Unit 5 APBIO
Based on the inheritance pattern shown in Figure 1, which of the following best predicts the nature of the original mutation?
A recessive mutation on a somatic chromosome
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?
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 Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis I?
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
Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1 ?
How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?
During prophase I replicated homologous chromosomes pair up and undergo synapsis. What testable question is generated regarding synapsis and genetic variability by Figure 1 ?
Is the distance between two gene loci related to crossover rate?
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?
Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division
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?
The calculated chi-square value is 1.53, and the null hypothesis cannot be rejected.
How would the extra chromosome affect the male offspring produced by the gamete?
The male offspring would have full-color vision, because of the presence of the extra XX chromosome.
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?
There is an increase in the mean number of mutations for the two age groups of 9.2 mutations per 106106 base pairs. This is more critical in female mammals since mitochondria are maternally inherited.
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?
2.2
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?
An enzyme responsible for flower color does not fold correctly in cooler temperatures, and the greenhouse is warmest in the center.
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?
Is the level of genetic variation in the gametes related to the amount of DNADNA methylation observed?
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?
The calculated chi-square value is 10.48, and the critical value is 11.35.
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?
The critical value is 3.84, and the student cannot reject the null hypothesis.
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?
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.
Antibiotics can be used to kill the specific pathogenic bacterium, Mycobacterium tuberculosis, that causes tuberculosis. The appearance of antibiotic-resistant strains has made it more difficult to cure M. tuberculosis infections. These antibiotic-resistant bacteria survive and pass on the genes to their offspring, making the resistant phenotype more common in the population. Which of the following statements best explains how the genes for antibiotic resistance can be transmitted between bacteria without the exchange of bacterial chromosomal DNA?
The genes for antibiotic resistance are located on a plasmid that can be passed to neighboring bacteria.
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?
The null hypothesis can be rejected, and the students should conclude that the data may have resulted from genetic linkage.
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?
The null hypothesis cannot be rejected because the chi-square value is less than the critical value.
Which of the following best predicts the effect of inserting this gene into the DNA of a bacterial cell?
The recombinant bacterium will produce human insulin using its own transcription and translation machinery.
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?
Nondisjunction of the XX chromosome during meiosis II
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?
9
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?
In sweet pea plants, the gene for flower color and the gene for pollen grain shape are genetically linked
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?
Incubation temperatures above 32°C32°C inhibit the genes on the ZZ chromosome that produce proteins necessary for male development
The researchers choose a significance level of p=0.05. Which of the following best completes the chi-square goodness-of-fit test?
The calculated chi-square value is 9.24, and the critical value is 7.82. The null hypothesis of independent assortment can be rejected.
Which of the following best explains the cause of the phenotypic variation observed in the butterflies?
There was differential gene expression of wing color and body size in response to the colors of light the caterpillars were exposed to.