Download Answers to Unit 6 practice test

1. In Darwin’s view of descent with modification
a. An organism’s traits only affect its own survival
b. Natural selection can improve the match between an organism and its
environment
c. Individuals can evolve
d. Environmental changes have no effect on the organisms living in that
environment
2. In the case of the Lake Victoria cichlids, sympatric speciation has been shown
to be driven by __________
a. Habitat differentiation
b. Mechanical isolation
c. Sexual selection
d. Post-zygotic barriers
3. Which of the following organisms are most likely to be subject to allopatric
speciation?
a. Whale populations of the same species located on opposite sides of
the Atlantic Ocean
b. Pine trees in Alaska and pine trees on the island of Madagascar
c. Mountain lions in the canyons of Wyoming and in the canyons of Utah
d. Fruit flies on bananas and fruit flies on oranges
4. The biological species concept emphasizes __________
a. Molecular differences ecological niches
b. The evolution of reproductive isolation
c. Morphological and structural features
d. Common ancestry
5. Which of the following is an example of a postzygotic reproductive barrier?
a. One species of frog mates in April, but another mates in May
b. Two fruit flies of different species produce sterile offspring
c. The sperm of a marine worm can only penetrate eggs of the same
species
d. One species of flower grows in forested areas, another in meadows
6. Three species of frogs all mate in the same ponds, but they pair off correctly
because they have different calls. This is an example of a _____ barrier, called
_____.
a. Prezygotic barrier, behavioral isolation
b. Postzygotic; hybrid breakdown
c. Prezygotic; temporal isolation
d. Postzytotic, mechanical isolation
7. Which of the following conditions is necessary for speciation to occur?
a. Reproductive isolation
b. Sympatric speciation
c. Adaptive radiation
d. Mass extinction
8. A population of squirrels is preyed on by hawks. The smaller squirrels can
escape into burrows, the larger squirrels can fight off the hawks. After
several generations, the squirrels tend to be very large or very small. What
process is responsible for this outcome?
a. Stabilizing selection
b. Directional selection
c. Disruptive selection
d. Balancing selection
9. Which of the following is the best example of gene flow?
a. A small population of humans colonizes a new island
b. Genes are shuffled by the crossing over of chromosomes during
meiosis
c. An earthquake results in the formation of a canyon, splitting a
population of toads apart
d. Wind blows pollen from one population of plants to another and
cross-fertilization occurs
10. An earthquake hits a small island. All but a small group of closely related
lizards are eliminated, and the survivors spread out over the island. This is
an instance of _____.
a. Founder effect
b. Bottleneck effect
c. Gene flow
d. Mutation
11. A population of 15 birds inhabits a fairly new island. Twn of the birds are
dark brown and five are light brown. By chance, two of the dark brown birds
and three of the light brown birds die before producing offspring. All of the
birds in the next generation are dark brown. This can be attributed to _____.
a. Natural selection
b. Genetic drift
c. Gene flow
d. Disruptive selection
12. In a certain group of African people, 4% are born with sickle-cell disease
(homozygous recessive). If this group is in Hardy-Weinberg equilibrium,
what percentage of the group has the selective advantage of being more
resistant to malaria (heterozygous) than those individuals who are
homozygous for normal hemoglobin or for sickle-cell disease?
a. 4%
b. 8%
c. 16%
d. 32%
13. In a population in Hardy-Weinberg equilibrium, 1% of the individuals in a
population show the recessive trait of a certain characteristic. In this
situation, what is the value of p?
a. 99%
b. 0.81
c. 0.9
d. 0.18
14. In a large population of bonobos, the frequency of the recessive allele is
initially 0.1. There is no migration and no selection. What is the frequency of
the dominant allele? Assume that there are two alleles of this gene.
a. 10%
b. 20%
c. 50%
d. 90%
15. In the context of populations, how do we define evolution?
a. A change in the population’s allelic frequencies over generations
b. Evolution is the tendency for some individuals in a population to leave
more offspring than others
c. Evolution is the way in which sexual reproduction can rapidly spread
advantageous traits throughout a population
d. Always caused by natural selection
16. To describe evolution as a “scientific theory” means that __________.
a. It is an untested idea
b. It is a matter of opinion
c. It is a broad model that is supported by many observations and much
experimental evidence
d. It can be considered dogma
17. When they were first sold, aerosol insecticides were highly effective in
killing flies and mosquitoes. Now, several decades later, a much smaller
proportion of these insects die when sprayed. The reason fewer insects die
when they are sprayed is that _____.
a. Mosquitoes that survive spraying develop an immunity to the
insecticide
b. Many mosquitoes today are descendants of mosquitoes with
insecticide-resistant characteristics
c. Mosquitoes are deliberately adapting themselves to this man-made
change in the environment
d. The original spraying has caused a permanent mutation, giving the
insects genetic resistance to the spray
18. The smallest unit that can evolve is a(n) __________.
a. Species
b. Genotype
c. Individual
d. Population