Unit 5 MCQ

Question 1

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

Answer 1

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.

Question 2

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?

Answer 2

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

Question 3

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?

Answer 3

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.

Question 4

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?

Answer 4

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

Question 5

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

Answer 5

Is the distance between two gene loci related to crossover rate?

Question 6

Which of the following questions about genetic diversity could most appropriately be answered by analysis of the model in Figure 1 ?

Answer 6

How does the independent assortment of the two sets of homologous chromosomes increase genetic diversity?

Question 7

How would the extra chromosome affect the male offspring produced by the gamete?

Answer 7

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

Question 8

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?

Answer 8

Nondisjunction of the X chromosome during meiosis II

Question 9

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?

Answer 9

At older maternal ages, the incidence of errors in meiosis during egg production increases, which leads to an increase in nondisjunction.

Question 10

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?

Answer 10

An enzyme responsible for flower color does not fold correctly in cooler temperatures, and the greenhouse is warmest in the center.

Question 11

Which of the following best explains the cause of the phenotypic variation observed in the butterflies?

Answer 11

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

Question 12

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?

Answer 12

The null hypothesis cannot be rejected because the chi-square value is less than the critical value.

Question 13

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?

Answer 13

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

Question 14

Which of the following best explains how the sweet pea plants in the parental generation produce F1 offspring with 14 chromosomes?

Answer 14

Meiosis I and II lead to the formation of cells with 7 chromosomes. During meiosis I , homologous chromosomes separate. During meiosis II , sister chromatids separate. Two cells combine during fertilization to produce offspring with 14 chromosomes.

Question 15

Which of the following questions would be most useful to researchers trying to determine the role of meiosis in the F2 phenotypic frequencies?

Answer 15

What is the recombination frequency between the genes for petal shape and pollen shape?

Question 16

How many degrees of freedom should be used when looking up the critical value for a chi-square analysis of the ratios of phenotypes observed among the F2 offspring versus the expected phenotypic ratio assuming independent assortment?

Answer 16

3

Question 17

For sexually reproducing diploid parent cells, which of the following statements best explains the production of haploid cells that occurs in meiosis but not in mitosis?

Answer 17

Separation of chromatids occurs once, and there are two rounds of cell division in meiosis.

Question 18

Which of the following best explains a distinction between metaphase I and metaphase II?

Answer 18

Homologous pairs of chromosomes are aligned during metaphase I , but individual chromosomes are aligned during metaphase II .

Question 19

A compound that prevents the separation of the homologous chromosomes in anaphase I is being studied. Which of the following questions can be best answered during this study?

Answer 19

Is there a pattern to the movement of homologous chromosomes in the presence of this compound?

Question 20

Based on Figure 1, which of the following questions could best be addressed?

Answer 20

Does synapsis of homologous chromosomes in the parent cell contribute to an increase in genetic diversity in the daughter cells?

Question 21

Which of the following is closest to the calculated chi-square (χ2) value for the data presented in Table 1?

Answer 21

72.01

Question 22

Based on the data in Figure 1, which of the following is the best prediction of the mode of inheritance of red eyes in Japanese koi?

Answer 22

The allele for red eyes is inherited in an autosomal dominant pattern.

Question 23

Using a significance level of p=0.05, which of the following statements best completes a chi-square goodness-of-fit test for a model of independent assortment

Answer 23

The calculated chi-square value is 3.91, and the critical value is 7.82. The null hypothesis cannot be rejected.

Question 24

For this condition, which of the following modes of inheritance is most consistent with the observations?

Answer 24

Autosomal dominant

Question 25

Which of the following tables best shows the expected values in the F2 generation for a chi-square goodness-of-fit test for a model of independent assortment?

Answer 25

Phenotype Expected
Purple, long 1199
Purple, round 400
Red, long 400
Red, round 133

Question 26

Which of the following best predicts the effect of adding this inhibitor to a culture of plant cells?

Answer 26

Plant cells will be unable to perform glycolysis due to the inhibitor and will die.

Question 27

The students plan to use a significance level of p=0.01. Which of the following is the most appropriate critical value for the students to use in their chi-square goodness-of-fit test?

Answer 27

11.34

Question 28

The mean map distance between gene R and gene L is closest to which of the following?

Answer 28

28 map units

Question 29

The researchers calculated a chi-square value of 29.25. If there are three degrees of freedom and the significance level is p=0.05, which of the following statements best completes the chi-square test?

Answer 29

The critical value is 7.82, and the null hypothesis can be rejected because the calculated chi-square value is greater than the critical value.

Question 30

Which of the follow indicates the mean number per cross of F2 plants producing medium-red grain and correctly explains the distribution of the phenotypes?

Answer 30

The mean number of medium-red phenotypes per cross is 20.8. The distribution of phenotypes suggests that multiple genes are involved in grain color determination.

Question 31

The mean number of fruit flies per student that are homozygous recessive for both genes is closest to which of the following?

Answer 31

29

Question 32

Which of the following statements best explains how the fur color can be different in Himalayan rabbits raised under different temperature conditions?

Answer 32

The environment determines how the genotype is expressed.

Question 33

Which of the following best describes an advantage of the phenotypic plasticity displayed by the tadpoles?

Answer 33

It gives the tadpoles increased versatility with respect to diet.

Question 34

Which of the following best explains how the leaves from the same plant can have different stomatal densities when exposed to an elevated carbon dioxide level?

Answer 34

Leaf growth is promoted through increased photosynthesis, but the genetically regulated rate of stomatal production is not altered, leading to a decrease in stomatal density.

Question 35

Which of the following best predicts the effect of the chromosomal segregation error shown in Figure 1?

Answer 35

Half of the resulting gametes will have the correct number of chromosomes, and the other half will have an incorrect number of chromosomes.

Question 36

If the woman and a man with normal clotting function have children, what is the probability of their children exhibiting hemophilia A?

Answer 36

50 percent for sons, 0 percent for daughters

Question 37

Which of the following is most likely the immediate cause of the first appearance of Huntington’s disease in a person?

Answer 37

An allele with more than 39 CAG repeats was inherited by the affected person.