bio test unit 5
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? Responses a) 0% b) 25% c) 50% d) 100%
a) 0%
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? Responses a) 1/64 b) 1/32 c) 1/16 d) 1/8
a) 1/64
During prophase I replicated homologous chromosomes pair up and undergo synapsis. What testable question is generated regarding synapsis and genetic variability by Figure 1 ? Responses a) Is the distance between two gene loci related to crossover rate? b) Does crossing over occur more often in some chromosomes than in others? c) Is crossing over inhibited by methylation? d) Is crossing over promoted by methylation?
a) Is the distance between two gene loci related to crossover rate?
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? Responses a) Is the level of genetic variation in the gametes related to the amount of DNA methylation observed? b) Without crossing-over, will gametes be viable and be able to produce zygotes? c) Does DNA methylation result in shorter chromosomes? d) Is this species of fungus a diploid organism?
a) Is the level of genetic variation in the gametes related to the amount of DNA methylation observed?
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 F1generation 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 F2data 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. Table 1. A chi-square goodness-of-fit test for incomplete dominance PhenotypeObservedExpectedRed flowers6456Pink flowers107112White flowers5356 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? Responses a) The calculated chi-square value is 1.53, and the null hypothesis cannot be rejected. b) The calculated chi-square value is 1.53, and the null hypothesis can be rejected. c) The calculated chi-square value is 98, and the null hypothesis cannot be rejected. d) The calculated chi-square value is 98, and the null hypothesis can be rejected.
a) The calculated chi-square value is 1.53, and the null hypothesis cannot be rejected.
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? Responses a) The eye-color gene is likely autosomal because males and females have similar phenotype ratios. b) The eye-color gene is likely autosomal because more females have sepia eyes than males do. c) The eye-color gene is likely sex-linked because the males and females have similar phenotype ratios. d) The eye-color gene is likely sex-linked because the males and females display both phenotypes.
a) The eye-color gene is likely autosomal because males and females have similar phenotype ratios.
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 p-value of 0.05 ? Responses a) The null hypothesis should be rejected because the critical value is less than the calculated value. b) The null hypothesis should not be rejected because the critical value is less than the calculated value. c) The null hypothesis should not be rejected because the critical value is greater than the calculated value. d) The null hypothesis should be rejected because the critical value is greater than the calculated value.
a) The null hypothesis should be rejected because the critical value is less than the calculated value.
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. Figure 1. A pedigree of a family affected by Friedreich's ataxia 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. Figure 2. FXN gene fragment sizes for several family members. A sample of DNA with fragments of known lengths was used for comparison. 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). Figure 3. The modeled DNA triple-helix structure that can form in areas with multiple GAA triplets Based on the data in Figure 1, which of the following best describes the inheritance pattern of Friedreich's ataxia? a) Autosomal recessive b) Autosomal dominant c) Sex-linked recessive d) Sex-linked dominant
a) autosomal recessive
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. Question Which of the following pedigrees most accurately represents a family with a history of Tay-Sachs disease? a) 7 things highlighted b) 2 things highlighted c) 10 things highlighted d) 6 things highlighted
b) 2 things highlighted
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. Table 1. Number of F2 generation phenotypes for five crosses Phenotype Cross 1 Cross 2 Cross 3 Cross 4 Cross 5 Long black fur 6 5 5 6 7 Long white fur 1 1 0 2 2 Short black fur 0 2 1 1 1 Short white fur 2 3 3 2 2 Which of the following is the mean number per cross of F2 generation offspring that are the result of crossing over? Responses a) 1 b) 2.2 c) 2.4 d) 5.8
b) 2.2
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. Figure 1. A pedigree of a family affected by Friedreich's ataxia 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. Figure 2. FXN gene fragment sizes for several family members. A sample of DNA with fragments of known lengths was used for comparison. 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). Figure 3. The modeled DNA triple-helix structure that can form in areas with multiple GAA triplets Question The probability that individual III-5 will develop Friedreich's ataxia is closest to which of the following? Responses a) 0% b) 25% c) 50% d) 75%
b) 25%
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. Figure 1. Pedigree of Russian blue cats owned by Russian Blue Club Based on the inheritance pattern shown in Figure 1, which of the following best predicts the nature of the original mutation? Responses a) A recessive mutation on the X chromosome b) A recessive mutation on a somatic chromosome c) A dominant mutation on the X chromosome d) A dominant mutation on a somatic chromosome
b) A recessive mutation on a somatic chromosome
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)? Responses a) After G 2 Checkpoint After Meiosis After Fertilization 156 78 39 b) After G 2 Checkpoint After Meiosis After Fertilization 78 39 78 c) After G 2 Checkpoint After Meiosis After Fertilization 156 39 78 d) After G2CheckpointAfterMeiosisAfterFertilization787839
b) After G 2 Checkpoint After Meiosis After Fertilization 78 39 78
Which of the following best supports the claim that organisms of different domains share a common ancestor? Responses a) Photosynthesis occurs in chloroplasts, and the citric acid cycle occurs in mitochondria. b) Glycolysis occurs in both prokaryotic cells and eukaryotic cells. c) Introns are present in eukaryotic DNA but not in prokaryotic DNA. d) Errors in DNA synthesis provide some of the genetic variation in a population.
b) Glycolysis occurs in both prokaryotic cells and eukaryotic cells.
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? Responses a) Blue flowers are incompletely dominant to pink flowers. b) Pink flower color is a trait recessive to blue flower color. c) Pink flower color is the result of somatic mutations in the flower color gene. d) A previous generation of the blue-flowered parent must have included 50 percent pinkflowered plants.
b) Pink flower color is a trait recessive to blue flower color.
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. Question Which of the following best describes the inheritance pattern illustrated in Figure 1 ? Responses a) Protoporphyria has an autosomal recessive inheritance pattern. b) Protoporphyria has an X -linked dominant inheritance pattern. c) Protoporphyria has an X-linked recessive inheritance pattern. d) Protoporphyria has a mitochondrial inheritance pattern.
b) Protoporphyria has an X -linked dominant inheritance pattern
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 be 5.5. Based on their calculation, the researchers would most likely conclude which of the following? Responses a) The genes that determine these two traits are likely on the same chromosome. b) The differences between observed data and expected data are due to chance. c) The genes mutated since the researchers began the experiment and now have a different inheritance pattern. d) The allele frequencies of the offspring have changed, suggesting the population is evolving.
b) The differences between observed data and expected data are due to chance.
Based on the pedigree in Figure 1, which of the following best explains the observed pattern of inheritance? Responses a) The trait is autosomal dominant, because the cross between individuals I-3 and I-4 produced an affected offspring. b) The trait is autosomal recessive, because the cross between individuals I-1 and I-2 produced an affected offspring. c) The trait is sex-linked dominant, because the cross between individuals II-5 and II-6 produced an affected male. d) The trait is sex-linked recessive, because the cross between individuals II-2 and II-3 produced an affected female.
b) The trait is autosomal recessive, because the cross between individuals I-1 and I-2 produced an affected offspring.
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? Responses a) Were you and your cousin born in the same geographical area? b) Were your parents or grandparents ever diagnosed with Huntington's disease? c) Were you in physical contact with a person diagnosed with Huntington's disease? d) Were you ever exposed to substances that are suspected of being mutagens?
b) Were your parents or grandparents ever diagnosed with Huntington's disease?
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? Responses a) −0.26 b) 0.20 c) 0.95 d) 1.25
c) 0.95
A 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 produced was 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? Responses a) 4 b) 12 c) 36 d) 48
c) 36
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? a) 4 chromosomes going towards the poles b) separated chromosomes c) 4 chromosomes in the center of cell d) 2 chromosomes
c) 4 chromosomes in the center of cell
A scientist is investigating the possibility that two traits in a particular plant are determined by genes that are on the same 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. PhenotypeExpected Number in F2Observed Number in F2Long stems, white flowers2517Short stems, red flowers2519Long stems, red flowers2531Short stems, white flowers2533Total number of plants100100 Which of the following critical values should the scientist use for the chi-square analysis of the data? Responses a) 3.00 b) 3.84 c) 7.81 d) 8.00
c) 7.81
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? a) Warmer temperatures result in genotypic alterations, which result in flower color differences. b) The plants along the walls of the greenhouse are homozygous recessive and therefore have white flowers. c) An enzyme responsible for flower color does not fold correctly in cooler temperatures, and the greenhouse is warmest in the center. d) More light is available along the walls of the greenhouse, so the flowers need less pigment to absorb sunlight for photosynthesis.
c) An enzyme responsible for flower color does not fold correctly in cooler temperatures, and the greenhouse is warmest in the center.
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. Figure 1. Incidence and primary cause of trisomy 21 by maternal age-group 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? Responses a) At older maternal ages, there is an increase in the number of errors during mitosis, which leads to an increase in nondisjunction during egg production. b) The incidence of nondisjunction errors in meiosis during sperm production is positively correlated with increasing maternal age. c) At older maternal ages, the incidence of errors in meiosis during egg production increases, which leads to an increase in nondisjunction. d) Errors in meiosis leading to nondisjunction are more likely to occur during meiosis I than during meiosis II.
c) At older maternal ages, the incidence of errors in meiosis during egg production increases, which leads to an increase in nondisjunction.
Table 1 shows the stage and number of cells and chromosomes per cell at the end of the stage in a 2n=24 organism. Table 1. Cell and chromosome count during selected phases of meiosis Stage Number of Cells Number of Chromosomes per Cell Prophase I1 24 Metaphase I1 24 Anaphase I1 24 Telophase I1 24 Beginning of Prophase II2 12 Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis I? Responses a) Each daughter cell contains 12 chromatids. Each chromatid is one of two from a single chromosome with the other one of the pair found in the other daughter cell. b) Each daughter cell contains 12 chromosomes, each composed of two chromatids. Since the chromosomes were randomly divided, one daughter cell may contain both of a pair of homologous chromosomes, while the other cell contains both of another pair of homologous chromosomes. c) Each daughter cell contains 12 chromosomes, each composed of two chromatids. Each chromosome is one of a pair of homologous chromosomes from the parent cell, with the other homologue found in the other daughter cell. d) Each daughter cell contains 24 separate chromatids. Since every two chromatids were originally joined, forming one homologous chromosome, the number of chromatids is divided by two to determine the number of chromosomes.
c) Each daughter cell contains 12 chromosomes, each composed of two chromatids. Each chromosome is one of a pair of homologous chromosomes from the parent cell, with the other homologue found in the other daughter cell.
A model showing two possible arrangements of chromosomes during meiosis is shown in Figure 1. Figure 1. Two possible arrangements of chromosomes during meiosis Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1 ? Responses a) Does crossing-over generate more genetic diversity than the fusion of gametes does? b) Does D N A methylation prevent independent assortment during metaphase 2 ? c) How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity? d) Do daughter cells that are not genetically identical to parent cells produce viable zygotes?
c) How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?
Which of the following best describes the genotype of the individual identified with an asterisk in the pedigree in Figure 1 ? Responses a) Two dominant ALAS2 alleles b) Two recessive A L A S 2 alleles c) One dominant ALAS2 allele and one recessive ALAS2 allele d) One recessive ALAS2 allele and no second allele for the ALAS2 gene
c) One dominant ALAS2 allele and one recessive ALAS2 allele
Which of the following best describes the cellular process illustrated in Figure 1 ? a) Sister chromatids separating during anaphase of mitosis b) Chromosomes lining up along the midline of the cell during mitosis c) Reducing the chromosome number during anaphase I of meiosis d) Chromatids failing to separate during meiosis
c) Reducing the chromosome number during anaphase I of meiosis
The diagram above depicts a karyotype of an individual human. Which of the following statements concerning the karyotype in the diagram is true? Responses a) The diagram illustrates a genetic condition found in females. b) The diagram indicates a mechanism for increasing genetic diversity in subsequent generations. c) The diagram illustrates the results of nondisjunction during gamete formation. d) The diagram indicates Down syndrome, a genetic condition.
c) The diagram illustrates the results of nondisjunction during gamete formation.
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. Potential Offspring With No Error in MeiosisPotential Offspring With Error in MeiosisXBYXBYXbXBXbXbYXB=Full color visionXb=Red-green colorblindXbXbXbXBYXbXBXbXbYXbXbXbXBY Figure 1. Possible offspring of a female who is red-green color-blind and a male who has full-color vision. How would the extra chromosome affect the male offspring produced by the gamete? Responses a) None of the potential offspring would be male, because the potentially male zygote would have two X chromosomes, and the Y chromosome would be ignored. b) The male offspring would all be red-green color-blind, because of interference from alleles on the Y chromosome. c) The male offspring would have full-color vision, because of the presence of the extra X chromosome. d) There would be no change to the phenotypes of the possible offspring, because the extra X chromosome would not be active.
c) The male offspring would have full-color vision, because of the presence of the extra X chromosome.
Which of the following best explains why triploid bananas do not produce seeds? Responses a) The cells of the banana plant are unable to replicate DNA, thus preventing cell division and limiting growth. b) The banana plants lack enough genetic diversity to properly hybridize. c) The production of gametes is disrupted because of unequal pairing of homologous chromosomes during meiosis. d) The production of seeds is not required because triploid plants produce gametes without fertilization.
c) The production of gametes is disrupted because of unequal pairing of homologous chromosomes during meiosis.
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 ? Responses a) The percentage of hatchlings that survive to adulthood is directly proportional to average nest temperature. b) Female sea turtles search for cooler beaches in order to have more male offspring. c) Warmer nests produce more female sea turtles than do cooler nests. d) The sex ratio of sea turtles is genetically determined.
c) Warmer nests produce more female sea turtles than do cooler nests.
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 DMD do not produce functional dystrophin and, as a result, the protein fibers, and then entire muscle cells, become damaged. The history of DMD for three generations of a family is shown in Figure 1. Figure 1. Pedigree showing instances of DMD in a family 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 the mutated 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. Figure 2. Gel electrophoresis showing the dystrophin alleles present in five members of the family Question Based on the information provided, which of the following describes the most likely pattern of inheritance for the disorder? Responses a) Autosomal recessive b) Autosomal dominant c) X-linked recessive d) Mitochondrial
c) X-linked recessive
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? Responses a) The appearance of blue in the F1 generation of the pink and white cross demonstrates that flower color is not an inherited trait but is determined by the environment. b) Flower color depends on stages of flower development, and young flowers are white, advancing to pink and then blue. c) Since the F1 and F2 phenotypes of the pink and white cross do not fit the expected genotypic and phenotypic ratios, blue-eyed Mary must reproduce by vegetative propagation. d) Flower color is an inherited trait, and the F1 and F2 phenotypes of the flowers arising from the pink and white cross can best be explained by another gene product that influences the phenotypic expression.
d) Flower color is an inherited trait, and the F1 and F2 phenotypes of the flowers arising from the pink and white cross can best be explained by another gene product that influences the phenotypic expression.
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? Responses a) Lizard embryos with a ZZ genotype cannot develop at temperatures above 32°C. b) At incubation temperatures above 32 degrees Celsius , Z chromosomes are mutated into W chromosomes. c) At incubation temperatures above 32°C, crossing over transfers genes from the W chromosome to the Z chromosome, producing females. d) Incubation temperatures above 32°C inhibit the genes on the Z chromosome that produce proteins necessary for male development.
d) Incubation temperatures above 32°C inhibit the genes on the Z chromosome that produce proteins necessary for male development.
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? Responses a) Nondisjunction of the chromosomes during meiosis I b) Nondisjunction of both the X and Y chromosomes during meiosis II c) Nondisjunction of the Y chromosome during meiosis II d) Nondisjunction of the X chromosome during meiosis II
d) Nondisjunction of the X chromosome during meiosis II
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. Table 1. Observed and expected counts of tomato plants in the F2 generation PhenotypeObservedExpectedTall plant with large fruits10490Tall plant with small fruits1730Short plant with large fruits2630Short plant with small fruits1310 The researchers choose a significance level of p=0.05. Which of the following best completes the chi-square goodness-of-fit test? Responses a) The calculated chi-square value is 9.24, and the critical value is 7.82. The null hypothesis of independent assortment can be rejected. b) The calculated chi-square value is 9.24, and the critical value is 9.49. The null hypothesis of independent assortment cannot be rejected. c) The calculated chi-square value is 13.13, and the critical value is 7.82. The null hypothesis of independent assortment can be rejected. d) The calculated chi-square value is 13.13, and the critical value is 9.49. The null hypothesis of independent assortment cannot be rejected.
d) The calculated chi-square value is 13.13, and the critical value is 9.49. The null hypothesis of independent assortment cannot be rejected.
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? Responses a) The chi-square calculated value is greater than the chi-square critical value; therefore the null hypothesis should be rejected. b) The chi-square calculated value is greater than the chi-square critical value; therefore the null hypothesis should not be rejected. c) The chi-square calculated value is less than the chi-square critical value; therefore the null hypothesis should be rejected. d) The chi-square calculated value is less than the chi-square critical value; therefore the null hypothesis should not be rejected.
d) The chi-square calculated value is less than the chi-square critical value; therefore the null hypothesis should not be rejected.
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? Responses a) The condition is passed randomly because of the independent assortment of chromosomes. b) The condition is passed from fathers to sons via a Y -linked gene. c) The condition is passed from mothers to sons via an X-linked gene. d) The condition is passed from mothers to offspring via a mitochondrial gene.
d) The condition is passed from mothers to offspring via a mitochondrial gene.
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. Question Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled? Responses a) The number of yellow-leaved seedlings in dish A on day 7 b) The number of germinated seeds in dish A on days 7 and 14 c) The death of all the yellow-leaved seedlings d) The existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
d) The existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
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? Responses a) The first division will result in crossing over between homologous chromosomes, and the second division will reduce the original number of chromosomes by half in the daughter cells. b) The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will result in each daughter cell having one-fourth of the original number of chromosomes. c) The first division will move single chromatids to each daughter cell, and the second division will double the number of chromosomes in each daughter cell. d) The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will move single chromatids to each daughter cell.
d) The first division will reduce the number of chromosomes by half for each daughter cell, and the second division will move single chromatids to each daughter cell.
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? Responses a) The allele pairs of each parent stay together, resulting in gametes that are identical to the parents. b) Gene segments on sister chromatids cross over. c) Alleles that are on nonhomologous chromosomes recombine. d) The genes for seed color and seed shape assort independently.
d) The genes for seed color and seed shape assort independently.
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. Table 1. Data for the chi-square goodness-of-fit test Phenotype Genotype Observed Expected Calico-colored female XBXO15 10 Orange-colored female XOXO6 10 Black-colored male XBY11 10 Orange-colored male XOY8 10 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? Responses a) The null hypothesis can be rejected because the chi-square value is greater than the critical value. b) The null hypothesis can be rejected because the chi-square value is less than the critical value. c) The null hypothesis cannot be rejected because the chi-square value is greater than the critical value. d) The null hypothesis cannot be rejected because the chi-square value is less than the critical value.
d) The null hypothesis cannot be rejected because the chi-square value is less than the critical value.
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. Table 1. Effect of Exposing Identical Caterpillars to Specific Colors of Light Phenotype of Adult ButterflyCaterpillars Exposed to Red LightCaterpillars Exposed to Blue LightWing colorDarkerLighterBody sizeSmallerLarger Which of the following best explains the cause of the phenotypic variation observed in the butterflies? Responses a) Different mutations occurred in the caterpillars that were exposed to different colors of light. b) The energy used to grow a larger body results in butterflies with lighter colored wings. c) Individual caterpillars evolved adaptations to survive in each of the light conditions they were exposed to. d) There was differential gene expression of wing color and body size in response to the colors of light the caterpillars were exposed to.
d) There was differential gene expression of wing color and body size in response to the colors of light the caterpillars were exposed to.
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? Responses a) How do aluminum-pigment interactions change the structure of the pigment and flower color? b) Can the pigment be used as an indicator of p H , because flower color depends on p H and aluminum? c) Does an increase in hydrogen ion concentration affect the ability of the pigment to dissolve in water? d) What will be the flower color of hydrangeas grown in soils of varying pH with or without aluminum?
d) What will be the flower color of hydrangeas grown in soils of varying pH with or without aluminum?
