1. Methicillin-resistant Staphylococcus aureus is a bacterium that causes staph infections in hospitals. How do bacteria gain resistance to an antibiotic?
Treatment with an antibiotic causes the bacteria to mutate to adapt to the antibiotic.
The antibiotic stimulates the growth of bacterial cells.
Some of the bacteria already have a mutation that confers resistance to the antibiotic, allowing them to survive and pass on the advantageous gene to their offspring.
The hospital environment causes the bacteria to mutate.
Question 15-1
Answer: 3
Diff: Hard
Text Ref: Chapter 15 Case Study
Skill: Application
Also relates to: Chapter 14
Notes:
This question picks up where Chapter 14 leaves off and emphasizes the importance of variation to the process of natural selection. Emphasize how mutations are already present in a population prior to a change in the environment. Many students think the environment causes the mutation.
This question can also be used in Section 15.2.

2. Methicillin-resistant Staphylococcus aureus is a bacterium that causes staph infections in hospitals. How do bacteria gain resistance to an antibiotic?
Treatment with an antibiotic causes the bacteria to mutate to adapt to the antibiotic.
The antibiotic stimulates the growth of bacterial cells.
Some of the bacteria already have a mutation that confers resistance to the antibiotic, allowing them to survive and pass on the advantageous gene to their offspring.
The hospital environment causes the bacteria to mutate.

3. A species and its interaction with its environment
What is a population?
A species and its interaction with its environment
The biotic and abiotic components of an ecosystem
An individual organism and its niche
A group of interbreeding individuals that live in the same place at the same time and have the capacity to produce fertile offspring
Question 15-2
Answer: 4
Diff: Easy
Text Ref: 15.1
Skill: Factual
Also relates to: Chapters 1 & 26
Notes:
Because evolution occurs on populations, this question is used to review the definition of the term “evolution.”

4. A species and its interaction with its environment
What is a population?
A species and its interaction with its environment
The biotic and abiotic components of an ecosystem
An individual organism and its niche
A group of interbreeding individuals that live in the same place at the same time and have the capacity to produce fertile offspring
Question 15-2

5. Order the following from largest to smallest in size:
Gene, chromosome, nucleotide, DNA
Nucleotide, DNA, gene, chromosome
Chromosome, gene, DNA, nucleotide
DNA, chromosome, nucleotide, gene
Gene, nucleotide, DNA, chromosome
Question 15-3
Answer: 3
Diff: Moderate
Text Ref: 15.1
Skill: Factual
Also relates to: Chapters 9 & 12
Notes:
This question is a review of terms from earlier chapters. A firm grasp of genetics is required to understand the process of evolution.

6. Order the following from largest to smallest in size:
Gene, chromosome, nucleotide, DNA
Nucleotide, DNA, gene, chromosome
Chromosome, gene, DNA, nucleotide
DNA, chromosome, nucleotide, gene
Gene, nucleotide, gene, chromosome
Question 15-3

7. As identical genotypes As different phenotypes As identical traits
How might different versions of the same gene (alleles) be expressed at the level of the organism?
As identical genotypes
As different phenotypes
As identical traits
As chromatin or a chromosome
Question 15-4
Answer: 2
Diff: Moderate
Text Ref: 15.1
Skill: Conceptual
Also relates to: Chapters 9 & 12
Notes:
Students should remember that genotypes are the alleles and that phenotypes are the expression of the alleles as traits.

8. How might different versions of the same gene (alleles) be expressed at the level of the organism?
As identical genotypes
As different phenotypes
As identical traits
As chromatin or a chromosome

9. In betta fish, a single tail is dominant and a double tail is recessive. In a population of 200 betta fish, 25 fish have a double tail. What is the recessive allele frequency?
12.5%
25%
50%
65%
75%
Question 15-5
Answer: 2
Diff: Hard
Text Ref: 15.2
Skill: Application
Also relates to: Chapter 12
Notes:
Students should remember that each phenotype consists of two alleles. If 25 fish have a double tail (that is, are homozygous recessive), then there are 50 alleles for double tail. To determine the allele frequency for double tail, you divide 50/200 and get 0.25, or 25%, for the allele frequency within the population.

10. In betta fish, a single tail is dominant and a double tail is recessive. In a population of 200 betta fish, 25 fish have a double tail. What is the recessive allele frequency?
12.5%
25%
50%
65%
75%
Question 15-5

11. Evolutionary change occurs in association with all of the following except:
Mutations.
Gene flow.
Small population size.
Random mating.
Natural selection.
Question 15-6
Answer: 4
Diff: Moderate
Text Ref: 15.1
Skill: Factual
Notes:
The conditions that cause a population to evolve can be difficult not only for students to remember but also to understand. It is important to go over these conditions so that students understand the impact of each one.
It is also important to discuss the fact that few populations experience equilibrium. This question is a good introduction to the rest of Chapter 15 and can help students understand the mechanisms of evolution.

12. Evolutionary change occurs in association with all of the following except:
Mutations.
Gene flow.
Small population size.
Random mating.
Natural selection.

13. Why are mutations significant to populations?
Mutations produce genetic variation in a population. If the environment changes, part of the population will likely survive.
Mutations prevent genetic variation in a population. If the environment changes, part of the population will likely survive.
Mutations select for the most beneficial trait. If the environment changes, part of the population will survive.
Mutations weed out the weakest individuals in a population.
Question 15-7
Answer: 1
Diff: Hard
Text Ref: 15.2
Skill: Conceptual
Also relates to: Chapter 14
Notes:
It is important for students to understand the impact that mutations have on a population, as mutations are are the basis of change. Students have a hard time understanding that mutations occur randomly and are already present when a change occurs in the environment. Many students think that mutations are produced by a change in the environment. This point must be made clear for students to understand the process in evolution.

14. Why are mutations significant to populations?
Mutations produce genetic variation in a population. If the environment changes, part of the population will likely survive.
Mutations prevent genetic variation in a population. If the environment changes, part of the population will likely survive.
Mutations select for the most beneficial trait. If the environment changes, part of the population will survive.
Mutations weed out the weakest individuals in a population.

15. Two populations of gorillas, one living in the mountains and one living in the valley, no longer mate or exchange alleles in their gene pools. What can happen?
With no gene flow, the two populations will remain identical to each other.
With no gene flow, the two populations may become so different that they become different species.
With no gene flow, each population will have an increased number of mutations.
With no gene flow, the two populations will express their alleles or show their traits differently.
Question 15-8
Answer: 2
Diff: Hard
Text Ref: 15.2
Skill: Conceptual
Also relates to: Chapter 16
Notes:
Students should realize that when members of a population become very different, they can become different species. This concept will be explored in greater detail in Chapter 16.

16. Two populations of gorillas, one living in the mountains and one living in the valley, no longer mate or exchange alleles in their gene pools. What can happen?
With no gene flow, the two populations will remain identical to each other.
With no gene flow, the two populations may become so different that they become different species.
With no gene flow, each population will have an increased number of mutations.
With no gene flow, the two populations will express their alleles or show their traits differently.

17. A small population will be left with more allele variations.
Why does genetic drift affect a small population more than it affects a large population?
A small population will be left with more allele variations.
A chance event is more likely to eliminate an allele from a small population, leaving it with reduced allelic variation.
Genetic drift always kills off small populations.
A small population will experience gene flow.
Question 15-9
Answer: 2
Diff: Moderate
Text Ref: 15.2
Skill: Conceptual
Notes:
This question is used to explain the impact of genetic drift on populations of different sizes. There is a greater chance that alleles can be eliminated by genetic drift when the population is small, reducing allelic variation.

18. Why does genetic drift affect a small population more than it affects a large population?
A small population will be left with more allele variations.
A chance event is more likely to eliminate an allele from a small population, leaving it with reduced allelic variation.
Genetic drift always kills off small populations.
A small population will experience gene flow.

19. They are from a small population. They are from a large population.
Why do many purebred German shepherds, golden retrievers, and Doberman pinschers have hip dysplasia and related joint disorders?
Breeding is random.
Breeding is not random.
They are from a small population.
They are from a large population.
They exhibit gene flow in a population.
Question 15-10
Answer: 2
Diff: Hard
Text Ref: 15.2
Skill: Application
Notes:
This question is used to explain why purebred dogs tend to have many more genetic disorders than do mutts, and why close relatives should not mate. Two related individuals are more likely than two unrelated individuals to carry the same genes for the same disorders.
It is interesting that two-thirds of all black standard poodles can be traced to Vancouver’s Wycliffe Kennel, due to non-random mating.

20. Why do many purebred German shepherds, golden retrievers, and Doberman pinschers have hip dysplasia and related joint disorders?
Breeding is random.
Breeding is not random.
They are from a small population.
They are from a large population.
They exhibit gene flow in a population.

21. Why is natural selection also called “survival of the fittest”?
The strongest organisms will always survive.
Those organisms with the most advantageous traits must mate.
Individuals with advantageous traits survive to pass the traits on to their offspring.
There is an origin of the species.
Question 15-11
Answer: 3
Diff: Hard
Text Ref: 15.3
Skill: Conceptual
Notes:
Although students have heard the phrase “survival of the fittest,” most students do not know its meaning. When you tie in the meaning of fitness with natural selection, students have a “light bulb” moment, and the importance of reproduction in natural selection process sticks with them.

22. Why is natural selection also called “survival of the fittest”?
The strongest organisms will always survive.
Those organisms with the most advantageous traits must mate.
Individuals with advantageous traits survive to pass the traits on to their offspring.
There is an origin of the species.

23. Newts of the genus Taricha are poisonous, deterring their predators from eating them. The common garter snake, a predator, has evolved a resistance to the newt toxins. This situation is an example of:
Competition
Natural selection
Artificial selection
Sexual selection
Coevolution
Question 15-12
Answer: 5
Diff: Moderate
Text Ref: 15.3
Skill: Application
Also relates to: Chapter 27
Notes:
Students will learn more about how organisms exercise selective pressure on one another when they discuss community interactions in Chapter 27, but this is an important concept to understand now regarding evolution.

24. Newts of the genus Taricha are poisonous, deterring their predators from eating them. The common garter snake, a predator, has evolved a resistance to the newt toxins. This situation is an example of:
Competition
Natural selection
Artificial selection
Sexual selection
Coevolution

25. Directional selection Stabilizing selection Disruptive selection
A farmer uses insecticide but still gets crop damage. Many of the targeted insects developed insecticide resistance. What mode of natural selection has occurred?
Directional selection
Stabilizing selection
Disruptive selection
Artificial selection
Coevolution
Question 15-13
Answer: 1
Diff: Moderate
Text Ref: 15.3
Skill: Application
Notes:
This question shows students that natural selection can favor populations in different ways.

26. A farmer uses insecticide but still gets crop damage
A farmer uses insecticide but still gets crop damage. Many of the targeted insects developed insecticide resistance. What mode of natural selection has occurred?
Directional selection
Stabilizing selection
Disruptive selection
Artificial selection
Coevolution

27. Question 15-13

28. In an island population of birds, the large birds eat the only seeds available, which are large, and the small birds feed on flower nectar. The medium-sized birds have a hard time eating both the seeds and the nectar. What mode of natural selection has occurred?
Directional selection
Stabilizing selection
Disruptive selection
Artificial selection
Coevolution
Question 15-14
Answer: 3
Diff: Moderate
Text Ref: 15.3
Skill: Application
Notes:
This question shows students that natural selection can favor populations in different ways.

29. In an island population of birds, the large birds eat the only seeds available, which are large, and the small birds feed on flower nectar. The medium-sized birds have a hard time eating both the seeds and the nectar. What mode of natural selection has occurred?
Directional selection
Stabilizing selection
Disruptive selection
Artificial selection
Coevolution

30. One allele encodes for normal hemoglobin, forming biconcave red blood cells; another allele encodes for defective hemoglobin, forming irregularly shaped red blood cells that cause sickle-cell anemia. What is the benefit of having both alleles in a population?
Through natural selection, individuals with the sickle-cell allele will be removed from the gene pool.
The different phenotypes produced are favored under different environmental conditions.
Individuals with the sickle-cell allele enjoy an increased fitness.
They provide variation in the population.
Question 15-15
Answer: 2
Diff: Hard
Text Ref: 15.3
Skill: Application
Notes:
This is a strong way to end the chapter, putting together the value of variation and the natural selection process. This example helps students understand why some alleles, which can be unfavorable, remain in a population: These alleles are beneficial in certain situations, as is the sickle-cell allele (in areas where malaria is prevalent).

31. One allele encodes for normal hemoglobin, forming biconcave red blood cells; another allele encodes for defective hemoglobin, forming irregularly shaped red blood cells that cause sickle-cell anemia. What is the benefit of having both alleles in a population?
Through natural selection, individuals with the sickle-cell allele will be removed from the gene pool.
The different phenotypes produced are favored under different environmental conditions.
Individuals with the sickle-cell allele enjoy an increased fitness.
They provide variation in the population.

32. Suppose that 16% of a population exhibits a recessive phenotype
Suppose that 16% of a population exhibits a recessive phenotype. What does this 16%, as a decimal, represent in the Hardy-Weinberg equation? p2
2pq q2 p q
Question 15-16
Answer: 3
Diff: Moderate
Text Ref: A Closer Look
Skill: Application
Notes:
If you go into the Hardy-Weinberg principle in greater detail, this question can help students understand all of the parts of the equation.

33. Suppose that 16% of a population exhibits a recessive phenotype
Suppose that 16% of a population exhibits a recessive phenotype. What does this 16%, as a decimal, represent in the Hardy-Weinberg equation? p2
2pq q2 p q

34. If q2 = 0.16 for a population, then we can rearrange the equation ___________ to solve for p.
p2 + 2pq + q2 = 1
p + q = 1
Question 15-17
Answer: 2
Diff: Easy
Text Ref: A Closer Look
Skill: Application
Notes:
We know that q2 = If we know q2, we can solve for q = √0.16, so q = This means that p = 1 – q. We plug in 0.4 for q and get p = 1 – 0.4, so p = 0.6.

35. If q2 = 0.16 for a population, then we can rearrange the equation ___________ to solve for p.
p2 + 2pq + q2 = 1
p+q = 1

36. If q = 0.4 and p = 0.6 for a population, then 2pq = _____.
0.8
0.24
0.32
0.36
0.48
0.56
0.78
Question 15-18
Answer: 6
Diff: Easy
Text Ref: A Closer Look
Skill: Application
Notes:
2pq = (2) x (0.6) x (0.4) = 0.48.
In addition, if we know p, then we can figure out p2: p2 = p x p, which means p2 = 0.6 x 0.6, so p2 =

37. If q = 0.4 and p = 0.6 for a population, then 2pq = _____.
0.8
0.24
0.32
0.36
0.48
0.56
0.78

38. If q = 0.4, p = 0.6, and 2pq = 0.48 for a population, then both Hardy-Weinberg equations must add up to ____. 1 2 3 4 5 6 7 8
Question 15-19
Answer: 1
Diff: Easy
Text Ref: A Closer Look
Skill: Application
Notes:
Both Hardy-Weinberg equations should always add up to 1. Students can check their work by remembering this. Students often start out with the correct numbers but do the math incorrectly somewhere in the middle.

39. If q = 0.4, p = 0.6, and 2pq = 0.48 for a population, then both Hardy-Weinberg equations must add up to ____. 1 2 3 4 5 6 7 8