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2023-mcq-5

By j l
Last updated about 2 years ago
111 Questions

The diploid number of chromosomes in the cell of a domesticated dog is 78. Which of the following options includes the correct number of chromosomes in a cell after each cellular process (G2 checkpoint, meiosis, and fertilization, respectively)?

Humans have a diploid number (2n) of 46. Which of the following statements best predicts the consequence if meiosis did not occur during gametogenesis?

If 2n = 48 for a particular cell, then the chromosome number in each cell after meiosis would be

Which of the following best describes the cells that result from the process of meiosis in mammals?

All of the following are true statements about meiosis in mammals EXCEPT:

Table 1 shows the stage and number of cells and chromosomes per cell at the end of the stage in a 2n=24 organism.
Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis â… ?

Both mitosis and meiosis begin with a parent cell that is diploid. Which of the following best describes how mitosis and meiosis result in daughter cells with different numbers of chromosomes?

Which of the following occurs during mitosis but not during meiosis I ?

Saccharomyces cerevisiae is a diploid yeast species that can reproduce either sexually or asexually. An experiment was performed to induce mitotically dividing S. cerevisiae cells in G2 to undergo meiosis. Which of the following best describes the steps these cells will follow to form gametes?

Which of the following best describes the cellular process illustrated in Figure 1 ?

Within a forest ecosystem, there is a large amount of diversity among members of a warbler species. Of the following stages of meiosis illustrated for a typical cell, which contributes most to diversity among the warblers?

In most vertebrates, the sperm cell normally contributes which of the following to the new organism?

During prophase â…  replicated homologous chromosomes pair up and undergo synapsis. What testable question is generated regarding synapsis and genetic variability by Figure 1 ?

Scientists have found that DNA methylation suppresses crossing-over in the fungus Ascobolus immersus. Which of the following questions is most appropriately raised by this specific observation?

The diagram above illustrates which of the following processes?

The events listed below generally take place during meiosis.
I. Synapsis occurs.
II. Crossing-over is completed.
III. Condensation of chromosomes begins.
IV. Separation of homologous chromosomes begins.
Which of the following is the correct sequence of these events?

A model showing two possible arrangements of chromosomes during meiosis is shown in Figure 1.
Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1 ?

The process depicted in the image above is best summarized by which of the following descriptions?

Which of the following best explains why triploid bananas do not produce seeds?

• Directions: Each group of questions below concerns an experimental or laboratory situation or data. In each case, first study the description of the situation or data. Then choose the one best answer to each question following it.
Achondroplastic dwarfism is a dominant genetic trait that causes severe malformation of the skeleton. Homozygotes for this condition are spontaneously aborted (hence, the homozygous condition is lethal) but heterozygotes will develop to be dwarfed.
Matthew has a family history of the condition, although he does not express the trait. Jane is an achondroplastic dwarf.Matthew and Jane are planning a family of several children and want to know the chances of producing a child with
achondroplastic dwarfism.

The genotypes of Matthew and Jane are best represented as

The probability that Matthew and Jane’s first child will be an achondroplastic dwarf is

If three children are born to Matthew and Jane, what are the chances that the first two children will not express the
trait but that the third child will be an achondroplastic dwarf?

Directions: Each group of questions below concerns an experimental or a laboratory situation. In each case, first study the description of the situation. Then choose the one best answer to each question following it.
In dogs, one pair of alleles determines coat color (dark and albino). Another pair of alleles determines hair length (short and long). Thus, each gamete will contain one of the coat-color alleles, C or c and one of the hair-length alleles, B or b. In repeated crosses of a specific dark, short-haired dog with an albino, long-haired dog, all the offspring were dark with short hair, as shown in cross I. However, in subsequent crosses of another dark, short-haired dog with a dark, long-haired dog, the ratios shown in cross II below were obtained.

In cross II, the genotype of the dark, short-haired parent is

Which of the following is probably the genotype of the dark, short-haired parent in cross I?

Which of the following correctly describes the relationship of the dark-coat-color allele to the albino condition?

Friedreich’s ataxia is an inherited disorder. Friedreich’s ataxia is caused by an insertion mutation in a noncoding portion of the FXN gene where a GAA
triplet is repeated hundreds of times. The FXN gene encodes the protein frataxin. A pedigree of a family with members affected by this disorder is shown in Figure 1.
A researcher collected DNA from several members of the family and used PCR to amplify the FXN genes from each individual’s DNA. The researcher then used DNA gel electrophoresis to separate the DNA. The results are shown in Figure 2.
The researcher also used a computer to model the structure of the mutant FXN allele. The model suggests that the repeated GAA triplets in the mutant FXN gene may lead to the formation of an unusual triple-stranded configuration of DNA (Figure 3).

Based on the data in Figure 1, which of the following best describes the inheritance pattern of Friedreich’s ataxia?

The probability that individual Ⅲ-5 will develop Friedreich’s ataxia is closest to which of the following?

A blue-flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. These seeds germinate and grow into flowering plants. Of these plants, 36 produce blue flowers and 14 produce pink flowers. What is the best explanation for the pink-flowered offspring?

Table I shows the results of breeding experiments to examine the inheritance of flower color (purple versus white) and pod shape (inflated versus constricted). For the crosses recorded in Table I, true-breeding parents were crossed to produce
F1 offspring, which were then testcrossed to homozygous recessive individuals. Table II shows the results of computer-simulated crosses to model the inheritance of leaf shape (broad versus narrow) and flower color (purple versus white).

Based on the data in Table I, which of the following best explains why there are no individuals with constricted
pods in the F1 generation?

In Table I, the ratio of phenotypes in the offspring from the testcross with F1 plants that had purple flowers and
inflated pods suggests that the genes for flower color and pod shape are located (A) close together on the same autosome

Which of the following provides the best justification for an assumption that might have been used in the computer simulation (Table II)?

In Table II, the F1 offspring of the cross between broad-leaved, white-flowered plants with narrow-leaved, purple-flowered plants have a phenotype that differs from that of either parent. However, many testcross offspring have the same phenotype as one of the two plants in the parental cross, but relatively few testcross offspring have the same phenotype as the F1 offspring. Which of the following best explains the observation?

In pea plants, flower color and the length of the flower’s pollen grains are genetically determined. Researchers studying pea plants crossed homozygous dominant pea plants with homozygous recessive pea plants. The F1 plants were then crossed, and the number of offspring with each phenotype was recorded. The researchers’ observed data,however, differed from the expected data. The researchers did a chi-square analysis and calculated the chi-square value to be5.5.
Based on their calculation, the researchers would most likely conclude which of the following?

In a certain type of chicken, the allele for gray feathers is recessive to the allele for black feathers, and the allele for a spotted pattern is recessive to the allele for a solid pattern. Chickens that are heterozygous for both traits were crossed and the phenotypes for the offspring were recorded (Table 1).
To determine whether the data are consistent with the expectations for independent assortment, students performed a chi-square analysis.
Which of the following is the closest to the calculated chi-square value for the experiment?

In fruit flies of the genus Drosophila, the allele for vestigial wings is recessive to the allele for round wings, and the allele for brown eye color is recessive to the allele for red eye color. A scientist crossed flies that are heterozygous for both traits and determined the number of offspring with each combination of phenotypes. The scientist performed a chi-square analysis to determine if the data are consistent with the expectations for independent assortment. The chi-square calculated value for the experiment was 6.03.
Based on the chi-square calculated value, which of the following statements is most accurate?

researcher hypothesizes that, in mice, two autosomal dominant traits, trait Q and trait R, are determined by separate genes found on the same chromosome. The researcher crosses mice that are heterozygous for both traits and counts the number of offspring with each combination of phenotypes. The total number of offspring producedwas 64. The researcher plans to do a chi-square analysis of the data and calculates the expected number of mice
with each combination of phenotypes. Which of the following is the expected number of offspring that will display both trait Q and trait R?

Dystrophin is a protein that is expressed in certain muscle cells. In combination with other cellular proteins, dystrophin strengthens protein fibers in muscle cells to allow muscles to contract without injury.
Nucleotide deletions in the gene that encodes dystrophin are associated with the genetic disorder Duchenne Muscular Dystrophy (DMD). Individuals with DMDdo not produce functional dystrophin and, as a result, the protein fibers, andthen entire muscle cells, become damaged.
The history of DMD for three generations of a family is shown in Figure 1.
Individuals Ⅲ-1 and Ⅲ-2 plan to have children and wish to first determine whether individual Ⅲ-2 is a carrier of DMD. Individual Ⅲ-2 undergoes genetic testing to determine whether individual Ⅲ-2 carries a particular allele for themutated dystrophin that is associated with the disorder in this family. The results of gel electrophoresis analysis of the individual’s dystrophin alleles and the alleles of several family members are shown in Figure 2.

Based on the information provided in Figures 1 and 2, which of the following best describes the chances of individuals and â…¢-1 and â…¢-2 passing on the mutant dystrophin allele and/or DMD disorder to their offspring?

Based on the information provided, which of the following describes the most likely pattern of inheritance for the disorder?

Eye color in a particular strain of fly is influenced by one gene with two alleles: a dominant allele that results in red eyes and a recessive allele that results in sepia eyes.
A red-eyed female from a true-breeding population is mated with a sepia-eyed male. The F1 offspring are all red-eyed. The F1 flies are allowed to interbreed, producing the following in the F2 generation.
Females: 40 red eyes; 13 sepia eyes
Males: 39 red eyes; 11 sepia eyes
Which of the following best describes the likely mode of inheritance for the eye-color gene?

Assume that genes A and B are not linked. If the probability of allele A in a gamete is 1/2 and the probability of allele B in a gamete is 1/2, then the probability that both A and B are in the same gamete is

In pea seeds, yellow color (Y) is dominant to green color (y), and a round shape (R) is dominant to a wrinkled shape (r). A dihybrid cross between a true-breeding plant with yellow, round seeds (YYRR) and a true-breeding plant with green, wrinkled seeds (yyrr) results in an F1 generation of plants with yellow, round seeds. Crossing two F1 plants produces an F2 generation with approximately nine times as many plants with yellow, round seeds as
plants with green, wrinkled seeds.
Which of the following best explains these results?

The Russian blue is a rare breed of cat that is susceptible to developing cataracts on the eyes. Scientists hypothesize that this condition is inherited as a result of a mutation. Figure 1 shows a pedigree obtained in a study of cats owned by members of the Russian Blue Club in Sweden.
Based on the inheritance pattern shown in Figure 1, which of the following best predicts the nature of the original mutation?

Insulin is a hormone produced by some pancreatic cells. Scientists have isolated the DNA sequence that codes for human insulin production.
Which of the following best predicts the effect of inserting this gene into the DNA of a bacterial cell?

In sweet pea plants, purple flower color is dominant over red flower color and long pollen grain shape is dominant over round pollen grain shape. Two sweet pea plants that are heterozygous for both flower color and pollen grain shape are crossed with one another. A geneticist is surprised to observe that there are far fewer round, purple offspring and long, red offspring than were predicted by the 9:3:3:1 expected phenotypic ratio.
Which of the following statements provides the most reasonable prediction to account for the deviation from the expected results?

Which of the following best supports the claim that organisms of different domains share a common ancestor?

For following group of questions first study the description of the situation and diagram and then choose the one best answer to each question following it and fill in the corresponding oval on the answer sheet.
The pedigree of a family with a history of a particular genetic disease is shown below. Squares represent males and circles represent females. Shaded symbols represent those who have the disease.

Which of the following is the most likely mode of inheritance for the disease?

If Individual 2 were to marry a woman with no family history of the disease, which of the following would most
likely be true of their children?

If Individual 6 marries a woman with the disease, what is the probability that their first child will have the disease?

In the following human pedigree, squares represent males, circles represent females, and shaded symbols indicate individuals affected with a disorder.
One of the affected males from the third generation has a child with a female who is a carrier. For the pedigree shown above, which of the following best expresses the probability that the couple’s first son will be affected with the disorder?

In the pedigree above, squares represent males and circles represent females. Individuals who express a particular trait are represented by shaded figures. Which of the following patterns of inheritance best explains the transmission of the trait?

• Directions: Each of the questions or incomplete statements below is followed by four suggested answers or completions. Select the one that is best in each case and then fill in the corresponding circle on the answer sheet.
The three-spined stickleback (Gasterosteus aculeatus) is a small fish found in both marine and freshwater environments.Marine stickleback populations consist mainly of individuals with armor-like plates covering most of their body surface (completely plated). Approximately 10,000 years ago, some marine sticklebacks colonized freshwater environments. After many generations in the freshwater environments, the freshwater stickleback populations lacked the armor plating
(low plated) typical of marine stickleback populations.
Over the period between 1957 and 2005, one freshwater population, in Lake Washington, a lake in a coastal region of the northwestern United States, changed from having a majority of individuals of the low-plated phenotype to having more individuals of the completely-plated phenotype than of the low-plated phenotype. Figure 1 shows the distribution of plated
phenotypes in Lake Washington sticklebacks at four time points between 1957 and 2005.
A single gene, ectodysplasin (EDA), is thought to be responsible for the variation in the number of armor plates in sticklebacks. Figure 2 shows a phylogenetic tree constructed by comparing DNA sequences of the EDA gene from a number of stickleback populations with low-plated or completely plated phenotypes. Figure 3 shows a phylogenetic tree constructed by comparing the sequences of 25 genes that were randomly selected from the same populations as shown in
Figure 2. In both figures, shaded populations display the completely plated phenotype.

A completely-plated stickleback from a marine population was mated to a low-plated stickleback from a freshwater
population. The resulting F1 hybrids all displayed a completely plated phenotype. When the F1 hybrids were
allowed to interbreed, the resulting F2 generation included completely plated offspring and low-plated offspring in
an approximate 3:1 ratio. Which of the following conclusions is best supported by the results of the breeding experiments?

A student crosses a pure-breeding line of red-flowered poinsettias with a pure-breeding line of white-flowered poinsettias. The student observes that all the plants in the F1 generation have pink flowers. The student then crosses the F1 plants with one another and records observations about the plants in the F2 generation. The student will use the F2 data to perform a chi-square goodness-of-fit test for a model of incomplete dominance. The setup for the
student’s chi-square goodness-of-fit test is presented in Table 1.
The critical value for a chi-square test with a significance level of p=0.05 and 2 degrees of freedom is 5.99.
Which of the following statements best completes the student’s chi-square goodness-of-fit test?

A researcher is crossing two organisms that are heterozygous for three Mendelian, unlinked traits (XxYyZz).
Which of the following is the fraction of offspring that are predicted to have the genotype xxyyzz?

A couple has 5 children, all sons. If the woman gives birth to a sixth child, what is the probability that the sixth child will be a son?

Directions: This group of questions consists of five lettered headings followed by a list of phrases or sentences. For each phrase or sentence, select the one heading to which it is most closely related. Each heading may be used once, more than once, or not at all.
This group of questions refers to the probabilities below.
Assume that the alleles referred to all assort independently.
(A) 0
(B) 1/16
(C) 1/4
(D) 1/2
(E) 3/4

Probability that the genotype Aa will be produced by the parents Aa x Aa

Probability that the genotype ccdd will be produced by the parents CcDd x CcDd

Probability that the genotype Rr will be produced by the parents Rr x rr

Probability that the genotype TTSs will be produced by the parents TTSs x TtSS

In fruit flies, purple eyes and ebony body are traits that display autosomal recessive patterns of inheritance. In a genetics experiment, students cross wild-type flies with flies that have purple eyes and ebony bodies. The students observe that all the flies in the F1 generation have normal eyes and a normal body color. The students then allow the F1 flies to mate and produce an F2 generation. The students record observations about the flies in the F2 generation and use the data to perform a chi-square goodness-of-fit test for a model of independent assortment. The setup for the students’ chi-square goodness-of-fit test is presented in Table 1.
The students choose a significance level of p=0.01. Which of the following statements best completes the next step of the chi-square goodness-of-fit test?

In garden peas, a single gene controls stem length. The recessive allele (t) produces short stems when homozygous. The dominant allele (T) produces long stems. A short-stemmed plant is crossed with a heterozygous long-stemmed plant. Which of the following represents the expected phenotypes of the offspring and the ratio in which they will occur?

Tay-Sachs disease is a rare inherited disorder caused by an autosomal recessive allele of the HEXA gene. Affected individuals exhibit severe neurological symptoms and do not survive to reproductive age. Individuals who inherit one copy of the allele (Tay-Sachs carriers) typically show no symptoms of the disorder. The frequencies of Tay-Sachs carriers
in the general population of North America and in three different subpopulations are presented in the table.

Which of the following pedigrees most accurately represents a family with a history of Tay-Sachs disease?

In a strain of tomato plants, short plant height and small fruit size are traits that display autosomal recessive patterns of inheritance. To investigate whether the traits segregate independently, researchers cross a pure-breeding line of tall tomato plants that have large fruits with a pure-breeding line of short tomato plants that have small fruits. The researchers observe that all the plants in the F1 generation are tall and have large fruits. The researchers cross the F1 plants with one another to generate an F2 generation. The researchers record observations for the F2 generation and will use the data to perform a chi-square goodness-of-fit test for a model of independent assortment. The setup for the chi-square goodness-of-fit test is shown in Table 1.
The researchers choose a significance level of p=0.05 . Which of the following best completes the chi-square goodness-of-fit test?

In peas the trait for tall plants is dominant (T) and the trait for short plants is recessive (t). The trait for yellow seed color is dominant (Y) and the trait for green seed color is recessive (y). A cross between two plants results in 296 tall yellow plants and 104 tall green plants. Which of the following are most likely to be the genotypes of the parents?

The data above represent the results of three different crosses involving the inheritance of a gene that determines hether a certain organism is blue or white. Which of the following best explains the mechanism of inheritance of the gene?

A gene that influences coat color in domestic cats is located on the X chromosome. A female cat that is heterozygous for the gene (XBXO) has a calico-colored coat. In a genetics experiment, researchers mate a calico-colored female cat (XBXO) with an orange-colored male cat (XOY) to produce an F1 generation. The researchers record observations for the cats in the F1 generation and plan to use the data to perform a chi-square goodness-of-fit test for a model of X-linked inheritance. The data for the chi-square goodness-of-fit test are presented in Table 1.
The researchers calculate a chi-square value of 4.6 and choose a significance level of p=0.05. Which of the following statements best completes the chi-square goodness-of-fit test?

A researcher observes that when two heterozygous plants with red flowers are crossed, the resulting offspring include plants with red, white, or pink flowers. The researcher proposes the null hypothesis that flower color is the result of independent assortment and incomplete dominance. The researcher calculates a chi-square value of 7.3. Assuming two degrees of freedom, which of the following is the correct interpretation of the chi-square analysis,
using a -value of 0.05?

A scientist is investigating the possibility that two traits in a particular plant are determined by genes that are on the ame chromosome. The scientist crossed a plant that is homozygous dominant for both traits with a plant that is homozygous recessive for both traits. The heterozygous offspring in the F1 generation were then crossed with a plant that is homozygous recessive for both traits. The results expected if the genes independently assort and the observed results are presented in the table.
Which of the following critical values should the scientist use for the chi-square analysis of the data?

A series of crosses is performed with fruit flies (Drosophila melanogaster) to examine inheritance of the genes vestigial (vg) and cinnabar (cn). The recessive vg allele causes small, malformed wings called vestigial wings. The recessive cn allele causes bright-red eyes called cinnabar eyes.
In the first cross, a female with wild-type wings and eyes is mated with a male with vestigial wings and cinnabar eyes. All the F1 individuals have wild-type wings and eyes. In the second cross, female F1 flies are mated with males with vestigial wings and cinnabar eyes. The phenotypes of 500 F2 individuals are shown in the table
Which of the following is the most likely explanation of the results?

• Directions: Each group of questions below concerns an experimental or laboratory situation or data. In each case, first study the description of the situation or data. Then choose the one best answer to each question following it.
A male fruit fly (Drosophila melanogaster) with red eyes and long wings was mated with a female with purple eyes and vestigial wings. All of the offspring in the F1 generation had red eyes and long wings. These F1 flies were test crossed with purple-eyed, vestigial-winged flies. Their offspring, the F2 generation, appeared as indicated below.

If in the F1 and F2 generations the same characteristics appeared in both males and females, it would be safe to
assume that these traits for eye color and wing length

In the F2 generation, the results are best explained by the fact that

A student in a biology class crossed a male Drosophila melanogaster having a gray body and long wings with a female D. melanogaster having a black body and apterous wings. The following distribution of traits was observed in the offspring.
Which of the following is supported by the data?

In sheep, eye color is controlled by a single gene with two alleles. When a homozygous brown-eyed sheep is crossed with a homozygous green-eyed sheep, blue-eyed offspring are produced. If the blue-eyed sheep are mated with each other, what percent of their offspring will most likely have brown eyes?

Eye pigment in a particular strain of fly is determined by two genes. An autosomal gene that controls the color of the pigments in the eye has two alleles: a dominant allele (R) that results in red eyes and a recessive allele (r) that results in sepia eyes. A sex-linked gene that controls the expression of the colored pigments also has two alleles: a dominant allele (T) that allows for expression of the colored pigments and a recessive allele (t) that does not allow for expression of the colored pigments. Individuals without a T allele have white eyes regardless of the alleles of other eye-color genes.
Which of the following represents a cross between a white-eyed female and a red-eyed male?

In the pedigree above, circles represent females, squares represent males, and shaded figures represent individuals expressing a specific trait. The expression of this trait is most likely due to which of the following?

The relative location of four genes on a chromosome can be mapped from the following data on crossover frequencies
Which of the following represents the relative positions of these four genes on the chromosome?

Which of the following best describes the hydrolysis of carbohydrates?

Protoporphyria is a genetic disorder characterized by an extreme sensitivity to sunlight. One form of protoporphyria is caused by a mutation in the ALAS2
gene that results in the accumulation of protoporphyrin, an organic compound, in the blood, liver, and skin. The pedigree in Figure 1 shows the incidence of protoporphyria in a particular family.

Which of the following best describes the genotype of the individual identified with an asterisk in the pedigree in
Figure 1 ?

Which of the following best describes the inheritance pattern illustrated in Figure 1 ?

Figure 1 shows the inheritance of a particular genetic condition in three generations of one family. Which of the following best explains the observed pattern of inheritance?

Gregor Mendel’s pioneering genetic experiments with pea plants occurred before the discovery of the structure and function of chromosomes. Which of the following observations about inheritance in pea plants could be explained only after the discovery that genes may be linked on a chromosome?

The fertilization of ovules from plant Q by pollen from plant R results in the production of seeds. What percent of the genes in each offspring’s chloroplasts will have been inherited from plant R?

In order to determine the effects of age on the accumulation of mitochondrial mutations, mitochondrial DNA samples from young mice (3 months) and old mice (30 months) were observed for mutations.
Which of the following is a correct analysis of this data set?

An experiment was performed to determine the mode of inheritance of two mouse genes, one for fur color and one for fur length. It is known that black fur (B ) is dominant over white fur (b ) and that long fur (L ) is dominant over short fur (l ). To determine how the genes are inherited, a cross was performed between two true-breeding mice, one with long black fur and one with short white fur. Their progeny, the F1 generation, all had long black fur. Five F1
male-female pairs were then crossed with one another. The F2 generation phenotypes for each cross are shown in Table 1.
Which of the following is the mean number per cross of F2 generation offspring that are the result of crossing over?

The pedigree below shows the inheritance of a dominant allele of a gene in a family over several generations.
Circles represent females and squares represent males. Shaded symbols indicate individuals carrying the allele.
The pedigree suggests that the gene is on a nuclear chromosome, and not on mitochondrial DNA, because

Pigeons demonstrate ZW sex determination, such that a ZZ genotype produces a male and a ZW genotype produces a female. The gene for feather color is located on the Z chromosome, and the red allele is dominant over the brown allele. Three crosses between brown male pigeons and red female pigeons were performed, and the results are shown below.
Which of the following is the mean number of male offspring produced by the three crosses?

In humans, red-green color blindness is a sex-linked recessive trait. If a man and a woman produce a color-blind son, which of the following must be true?

In fruit flies, sepia eyes and ebony body are traits that display autosomal recessive patterns of inheritance. To investigate whether the traits are genetically linked, students cross wild-type flies with a line of flies that have sepia eyes and ebony bodies. The students observe that all the flies in the F1 generation have normal eyes and normal bodies. The students allow the flies in the F1 generation to mate and produce an F2 generation. The students then record observations for the flies in the F2 generation and use the data to perform a chi-square goodness-of-fit test for a model of independent assortment. The setup for the chi-square goodness-of-fit test is presented in Table 1.
The students calculate a chi-squared value of 92.86 and compare it with a critical value of 7.82. Which of the following best completes the chi-square goodness-of-fit test?

A student carries out a genetics experiment with fruit flies to investigate the inheritance pattern of the white eye trait. The student crosses a homozygous white-eyed female with a wild-type male and records observations about the flies in the F1 generation. The student plans to use the F1 data to perform a chi-square goodness-of-fit test for a model based on an X-linked recessive pattern of inheritance. The student will use one degree of freedom and a
significance level of p=0.05. The setup for the student’s chi-square goodness-of-fit test is presented in Table 1.
The student calculates a chi-square value of 0.36. Which of the following statements best completes the student’s chi-square goodness-of-fit test?

In Drosophila melanogaster the allele for wild-type tan body color (B) is dominant to the recessive allele for black body color (b) . Similarly, the allele for wild-type wing shape (V)
is dominant to the recessive allele for vestigial wing phenotype (v). In the cross diagrammed above, the expected and observed results are shown. Which of the following best explains the observed results of the cross?

A culture of white-eyed fruit flies (Drosophila melanogaster) was maintained for many generations. Females from the stock white-eyed culture were crossed with red-eyed (wild-type) males. The F1 females were crossed with the white-eyed males from the original culture. The resulting phenotypes of the progeny are summarized below.
There are white-eyed females in the F2 generation because

The tiny blue-eyed Mary flower is often one of the first flowers seen in the spring in some regions of the United States. The flower is normally blue, but sometimes a white or pink flower variation is found.
The following data were obtained after several crosses.
Which of the following statements best explains the data?

The tiny blue-eyed Mary flower is often one of the first flowers seen in the spring in some regions of the United States. The flower is normally blue, but sometimes a white or pink flower variation is found.
The following data were obtained after several crosses.
Which of the following statements best explains the data?

A culture of white-eyed fruit flies (Drosophila melanogaster) was maintained for many generations. Females from the stock white-eyed culture were crossed with red-eyed (wild-type) males. The F1 females were crossed with the white-eyed males from the original culture. The resulting phenotypes of the progeny are summarized below.
Which of the following best describes the mode of inheritance of eye color in the white culture?

An African violet grower observes that genetically identical African violet plants growing near the walls of the greenhouse have white flowers, that plants growing farther away from the walls have pale blue flowers, and that plants growing nearest the center of the greenhouse have dark blue flowers.
Which of the following best explains the differences in flower color of the African violets in the greenhouse?

Butterflies of the genus Colias live in the Rocky Mountains, where they experience a wide range of temperatures. Different variants of a particular glycolytic enzyme in the flight muscles are optimally active at different temperatures. Within the same population, some individual butterflies fly most effectively at 29°C , while others fly most effectively at 40°C. Still others can be equally active at both temperatures. Which of the following claims is
most consistent with the observed butterfly behavior?

A scientist studying phenotypic variation in a species of butterfly observed that genetically identical caterpillars grown in similar cages but exposed to different colored lights developed into butterflies with differences in wing color and body size, as shown in Table 1.
Which of the following best explains the cause of the phenotypic variation observed in the butterflies?

Researchers investigated whether time of day affects the rate at which certain mRNAs produced by plants are broken down. At either 1 hour after the start of the light period (morning) or 8 hours after the start of the light period (afternoon), the researchers treated identical plant seedlings with a compound that blocks transcription (time=0min). The researchers measured the percent remaining of two mRNAs, mRNA G and mRNA H,
over the course of 120 minutes. The data are shown in Figure 1.
Based on the data, which of the following best describes the relationship between light and the degradation of mRNA G and mRNA H?

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both
dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained.

Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled?

A student placed 20 tobacco seeds of the same species on moist paper towels in each of two petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both
dishes. The dishes were examined after 7 days and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained.

Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled?

Hydrangea flowers differ in color based on interactions between a pigment in the flower cells and aluminum ions dissolved in water absorbed from the soil. When aluminum ions are present, the pigment is blue; when aluminum ions are absent, the pigment is pink. The amount of aluminum ions the plant can absorb is dependent on the pH of the soil.
Which of the following questions will best help a researcher design an experiment to learn about the relationship between hydrangea flower color, aluminum, and pH?

In the spring and summer, the fur of an arctic fox contains a pigment called melanin that gives the fox’s fur a dark color. In the fall and winter, the fur of the arctic fox is white.
Which of the following most likely explains how the changing seasons result in changing fur color in an arctic fox?

Australian dragon lizards have a ZW sex-determination system. The male genotype is homogametic (ZZ), and the female genotype is heterogametic (ZW). However, all eggs incubated at temperatures above 32°C tend to develop into females.
Which of the following best explains how the development of phenotypic female Australian dragon lizards with a ZZ genotype occurs when incubation temperatures are above 32°C?

Some green sea turtle females deposit their eggs in nests that are dug on warm, tropical beaches. Researchers have studied the effects of temperature on the hatching rate and the proportion of female to male hatchlings produced at different average nest temperatures in Suriname (Figure 1). At temperatures below 23°C or above 33°C, the eggs do not develop.
Which of the following best describes the results shown in Figure 1 ?

Red-green color blindness in humans is caused by a recessive allele located on the X
chromosome. Figure 1 shows the potential offspring of a female who is red-green color-blind and a male with full-color vision. All of the possible male offspring would be color-blind, and all of the possible female offspring would have full-color vision.
If during the production of male gametes an error in meiosis occurred, sperm containing both an X and a Y chromosome could be produced.
How would the extra chromosome affect the male offspring produced by the gamete?

A genetic counselor is consulted by a young man who is worried about developing Huntington’s disease, an inherited disorder caused by a dominant allele of a single gene. The young man explains that his cousin was recently diagnosed with Huntington’s disease, and the news has caused him to consider his own risk of developing the disorder. Which of the following questions will best help the genetic counselor to evaluate the risk of the young
man developing Huntington’s disease and transmitting it to his children?

Which of the following occurs in all species of living organisms and may lead to an increase in genetic variation?

The diagram above depicts a karyotype of an individual human. Which of the following statements concerning the karyotype in the diagram is true?

Figure 1 illustrates the X and Y chromosomes during meiosis I and meiosis II of normal spermatogenesis in a mammal species.
If the normal spermatogenesis is disrupted, the gametes can have different chromosomes than expected. Which of the following is the most likely cause of one of the four gametes having two X chromosomes and one having neither an X nor a Y chromosome?

Based on the pedigree in Figure 1, which of the following best explains the observed pattern of inheritance?

Trisomy 21 is a condition in which a child is born with an extra chromosome in pair 21. Researchers assessed the frequency of children born with trisomy 21 by age of the mothers at birth (maternal age) and primary cause of the error leading to trisomy 21. The findings are presented in Figure 1.
Based on the data in Figure 1, which of the following is most likely the primary cause of the pattern of frequency of trisomy 21 births in the selected maternal age-groups?

A spermatocyte produces the following four sperm cells.
These cells are the result of nondisjunction during which of the following phases?