1. Which of the following is a way in which variations
can arise in a population?
a. natural selection
b. mutation
c. crossing over during meiosis
d. both B and C
d. both B and C
2. Tail length in mice varies within a population. Scientists observed change in the
distribution of tail lengths in a mouse population over time. At the genetic level, what has
most likely happened to the allele for the shortest tail lengths?
a. The allele changed from being dominant to being recessive.
b. The allele changed from being autosomal to being sex-linked.
c. The allele became less frequent than the alleles for longer tail lengths.
d. The allele began to code for long tail lengths instead of the shortest ones.
c. The allele became less frequent than the
alleles for longer tail lengths.
3. Which of the following best describes natural
selection?
a. Individuals who adapt during their lifetime are
more likely to survive and reproduce.
b. Individuals born with certain favorable traits are
more likely to survive and reproduce.
c. There are little or no variations in populations,
which makes adaptations rare over time.
d. Individuals with little or no variation are more
likely to survive and reproduce.
b. Individuals born with certain
favorable traits are more likely
to survive and reproduce.
4. The frequency of an allele in a fly population changes
from 89% to 20% after three generations. Which other
events most likely occurred during the same time period?
a. An environmental change and a fly population
increase.
b. An environmental change and a fly population
decrease.
c. Interbreeding of flies with an invasive species and fly
population speciation.
d. Interbreeding of flies with an established local
species and fly population speciation.
b. An environmental change and a fly
population decrease.
5. If early Viking explorers in Greenland and North
America had survived and become the main ancestors
of early North American settlers, rather than the
mixture of immigrants from across Europe and other
continents, today there would be a much higher
incidence of Nordic traits in the US population. Such a
scenario would demonstrate
a. gene flow from continent to continent.
b. the founder effect.
c. genetic drift among the original Viking explorers.
d. directional selection.
b. the founder effect.
6. What is the correct order of the steps regarding
speciation?
a. one species  geographic isolation  divergent
evolution  reproductive isolation  two species
b. one species  reproductive isolation  divergent
evolution  geographic isolation  two species
c. one species  divergent evolution  geographic
isolation  reproductive isolation  two species
d. one species  geographic isolation  reproductive
isolation  divergent evolution  two species
d. one species  geographic isolation 
reproductive isolation  divergent evolution
 two species
Use the diagram below to answer questions 7-8.
7. The similarity of these structures suggests that the
organisms
a. have a common ancestor.
b. evolved slowly.
c. all grow at different rates.
d. live for a long time.
a. have a common ancestor.
8. An analysis of the DNA from these organisms
would indicate that
a. their DNA is identical.
b. they all have tails.
c. their DNA sequences show many similarities.
d. they all have the same number of
chromosomes
c. their DNA sequences show many similarities.
9. Bulldogs have been bred by humans for increasingly
large heads. This has made the birthing process more
difficult for the mother, and may decrease survival among
newborn pups. This intentional breeding is an example of
a. natural selection.
b. founder effect.
c. genetic drift.
d. artificial selection.
d. artificial selection.
10. What is the difference between a variation and an
adaptation?
• Variations are little differences
within a population that play no role
in fitness.
• Adaptations play a role in fitness,
and everyone within a population
exhibits the trait.