Unit 5 AP bio

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

1/64

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

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 F1F1 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?

7.81

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

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. (C)

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

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

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?

Environmental factors cause changes in gene expression, resulting in seasonal variations in pigment production.

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? (C)

During prophase II 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? (A)

Scientists have found that DNADNA 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? (A)

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 G2G2 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. (D)

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 F1F1 generation, all had long black fur. Five F1F1 male-female pairs were then crossed with one another. The F2F2 generation phenotypes for each cross are shown in Table·1. Which of the following is the mean number per cross of F2F2 generation offspring that are the result of crossing over?

2.2

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 6464. 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?

36

Pigeons demonstrate ZWZW sex determination, such that a ZZZZ genotype produces a male and a ZWZW genotype produces a female. The gene for feather color is located on the ZZ 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 9:3:3:19:3:3:1 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.

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. (D)

The critical value for a chi-square test with a significance level of p=0.05�=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.

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 F1F1 generation have normal eyes and a normal body color. The students then allow the F1F1 flies to mate and produce an F2F2 generation. The students record observations about the flies in the F2F2 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�=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.

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 F1F1 generation are tall and have large fruits. The researchers cross the F1F1 plants with one another to generate an F2F2 generation. The researchers record observations for the F2F2 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�=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.

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�1 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 5.55.5. Based on their calculation, the researchers would most likely conclude which of the following?

The differences between observed data and expected data are due to chance.

Red-green color blindness in humans is caused by a recessive allele located on the XX 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. 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.

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

The trait is autosomal recessive, because the cross between individuals I-1I-1 and I-2I-2 produced an affected offspring.

In order to determine the effects of age on the accumulation of mitochondrial mutations, mitochondrial DNADNA 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.