bio test unit 5

Probability that the genotype ccdd will be produced by the parents CcDd x CcDd

1/16

A couple has 5 children, all sons. If the woman gives birth to a sixth child, what is the probability that the sixth child will be a son?

1/2

Probability that the genotype Aa will be produced by the parents Aa x Aa

1/2

If 2n = 48 for a particular cell, then the chromosome number in each cell after meiosis would be

24

In sheep, eye color is controlled by a single gene with two alleles. When a homozygous brown-eyed sheep is crossed with a homozygous green-eyed sheep, blue-eyed offspring are produced. If the blue- eyed sheep are mated with each other, what percent of their offspring will most likely have brown eyes?

25%

The probability that individual III-5 will develop Friedreich's ataxia is closest to which of the following?

25%

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 F1 generation were then crossed with a plant that is homozygous recessive for both traits. The results are 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

In most vertebrates, the sperm cell normally contributes which of the following to the new organism?

A haploid complement of chromosomes

If a red-eyed Drosophila female, heterozygous for white eyes, is mated to a red-eyed male, what will be the phenotypic ratios for sex and eye color in their offspring?

All the females have red eyes; half the males have red eyes and half the males have white eyes

In the pedigree to the right, squares represent males and circles represent females. Individuals who express a particular trait are represented by shaded figures. Which of the following patterns of inheritance best explains the transmission of the trait?

Autosomal dominant

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. Correct Answers Your Answers PREVNEXT

Autosomal recessive

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.

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. The following data were obtained after several crosses. Which of the following statements best explains the data?

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.

All of the following are true statements about meiosis in mammals EXCEPT:

It produces four genetically identical gametes.

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 blue-flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. These seeds germinate and grow into flowering plants. Of these plants, 36 produce blue flowers and 14 produce pink flowers. What is the best explanation for the pink-flowered offspring?

Pink flower color is a trait recessive to blue flower color.

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 ata 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 the table to the right. 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.

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?

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

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?

The eye-color gene is likely autosomal because males and females have similar phenotype ratios.

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. Correct Answers Your Answers PREVNEXT

In humans, red-green color blindness is a sex-linked recessive trait. If a man and a woman produce a color-blind son, which of the following must be true? Father is colorblind.

The mother carries the allele for color blindness.

A gene that influences coat color in domestic cats is located on the X chromosome. A female cat that is heterozygous for the gene (XBXO) has a calico-colored coat. In a genetics experiment, researchers mate a calico-colored female cat (XBXO) with an orange-colored male cat (XOY) to produce an F1 generation. The researchers record observations for the cats in the F1 generation and plan to use the data to perform a chi-square goodness-of-fit test for a model of X-inheritance. The data for the chi-square goodness-of-fit test are presented in the table. The researchers calculate a chi-square value of 4.6 and choose a significance level of p=.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.

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 ?

The null hypothesis should be rejected because the critical value is greater than the calculated value.

Which of the following best describes the cells that result from the process of meiosis in mammals?

They are genetically different from the parent cell.

In peas the trait for tall plants is dominant (T) and the trait for short plants is recessive (t). The trait for yellow seed color is dominant (Y) and the trait for green seed color is recessive (y). A cross between two plants results in 296 tall yellow plants and 104 tall green plants. Which of the following are most likely to be the genotypes of the parents?

TtYy x TTYy

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?

Were your parents or grandparents ever diagnosed with Huntington's disease?

The diagram to the right represents which of the following processes?

crossing-over

The human X and Y chromosomes...

include genes that determine an individual's sex.

Assume that genes A and B are not linked. If the probability of allele A in a gamete is 1/2 and the probability of allele B in a gamete is 1/2, then the probability that both A and B are in the same gamete is...

½ x ½