Mastering Biology Chapter 15
A white-eyed female Drosophila is crossed with a red-eyed male Drosophila. Which
statement below correctly describes the results? - answer None of the females will have
white eyes.
All of the females will have red eyes because they will inherit the dominant red-eye
allele from their male parent.
In humans, what determines the sex of offspring and why? - answer The male gamete
determines sex because each male gamete can contribute either an X or a Y
chromosome.
In humans, the male produces both X- and Y-bearing sperm, whereas females only
produce X-bearing eggs.
Which of the following is true of an X-linked gene, but not of a Y-linked gene? - answer
The gene is present in both males and females.
All cells have at least one functional X chromosome.
Males are more often affected by sex-linked traits than females because - answer Males
are hemizygous for the X chromosome.
SRY is best described in which of the following ways? - answerA gene region present
on the Y chromosome that triggers male development
Red-green color blindness is a sex-linked recessive trait in humans. Two people with
normal color vision have a color-blind son. What are the genotypes of the parents? –
answer XNXn and XNY
Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having
cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will
have cinnabar eyes? - answer100%
Which of the following statements is true of linkage? - answer The closer two genes are
on a chromosome, the lower the probability that a crossover will occur between them.
What is a nondisjunction? - answer An error in cell division that causes homologous
chromosomes or sister chromatids to move to the same side of the dividing cell
, Nondisjunction refers to the failure of pairs of chromosomes or sister chromatids to
separate during meiosis or mitosis.
When can nondisjunction occur? - answerIn mitosis, when sister chromatids fail to
separate
In meiosis, when sister chromatids fail to separate
In meiosis, when homologous chromosomes fail to separate
Nondisjunction errors can occur in meiosis I, when homologous chromosomes fail to
separate, or in either mitosis or meiosis II, when sister chromatids fail to separate.
Which syndrome is characterized by the XO chromosome abnormality? - answer Turner
syndrome
Turner syndrome is characterized by a chromosome pattern of XO, or one X
chromosome and no Y chromosome.
What kind of cell results when a diploid and a haploid gamete fuse during fertilization? -
answer A triploid cell
A triploid cell has three sets of chromosomes: the two from the diploid gamete and the
one from the haploid gamete.
Of the following chromosomal abnormalities, which type is most likely to be viable in
humans? - answer Trisomy
Some trisomy’s are viable in humans, but they result in developmental abnormalities,
such as Down syndrome (trisomy 21). Only humans with trisomy’s of the small
chromosomes (13, 18, or 21) or the sex chromosomes survive past birth.
If a diploid cell undergoes meiosis and produces two gametes that are normal, and one
with n − 1 chromosomes, and one with n + 1 chromosomes, what type of error
occurred? - answer A nondisjunction error occurred in meiosis II, in which both sister
chromatids of a chromosome migrated to the same pole of the cell.
When this error occurs in meiosis II, only half of the gametes are affected.
If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes
and two gametes with n− 1 chromosomes, what type of error occurred? - answer A
nondisjunction error occurred in meiosis I, in which both members of a homologous pair
migrated to the same pole of the cell.
When this type of error occurs, half of the gametes receive one too many
chromosomes, and the other half receive one too few. When all of the gametes are
affected, the error probably occurred in meiosis I.
A white-eyed female Drosophila is crossed with a red-eyed male Drosophila. Which
statement below correctly describes the results? - answer None of the females will have
white eyes.
All of the females will have red eyes because they will inherit the dominant red-eye
allele from their male parent.
In humans, what determines the sex of offspring and why? - answer The male gamete
determines sex because each male gamete can contribute either an X or a Y
chromosome.
In humans, the male produces both X- and Y-bearing sperm, whereas females only
produce X-bearing eggs.
Which of the following is true of an X-linked gene, but not of a Y-linked gene? - answer
The gene is present in both males and females.
All cells have at least one functional X chromosome.
Males are more often affected by sex-linked traits than females because - answer Males
are hemizygous for the X chromosome.
SRY is best described in which of the following ways? - answerA gene region present
on the Y chromosome that triggers male development
Red-green color blindness is a sex-linked recessive trait in humans. Two people with
normal color vision have a color-blind son. What are the genotypes of the parents? –
answer XNXn and XNY
Cinnabar eyes is a sex-linked recessive characteristic in fruit flies. If a female having
cinnabar eyes is crossed with a wild-type male, what percentage of the F1 males will
have cinnabar eyes? - answer100%
Which of the following statements is true of linkage? - answer The closer two genes are
on a chromosome, the lower the probability that a crossover will occur between them.
What is a nondisjunction? - answer An error in cell division that causes homologous
chromosomes or sister chromatids to move to the same side of the dividing cell
, Nondisjunction refers to the failure of pairs of chromosomes or sister chromatids to
separate during meiosis or mitosis.
When can nondisjunction occur? - answerIn mitosis, when sister chromatids fail to
separate
In meiosis, when sister chromatids fail to separate
In meiosis, when homologous chromosomes fail to separate
Nondisjunction errors can occur in meiosis I, when homologous chromosomes fail to
separate, or in either mitosis or meiosis II, when sister chromatids fail to separate.
Which syndrome is characterized by the XO chromosome abnormality? - answer Turner
syndrome
Turner syndrome is characterized by a chromosome pattern of XO, or one X
chromosome and no Y chromosome.
What kind of cell results when a diploid and a haploid gamete fuse during fertilization? -
answer A triploid cell
A triploid cell has three sets of chromosomes: the two from the diploid gamete and the
one from the haploid gamete.
Of the following chromosomal abnormalities, which type is most likely to be viable in
humans? - answer Trisomy
Some trisomy’s are viable in humans, but they result in developmental abnormalities,
such as Down syndrome (trisomy 21). Only humans with trisomy’s of the small
chromosomes (13, 18, or 21) or the sex chromosomes survive past birth.
If a diploid cell undergoes meiosis and produces two gametes that are normal, and one
with n − 1 chromosomes, and one with n + 1 chromosomes, what type of error
occurred? - answer A nondisjunction error occurred in meiosis II, in which both sister
chromatids of a chromosome migrated to the same pole of the cell.
When this error occurs in meiosis II, only half of the gametes are affected.
If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes
and two gametes with n− 1 chromosomes, what type of error occurred? - answer A
nondisjunction error occurred in meiosis I, in which both members of a homologous pair
migrated to the same pole of the cell.
When this type of error occurs, half of the gametes receive one too many
chromosomes, and the other half receive one too few. When all of the gametes are
affected, the error probably occurred in meiosis I.
