ap bio chapter 24 ap classroom
Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6. (b) How can the Hardy-Weinberg principle of genetic equilibrium be used to determine whether this population is evolving?
-Allelic frequency changes or five conditions that do not change if population is not evolving -Means of measurement/detection
Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6. (c) Identify a particular environmental change and describe how it might alter allelic frequencies in this population. Explain which condition of the Hardy-Weinberg principle would not be met.
-Environmental change identified -Explanation of how allelic frequency changed -Which Hardy-Weinberg condition not met
The fossil record indicates that in some cases reasonably well-defined species appear suddenly and remain unchanged for a long time before they become extinct. This phenomenon is referred to as a) allopatric speciation b) sympatric speciation c) phyletic gradualism d) punctuated equilibrium e) parallel evolution
d) punctuated equilibrium
a small number of lizards from a mainland population have been deposited on four isolated islands because of the effects of a rare strong storm. which of the following best predicts the outcome of these lizards reproducing for many generations on the islands? a) courtship rituals specific to each island lizard species prevent the lizards from interbreeding b) speciation results from bottleneck events that happened before the ancestoral species reached the islands c) the different species that currently exist are the result of hybridization between lizards from different islands d) the isolation prevents gene flow; thus, the lizards on different islands experience prezygotic isolation
d) the isolation prevents gene flow; thus, the lizards on different islands experience prezygotic isolation the primary cause of speciation is the prevention of gene flow between different populations. in this case, the original lizard populations were geographically isolated because they were on different islands, which prevented migration. Each island's Anolis species radiated from a similar-appearing common ancestor that underwent speciation in isolation.
For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law. What is the frequency of the recessive allele? a) √0.75 b) 0.75 c) √0.50 d) √0.25 e) 0.25
d) √0.25
The condition in which there are barriers to successful interbreeding between individuals of different species in the same community is referred to as a) latent variations b) sterility c) structural differences d) geographic isolation e) reproductive isolation
e) reproductive isolation
Scientists are studying several populations of finches on neighboring islands in the South Pacific. Previous genetic analysis has shown that a single gene controls tail-feather length in the finch populations and that the allele for long tail feathers (L) is dominant to the allele for short tail feathers (l). On two separate islands, the scientists recorded the number of finches with long tail feathers and the number of finches with short tail feathers. The results are shown in the table below. If the two finch populations are each in Hardy-Weinberg equilibrium and are isolated from each other, then which of the following graphs correctly displays the relative genotype frequencies?
C
Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6. (a) What is the frequency of each genotype (AA,Aa,aa) in this population? What is the frequency of thedominant phenotype?
Frequency AA = .36 · Frequency Aa = .48 · Frequency aa = .16 · Frequency dominant phenotype = .84
Female European corn borer moths (Ostrinia nubilalis) produce the sex pheromone 11−tetradecenyl acetate (11−TDA), which attracts males of their species. 11−TDA can be produced in two forms, E and Z, each with a different three-dimensional shape. Researchers have discovered two different strains of the European corn borer moth living in the same area. Females of the E strain produce primarily the E form of 11−TDA and females of the Z strain produce primarily the Z form of 11−TDA. Males of both strains are more attracted to the form of 11−TDA produced by the females of the same strain. Which of the following best predicts a long-term effect of the differences between the E and Z strains? a) the difference between the forms of the sex pheromone 11-TDA produced by E and Z strains will act as a prezygotic reproductive barrier leading to sympatric speciation b) The difference between the forms of the sex pheromone 11−TDA produced by E and Z strains will act as a postzygotic reproductive barrier, leading to allopatric speciation. c) Since the E and Z strains are both part of the same species, they will produce fertile offspring, leading to a single strain that produces both forms of 11−TDA. d) Since the E and Z strains are found in the same geographic area, they will hybridize, leading to a single strain that produces the dominant form of 11−TDA
a) the difference between the forms of the sex pheromone 11-TDA produced by E and Z strains will act as a prezygotic reproductive barrier leading to sympatric speciation There are many different mechanisms that can provide reproductive isolation within a population leading to speciation without a geographic barrier. Barriers that prevent fertilization are called prezygotic barriers and those that act after fertilization are called postzygotic barriers. Sex pheromone preferences affecting mate choice would reduce the likelihood of mating between members of the EE and ZZ European corn borer strains, acting as a prezygotic barrier by preventing mating that could lead to fertilization. Speciation that occurs without geographic isolation is called sympatric speciation.
For following group of questions first study the description of the situation and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet. A survey reveals that 25 percent of a population of 1,000 individuals have attached earlobes (are homozygous recessivefor the trait). For the following questions, assume that the population fits the parameters of the Hardy-Weinberg law. Unlike most natural populations, this population is best characterized in which of the following ways? a) there is a genetic equilibrium b) there is gene flow c) there is genetic drift d) mutations occur e) mating is nonrandom
a) there is a genetic equilibrium
A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what was the frequency of allele G in the gray moths that emerged in 1980? a) 0.33 b) 0.50 c) 0.67 d) 0.75 e) 1.00
b) 0.50
A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of moths in the natural population was white in 1962? a) 2% b) 4% c) 8% d) 20% e) 64%
b) 4%
On a large volcanic island, researchers are studying a population of annual herbaceous plants. Which of the following observations best supports the prediction that speciation will occur within the existing plant population? a) Individuals of the species sometimes reproduce asexually by producing runners. b) Lava has separated the population into two areas: an upland forest and a lowland marsh. c) Multiple groups of birds depend on the fruit produced by the plants as a source of food. d) The plants produce more seeds during warm summers than they do during cool summers.
b) Lava has separated the population into two areas: an upland forest and a lowland marsh.
The appearance of a fertile, polyploid individual within a population of diploid organisms is a possible source of a new species. If this individual is capable of reproducing to form a new population, scientists would consider this to be an example of a) allopatric speciation b) sympatric speciation c) polygenic inheritance d) genetic drift e) Hardy-Weinberg equilibrium
b) sympatric speciation
Gaucher disease type 1 (GD1) is a recessive genetic disease that affects 1 in 900 individuals in a particular population. GD1 is caused by a mutation in the enzyme glucocerebrosidase. Assuming the population is in Hardy-Weinberg equilibrium, calculate the frequency of the wild-type (nonmutant) allele for the enzyme glucocerebrosidase. a) 0.001 b) 0.033 c) 0.967 d) 0.999
c) 0.967 Assuming the population is in Hardy-Weinberg equilibrium, the frequency of the dominant wild-type allele can be determined from the Hardy-Weinberg equation p2+2pq+q2=1, where p represents is the frequency of the dominant allele, q is the frequency of the recessive allele and p+q=1. Since GD1 is a recessive condition, and it affects 1 in 900 individuals in the population, q2=1/900=0.001Therefore, q=q2−−√=1900−−−√=1/30=0.033. Since p+q=1, p=1−q, the frequency of the dominant wild-type allele p=1−0.033=0.967
All of the following are examples of prezygotic genetic isolating mechanisms EXCEPT: a) Male fireflies of different species have differing flash patterns. b) Three closely related orchid species flower on different days. c) The progeny of a cross between two different lizard species fail to develop properly. d) One species of snake lives in water and another is terrestrial. e) Peeper frogs mate in April, and tree frogs mate in June.
c) The progeny of a cross between two different lizard species fail to develop properly.
In eastern gray squirrels, Sciurus carolinensis, the allele for black fur (B) is dominant to the allele for gray fur (b). In a particular population of gray squirrels, 64% have black fur and 36% have gray fur. A researcher calculated the allelic frequencies to be B=0.4 and b=0.6. Five years later, the researcher returned to the location and determined the allelic frequencies within the squirrel population to be B=0.6 and b=0.4. Which of the following could best explain the increase in the frequency of the B allele in the population after five years? a) the frequency of the B allele increased because it is the dominant allele b) the frequency of the B allele is increased because squirrels with gray fur exhibit greater fitness c) the frequency on the B allele increased due to the selective pressures of the environment d) the frequency of the B allele increased because black squirrels randomly mate with other eastern gray squirrels
c) the frequency on the B allele increased due to the selective pressures of the environment It is most likely that the squirrels with black fur had a selective advantage, as the frequency of the allele for black fur increased.
A scientist is studying a population of lizards with three different color phenotypes. The color phenotype is controlled by a single gene with two alleles: an incompletely dominant allele A and a recessive allele a. The scientist collected data on the color of 100 lizards. The data are shown in the table. RED AA 75 PURPLE Aa 15 BLUE aa 10 To test the hypothesis that the population is at Hardy-Weinberg equilibrium, the scientist performed a chi-square test. Which of the following values is closest to the chi-square value the scientist calculated? a) 0.1 b) 1.9 c) 18.3 d) 23.1
d) 23.1 This choice correctly approximates the chi-square value from the data.
A moth's color is controlled by two alleles, G and g, at a single locus. G (gray) is dominant to g (white). A large population of moths was studied, and the frequency of the G allele in the population over time was documented, as shown in the figure below. In 1980 a random sample of 2,000 pupae was collected and moths were allowed to emerge. Assuming that the population was in Hardy-Weinberg equilibrium for the G locus, what percentage of the gray moths that emerged in 1980 was heterozygous? a) 0% b) 25% c) 33% d) 67% e) 100%
d) 67%
Which of the following statements best expresses the concept of punctuated equilibrium? a) Small variations gradually accumulate in evolving lineages over periods of millions of years. b) Random mating ensures that the proportions of genotypes in a population remain unchanged from generation to generation. c) Stability is achieved when selection favors the heterozygote, while both types of homozygotes are at a relative disadvantage. d) Evolutionary changes consist of rapid bursts of speciation alternating with long periods in which species remain essentially unmodified. e) Under competition for identical resources, one of the two competing species will be eliminated or excluded.
d) Evolutionary changes consist of rapid bursts of speciation alternating with long periods in which species remain essentially unmodified.
Figure 1 compares two models of speciation, A and B. Which of the following best explains how the ecological conditions are likely to be different in the two models? a) In model A the ecological conditions remain unchanged for long periods of time and then change drastically; in model B the ecological conditions change drastically from generation to generation. b) In model A the ecological conditions remain unchanged; in model B the ecological conditions change gradually over long periods of time. c) In model A the ecological conditions are changing drastically from generation to generation; in model B the ecological conditions remain unchanged. d) In model A the ecological conditions change gradually over a long period of time; in model B the ecological conditions remain unchanged for long periods of time and then change drastically.
d) In model A the ecological conditions change gradually over a long period of time; in model B the ecological conditions remain unchanged for long periods of time and then change drastically. Model A reflects gradualism while model B reflects punctuated equilibrium.
Goats and sheep belong to the same family but different genera. While they often live together in the same pastures, the hybrid offspring that are occasionally produced between the two species rarely survive. When such a hybrid does survive, it is usually sterile. Which of the following best explains the mechanism that maintains reproductive isolation between goats and sheep? a) Gene flow is prevented because the two species belong to different trophic levels and therefore do not share a food source. b) Habitat isolation creates a prezygotic barrier between the two species. c) The males of one species and the females of the other species are fertile at different times. d) The two species have a different number of chromosomes, resulting in a postzygotic barrier.
d) The two species have a different number of chromosomes, resulting in a postzygotic barrier. Closely related species might be able to mate and even produce a viable offspring, but if the chromosome numbers of the two species are not the same, the offspring will not have homologous pairs of chromosomes and will not be able to produce functional gametes.
