AP BIO: Unit 5 Topic Questions

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?

D. Nondisjuction of the X chromosome during meiosis 2

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?

A. In sweet pea plants, the gene for flower color and the gene for pollen grain shape are genetically linked

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

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?

A. Is the level of genetic variation in the gametes related to the amount of DNA methylation observed?

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 the gene into the DNA of a bacterial cell?

A. The recombinant bacterium will produce human insulin using its own transcription and translation machinery.

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 (1). 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 F2 generation offspring that are the result of crossing over?

B. 2.2

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?

B. A recessive mutation on a somatic chromosome

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. DNA analysis indicates that the genes for antibiotic resistance are not normally present in bacterial chromosomal DNA. 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?

B. The genes for antibiotics resistance are located on a plasmid that can be passed to neighboring bacteria

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?

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 Based on the data in the figure, which of the following is most likely the primary cause of the pattern of frequency of trisomy 21 in the selected maternal age groups?

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 Which of the following statements correctly describes the chromosomes in each daughter cell at the end of meiosis I?

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 arrangement 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?

C. How does the independent assortment of the two sets of homologous chromosome increase genetic diversity

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?

C. The male offspring would have full-color vision, because of the presence of the extra X chromosome

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?

D. 9

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?

D. Incubation temperatures above 32°C inhibit the genes on the Z chromosome that produce proteins necessary for male development.

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

D. Mitosis produces two identical diploid daughter cells after one round of division. Meiosis produces four haploid daughter cells after two rounds of division

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?

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 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?

D. There is an increase in the mean number of mutations for the two age groups of 9.2 mutations per 106 base pairs. This is more critical in female mammals since mitochondria are maternally inherited.

A scientist studying phenotype 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 wig color and body size, as shown in Table 1. Which of the following best explains the cause of the phenotype variation observed in the butterflies?

D. There was differential gene expression of wing color and body size in response to the colors of light the caterpillars were exposed to