ch 21

58) Which of these is closest to the allele frequency in the founding population?

A) 0.1 a, 0.9 A

49) What proportion of the population is probably heterozygous ( Aa) for this trait?

A) 0.50

59) If one assumes that Hardy-Weinberg equilibrium applies to the population of colonists on this planet

A) 100

56) The sickle-cell allele is pleiotropic (i.e., it affects more than one phenotypic trait).

A) adaptations are often compromises.

25) How can gene flow improve adaptation of population?

A) beneficial alleles are transferred to a new population

28) Which of the following attributes has the least effect on the contribution an individual makes to the gene pool of the next generation?

A) camouflages from predators

19) Evolution

A) can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met.

57) In the United States, the parasite that causes malaria is not present,

A) directional selection; disruptive selection

18) In evolution, which driving factor most consistently requires a small population as a precondition for its occurrence?

A) genetic drift

10) In the formula for determining a population's genotype frequencies, the 2 in the term 2pq is necessary because

A) heterozygotes can come about in two ways.

27) What is the result of adaptive evolution?

A) increase in frequency of alleles that provide reproductive advantage

51) Which population is most likely to be subject to the bottleneck effect?

A) population A

32) Which of the following is most likely to produce an African butterfly species in the wild whose members have one pattern?

A) stabilizing selection

33) Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation?

A) stabilizing selection

67) Sparrows with average-sized wings survive severe storms better than those with longer or shorter wings, illustrating

A) stabilizing selection.

HIV's genome of RNA includes the code for reverse transcriptase (RT

A) using moderate doses of NA

53) Although selection is clearly present, if the ideal equilibrium of alleles existed, what should be the proportion of heterozygous individuals in populations that live here

A. 0.0455)

24) Which one of the genetic drift effects would limit natural selection?

A. alter frequencies in small population

9) Which process in sexual reproduction results in diversity at the nucleotide level?

A. chromosome crossover

Anopheles mosquitoes, which carry the malaria parasite, cannot live above elevations of 5,900 feet. In addition, oxygen availability decreases with higher altitude

A. graph with the decline

6) Why don't similar genotypes always produce the same phenotype? 6)

Animals display different phenotypes

70) A fruit fly population has a gene with two alleles, A1 and A2. Tests show that 70% of the gametes produced in the population contain the A1 allele.

B) 0.42

What is the estimated frequency of allele A in the gene pool?

B) 0.50

14) Which statement about variation is true?

B) All new alleles are the result of nucleotide variability.

26) What is true of natural selection?

B) Mutations occur at random

36) The same gene that causes various coat patterns in wild and domesticated cats also causes a cross-eyed condition in these cats

B) Phenotype is often the result of compromise.

35) In seedcracker finches from Cameroon, small- and large-billed birds specialize in cracking soft and hard seeds, respectively

B) directional selection

55) Considering the overall human population of the U.S

B) gene flow

11) In the formula for determining a population's genotype frequencies, the pq in the term 2pq is necessary because

B) heterozygotes have two alleles.

30) Sexual dimorphism is most often a result of

B) intersexual selection.

63) "Until the agricultural revolution 10,000 years ago, people used to live in small populations with little gene flow between them

B) no evolution.

50) In which population would it be least likely that an accident would significantly alter the frequency of the brown allele?

B) population B

8) Whenever diploid populations are in Hardy-Weinberg equilibrium at a particular locus,

B) the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change.

52) With respect to the sickle - cell allele, what should be true of the fi hemoglobin locus in U.S. populations of African - Americans whose ancestors were from equatorial Africa? 1. The average heterozygosity at this locus should be decreasing over time. 2. There is an increasing heterozygote advantage at this locus. 3. Diploidy is helping to preserve the sickle-cell allele at this locus. 4. Frequency-dependent selection is helping to preserve the sickle-cell allele at this locus.

B. 1 and 3

The frequency of individuals born in a population with PKU is q2. There is one PKU ( q2) birth per 10,000 births

B. 2%

1) If, on average, 46% of the loci in a species' gene pool are heterozygous, then the average homozygosity of the species should be

B. 54%

7) Which of the following describes a mechanism for generating more genes? 7)

B. duplication

Blue light is a portion of the visible spectrum that penetrates deep into bodies of water. Ultraviolet (UV) light, though, can penetrate even deeper.

B. grafh B with the X and blue on top of UV

62) Swine are vulnerable to infection by bird flu virus and human flu virus

C) If the Tamiflu-resistance gene involves a cost,

3) Which of the following is a true statement concerning genetic variation? 3)

C) It must be present in a population before natural selection can act upon the population.

37) Identify the statement that describes the imperfection of natural

C) Natural selection is generally limited to modifying structures that were present in previous generations and in previous species.

45) Every HIV particle contains two RNA molecules

C) One of the RNA molecules has experienced gene duplication

46) In a hypothetical population's gene pool, an autosomal gene, which had previously been fixed,

C) The proportion of the population that is hetro

47) What is the most reasonable conclusion that can be drawn from the fact that the frequency of the recessive trait ( aa) has not changed over time?

C) The two phenotypes are about equally adaptive under laboratory conditions

63) "Until the agricultural revolution 10,000 years ago, people used to live in small populations with little gene flow between them.

C) adaptive evolution.

61) You are maintaining a small population of fruit flies

C) cross your flies with flies from another lab

21) If the original finches that had been blown over to the Galápagos Islands from South America

C) genetic drift and the founder effect.

65) Natural selection changes allele frequencies because some survive and reproduce more successfully than others

C) individuals

43) Examining the figure, which type of selection eliminates extreme frequency of individuals' phenotype?

C) stabilizing selection

66) No two people are genetically identical, except for identical twins. The main source of genetic variation among human individuals is

C) the reshuffling of alleles in sexual reproduction.

53) Although selection is clearly present, if the ideal equilibrium of alleles existed, what should be the proportion of heterozygous individuals in populations that live here?

C. 0.32

13) In peas, a gene controls flower color such that R = purple and r = white.

C. 0.80

Soon after the island of Hawaii rose above the sea surface (somewhat less than 1 million years ago), the evolution of life on this new island should have been most strongly influenced by

C. founder effect

2) Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?

D) Each bird's survival was strongly influenced by the depth and strength of its beak as the drought persisted.

22) Which of the following statements best summarizes evolution as it is viewed today?

D) It is the differential survival and reproduction of the most-fit phenotypes.

42) Examining the figure, which type of selection has two peaks of frequency of individuals?

D) disruptive selection

15) What is a population in biology?

D) an assessment of evolution at a particular locus

16) What is the Hardy-Weinberg equation?

D) an assessment of evolution at a particular locus

4) How did Mendel's model of inheritance help explain Darwin's theory of natural selection?

D) by proposing mechanism of how organisms transmit discrete heritable units

5) How can genetic variation at the whole gene level ( gene variability ) be quantified?

D) by the average percentage of loci that are heterozygous

29) The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes

D) frequency-dependent selection.

20) Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing

D) gene flow.

68) If the nucleotide variability of a locus equals 0%, what is the gene variability and number of alleles at that locus?

D) gene variability = 0%; number of alleles = 1

60) If four of the original colonists died before they produced offspring,

D) genetic drift.

69) There are 25 individuals in population 1, all with genotype AA , and there are 40 individuals

D) genetic drift.

31) Adult male humans generally have deeper voices than do adult female humans,

D) sexual dimorphism was developing over time in these species.

23) What is the founder effect

D) when a few individuals become isolated from a larger population, and their gene pool differs from that source population

In a very large population, a quantitative trait has the distribution pattern shown in Figure 21.3. If the curve in Figure 21.3 shifts to the left or to the right 1. immigration or emigration 2. directional selection 3. adaptation 4. genetic drift 5. disruptive selection

E) 2 and 342) Examining the figure, which type of selection has two peaks of frequency of individuals? 42)

34) Heterozygote advantage should be most closely linked to which of the following?

E) stabilizing selection

12) In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the frequency of individuals that are homozygous for this allele

c. 0.09