unit 5 bio
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 1/64 B 1/32 C 1/16 D 1/8
A
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 ? 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
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
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? 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
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? A Environmental factors cause changes in gene expression, resulting in seasonal variations in pigment production. B Environmental factors cause different mutations in DNADNA during different seasons, resulting in seasonal changes in fur phenotype. C Environmental factors cause proteins to be translated using different genetic codes during different seasons, resulting in variations in pigment production. D Environmental factors cause enzymes to react with different substrates, resulting in the accumulation of different pigments.
A
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 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 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? A 0% B 25% C 50% D 100%
A
The researchers choose a significance level of p=0.05. Which of the following best completes the chi-square goodness-of-fit test? 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.
A
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)?
After G2 checkpoint - 78 After Meiosis - 39 After Fertilization - 78
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? 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
Based on the inheritance pattern shown in Figure 1, which of the following best predicts the nature of the original mutation? 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
Based on the pedigree in Figure 1, which of the following best explains the observed pattern of inheritance? 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
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? 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 probability that individual III-5III-5 will develop Friedreich's ataxia is closest to which of the following? A 0% B 25% C 50% D 75%
B
Which of the following best describes the inheritance pattern illustrated in Figure 1 ? 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
Which of the following is the mean number per cross of F2 generation offspring that are the result of crossing over? A 1 B 2.2 C 2.4 D 5.8
B
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? A 4 B 12 C 36 D 48
C
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 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
Based on the data, which of the following best describes the relationship between light and the degradation of mRNA GmRNA G and mRNA HmRNA H? A Exposure to light causes the degradation of both mRNA G and mRNA H. B mRNA G and mRNA H degrade at the same rate during morning exposure to light. C A longer exposure to light increases the rate of mRNA G degradation but not of mRNA H degradation. D Exposure to more-intense afternoon light causes both mRNA G and mRNA H to degrade more rapidly in the afternoon than in the morning.
C
How would the extra chromosome affect the male offspring produced by the gamete? 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
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 ? 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
The diagram above depicts a karyotype of an individual human. Which of the following statements concerning the karyotype in the diagram is true? 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 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? A The critical value is 0.05, and the student cannot reject the null hypothesis. B The critical value is 0.05, and the student can reject the null hypothesis. C The critical value is 3.84, and the student cannot reject the null hypothesis. D The critical value is 3.84, and the student can reject the null hypothesis.
C
Which of the following best explains why triploid bananas do not produce seeds? 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
Which of the following critical values should the scientist use for the chi-square analysis of the data? (4 groups) A 3.00 B 3.84 C 7.81 D 8.00
C
Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1 ? A Does crossing-over generate more genetic diversity than the fusion of gametes does? B Does DNA methylation prevent independent assortment during metaphase IIII? 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
Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis I? 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
protoporphyria - Which of the following best describes the genotype of the individual identified with an asterisk in the pedigree in Figure 1 ? A Two dominant ALAS2 alleles B Two recessive ALAS2 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
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? 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
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? 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
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? 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
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? 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 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 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 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 The null hypothesis cannot be rejected, and the students should conclude that the data fit a model of independent assortment. B The null hypothesis cannot be rejected, and the students should conclude that the data may have resulted from genetic linkage. C The null hypothesis can be rejected, and the students should conclude that the data fit a model of independent assortment. D The null hypothesis can be rejected, and the students should conclude that the data may have resulted from genetic linkage.
D
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. Which of the following statements best explains the data? 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
Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled? 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
Which of the following is a correct analysis of this data set? A There is an increase in the mean number of mutations for the two age groups of 9.0 mutations per 10^6 base pairs. This is more critical in male mammals since mitochondria are paternally inherited. B There is an increase in the mean number of mutations for the two age groups of 9.0 mutations per 10^6 base pairs. This is more critical in female mammals since mitochondria are maternally inherited. C There is an increase in the mean number of mutations for the two age groups of 9.2 mutations per 10^6 base pairs. This is more critical in male mammals since mitochondria are paternally inherited. D There is an increase in the mean number of mutations for the two age groups of 9.2 mutations per 10^6 base pairs. This is more critical in female mammals since mitochondria are maternally inherited.
D
Which of the following is the mean number of male offspring produced by the three crosses? A 27 B 20 C 11 D 9
D