Download Answer Key - cloudfront.net

Answer Key
Chapter Test B
Multiple Choice
1.
2.
3.
4.
5.
6.
a
b
b
d
c
a
7.
8.
9.
10.
11.
12.
13.
14.
15.
c
d
c
b
b
d
a
d
b
Copyright by McDougal Littell, a division of Houghton Mifflin Company
Short Answer
16. directional selection
17. Directional selection
occurs when one extreme
phenotype is favored by
natural selection.
18. The graph would shift back
toward the left. The mean
value of the number of
spines would shift toward
plants with lower numbers
of spines.
19. 110
20. The peccaries are eating
more cacti with fewer
spines, so cacti with a
greater number of spines
are being selected for.
species become extinct
during these global events.
23. The oldest mass extinction
event occurred about 480
million years ago. The
next event occurred about
400 million years ago. The
next two occurred about
250 million years ago and
214 million years ago.
The last occurred about 56
million years ago. (Allow
estimates close to these
numbers, because the graph
is imprecise.)
24. the theory of punctuated
equilibrium
25. Mass extinctions are
the result of global
catastrophes, during which
a large portion of the
species on Earth become
extinct. These events
open up large portions
of Earth’s land and/or
marine environments.
Organisms that survive the
mass extinction event may
undergo a rapid burst of
evolution and diversify to
fill the open environments.
Global diversity often
changes dramatically after
a mass extinction event.
21. The five mass extinction
events in the fossil record.
22. Mass extinctions occur
as a result of global
catastrophes. These events
result in extinction rates
than are much higher that
the normal background
extinction rate. Many
Answer Key
1
CHAPTER
THE EVOLUTION OF POPULATIONS
11
Chapter Test B
Multiple Choice
Choose the letter of the best answer. (15 credits)
1. A population of squirrels that contains a
wide range of phenotypes has a
a. large amount of genetic variation.
b. high allele frequency for most
2. Mutations in the DNA of genes that can
be passed on to offspring
shows a normal distribution. On a
graph, this frequency would produce
what kind of curve?
a. shifted right
c. tall and thin
b. doubled
d. bell-shaped
5. Disruptive selection occurs when
selective pressures favor phenotypes
that are
a. close to the mean.
b. toward one extreme.
a. are more likely with genetic drift.
c. at both extremes.
b. result in increased genetic variation.
d. in a normal distribution.
c. do not occur randomly during
cactus population under pressure from
peccaries (wild pigs) and parasitic
insects. The dashed line shows the
original cactus population. What type of
selection does the graph show?
Number of cacti
Copyright © McDougal Littell/Houghton Mifflin Company.
3. Figure 11.1 shows the change in a
30
peccaries
parasitic
insects
6. Figure 11.2 shows a graph of
reproductive success versus tail feather
length for male widowbirds. What type
of selection is shown by these data?
2.0
Average nests per male bird
evolution.
d. are always harmful to the offspring.
CHAPTER 11
The Evolution of Populations
alleles.
c. poor chance of surviving habitat
change.
d. decreased chance of frequent gene
flow.
4. In a population of foxes, tail length
1.5
Shortened
Control 1
Control 2
Lengthened
1.0
0.5
0.0
20
FIG. 11.2
10
60
70 80
FIG. 11.1
a. sexual
c. stabilizing
b. disruptive
d. divergent
90 100 110 120 130
Number of spines
a. directional
c. intermediate
b. stabilizing
d. disruptive
Assessment Book
McDougal Littell Biology
Tail feather treatment
Chapter Test B
221
CHAPTER TEST B, CONTINUED
population must be
a. gene flow following disruptive
gene flow, no mutations, no natural
selection.
b. very large, have random mating,
high gene flow, many mutations,
natural selection.
c. small, have nonrandom mating,
no gene flow, many mutations, no
natural selection.
d. very large, have random mating, no
gene flow, no mutations, no natural
selection.
selection.
b. microevolution by reproductive
isolation.
c. genetic drift through the bottleneck
effect.
d. speciation triggered by the founder
effect.
8. What occurs when some elephants in a
population migrate into another area and
join another population?
a. genetic drift
c. speciation
b. microevolution
d. gene flow
9. A river has cut a deep canyon that
has separated a population of rodents
into two groups. This separation is an
example of what type of isolation?
a. temporal
c. geographic
b. behavioral
d. founder
10. The evolution of hummingbirds’ beaks
and plants with deep tubes in their
flowers is an example of
a. convergence.
c. speciation.
b. coevolution.
d. radiation.
11. For a certain population, the actual
frequencies of a genotype did not match
the genotype frequencies predicted by
the Hardy-Weinberg equation. What can
be said about the population?
222
12. To be in Hardy-Weinberg equilibrium, a
the palm trees in an area. This event will
most likely lead to
a. very small, have random mating, no
13. In a population of rattlesnakes that
is evolving, which of the following
statements is most likely true?
a. The rates of gene flow and mutation
are high.
b. The population is in Hardy-Weinberg
equilibrium.
c. Directional selection is probably not
occurring.
d. Natural selection has no effect on
this population.
14. When individuals from two populations
of squirrels can no longer successfully
mate with one another, the chance that
speciation will occur
a. decreases.
c. stays the same.
b. becomes zero.
d. increases
15. The wings of robins and the wings of
dragonflies are examples of
a. Allele frequencies are declining.
a. divergent adaptation.
b. The population is evolving.
b. convergent evolution.
c. No mutations are occurring.
c. adaptive radiation.
d. Gene flow does not occur.
d. punctuated equilibrium.
Chapter Test B
Assessment Book
McDougal Littell Biology
Copyright © McDougal Littell/Houghton Mifflin Company.
CHAPTER 11
The Evolution of Populations
7. A tsunami has destroyed almost all of
CHAPTER TEST B, CONTINUED
Short Answer Use the diagram below to answer items 16–20. (5 credits)
20
CHAPTER 11
The Evolution of Populations
Number of cacti
30
10
60
70 80 90 100 110 120 130
Number of spines
FIG. 11.3
16. In a desert environment, cacti are eaten by peccaries, a type of wild pig. What type of
selection is shown in Figure 11.3?
Copyright © McDougal Littell/Houghton Mifflin Company.
17. How does this type of selection occur?
18. What would happen to the graph if the peccaries began eating more of the very spiny
cacti?
19. What is the most common number of spines in the new cactus population?
20. Why are cacti with the most spines becoming more common?
Assessment Book
McDougal Littell Biology
Chapter Test B
223
CHAPTER TEST B, CONTINUED
Use the diagram below to answer items 21–25. (5 credits)
Extinction rate
(families per million years)
CHAPTER 11
The Evolution of Populations
20
15
10
5
Approximate
background
extinctions
0
600
400
200
0
Millions of years ago
FIG. 11.4
21. What do the five steepest peaks in Figure 11.4 represent?
23. According to Figure 11.4, when did the five largest mass extinction events occur?
24. What theory has been used to explain the pattern of rapid evolution that often occurs
after a mass extinction event, which is followed by long periods of stability?
25. Explain why mass extinction events are a significant part of the history of life on Earth.
224
Chapter Test B
Assessment Book
McDougal Littell Biology
Copyright © McDougal Littell/Houghton Mifflin Company.
22. What causes mass extinctions?