisms for repairing chromosomes than plants have.
15. (2 Pts) The two key
factors responsible for speciation among populations are:
A)
lack of gene flow and mutation
B) reproductive isolation and genetic divergence
C)
postzygotic isolation and morphological change
D)
mutation and genetic drift
16. (1 Point) A monophyletic
group would be best described as:
A)
a grouping of all species that share a similar set of traits
B)
a grouping of species descended from two or more closely related species
C)
a grouping of all species descended from a common ancestor, excluding that
ancestor
D) a grouping of
all species descended from a common ancestor, including that ancestor
17. (1 Point) Which of the
following would best be described as a case of speciation in sympatry?
A)
A population of lizards is subdivided by a natural barrier and subsequently
diverges to form two species that cannot interbreed.
B)
Speciation cannot take place in sympatry - only in allopatry, where geography
poses a barrier to gene flow.
C)
A new, isolated population of fruit flies is founded by a small group of
colonists, which then diverge from the ancestral source population.
D) An individual hermaphroditic plant undergoes meiotic failure, producing diploid pollen and ovules; these self-fertilize, germinate, and grow into several fully fertile tetraploid plants.
18. (1 Point) You find a new
fossil deposit, containing many species with shells but no soft-bodied species.
What is the most logical conclusion?
A) Conditions were not right to fossilize soft-bodied organisms.
B)
There were no soft-bodied organisms at this time and location.
C)
There was a mass extinction event among hard-bodied but not soft-bodied species
at this location.
19. (2 Pts) Applying the
principle of parsimony to the trait "ability to fly," which of the
two phylogenetic trees above is better?
A)
Tree 1 B)
Tree 2
21. (2 Pts) These graphs
show percentage change in three different molecular sequences plotted against
time. Which of these would make a good candidate for a molecular clock?
A)
graph A, because the curve levels off over time
B)
graph B, because DNA is more important to organisms and therefore will give a
more accurate picture of divergence
C)
graph C, because the change in sequence is the most rapid
D) graph B or C, because they are straight lines
E)
graph A or C, because amino acid changes in are more likely to be neutral DNA
changes in DNA
22. (1 Point) What types of
changes in the regulation of development can lead to morphological changes that
can be significant in evolution?
A)
changes in where developmental genes are expressed
B)
changes in when developmental genes are expressed
C) both A and B
D)
None of the above has ever been demonstrated.
SHORT ANSWER.
25. (5 Pts) Name five ways
in which the fossil record is biased.
1. Habitat bias –
certain habitats more likely to produce fossils than others
2. Hard-shelled organisms
favored over soft-bodied organisms
3. Tooth, bone, other
hard body parts favored over soft-bodied organisms
4. Temporal bias –
recent fossils more likely to be found; oldest rocks have been subducted into
the mantle and destroyed
5. Abundant species more
likely to appear in fossil record than are rare species
6. Very small sample size
relative to number of organisms because dead organisms usually decompose before
they are fossilized
7. Above ground organisms
more likely than those living underground
26. (5 Pts) Which of the
following isolating mechanisms are prezygotic and which are postzygotic?
(Circle either PRE or POST)
+
Land iguana eggs can't be fertilized by marine iguana sperm.
PRE POST
+
Mules-horse-donkey hybrids-are sterile.
PRE
POST
In
a forest, one beetle species lives on oaks and another beetle species lives on
pines.
PRE POST
+
In closely related bird species, males sing different courtship songs.
PRE POST
+
Hybrid seeds from pollination of one yucca by another yucca species are
aborted.
PRE
POST
27. (3 Pts) What does it
mean when we say Òfitness is relativeÓ?
Fitness is defined in terms of reproductive success relative to others in the population. It is calculated as reproductive success in proportion to the most successful form in the population.
28. (6 pts) How is
stabilizing selection different from disruptive selection and directional
selection? Frame your answer with respect to how the mean value for a trait
changes in a population.
1. Stabilizing selection selects for the existing
mean value of the trait. Thus, the mean value does not change over time.
2. Disruptive selection selects for both extremes
simultaneously. Thus, the mean value does not change over time, though the
number of individuals with the mean value decreases. The distribution loses its
normal distribution (bell shaped curve).
3. Directional selection selects for one extreme
only. Thus, the mean value of the trait is pushed toward that extreme (either
increasing the mean, or decreasing the mean).
29. (10 pts) What are the
necessary conditions for natural selection to occur within a population?
1. Variation in a trait in the population
2. The trait is heritable, at least to some extent.
3. Differential Reproductive success based on that
trait
4. (usually) Competition for resources.
30. (8 pts) How are
hypotheses and predictions related and what does falsifiability have to do with
the Scientific Method? Give one example to illustrate how hypotheses and
predictions are related.
A hypothesis is an general explanation for a phenomenon. Predictions are results of hypotheses, in that they designate what should happen in specific instances if those hypotheses are correct. The scientific method begins with observations and questions in regard to the observed phenomena. Hypotheses are provisional answers that may explain these questions. Predictions are then made that can be tested. The hypotheses must make predictions than can be proven wrong – i.e., falsified. If the hypothesis is tested and proven wrong, it is rejected. If it is tested and not proven wrong, then we begin to believe it. If it withstands repeated testing without being rejected, then it becomes a theory.
Many examples could be given.
32. (4 pts) What are
vestigial traits and why are they considered evidence for evolution by natural
selection?
Vestigial traits are those which are present in an organism/species, but have no apparent current function. They are often diminished in size. They serve as evidence for evolution because they are indicators of relatedness to closely related species with similar traits, but still in use. They are evidence of structural homologies that are no longer useful for this species.
33. (3 pts) Why can sexual
selection be considered a subset of natural selection?
Sexual selection is a
special case of natural selection, in that the competition between individuals
is for mating opportunities, not survival. Thus, traits arise through sexual
selection that may be detrimental to survival, but endow the possessor with an
advantage in gaining reproductive success – i.e., differential
reproductive success based on that trait.