Sex-Linked Genes Practice Problems

Morgan chose to investigate the color of the eyes in the monohybrid cross he conducted with Drosophila. He crossed a red-eyed female with a white-eyed male during the parent generation. It was unknown at the time whether the gene for eye color was on sex chromosomes or autosomes. Morgan concluded that the gene for eye color in Drosophila was on the X chromosome based on which of the following observations?

In the fruit fly, Drosophila, the gene "S" for sepia body color is dominant to its allele "s" for white body color. At another gene locus on the same chromosome, the gene "V" for normal wings is dominant to its allele "v" for vestigial wings. If the two flies that have the same genotype: the alleles "S" and "V" are on one chromosome and the alleles "s" and "v" are on the homologous chromosome are crossed, which of the following is the expected phenotypic ratio of the offspring, assuming that these two gene loci do not cross over?

In the fruit fly Drosophila, the genotype w+ for the red-eye allele is dominant to its allele w, the white-eye allele. If a female Drosophila of unknown genotype was crossed with a white-eyed male fly (XwY), 50% of the male and the female offspring were red-eyed, and 50% of the male and the female offspring were white-eyed. Which of the following is the genotype of the unknown female fly?

An X-linked recessive allele is the cause of a common form of human red-green color blindness. Which of the following statements about inheritance probabilities is incorrect?

Which of the following probabilities is true if a color-blind woman marries an unaffected father?

Eye color in the common fruit fly was the first sex-linked trait to be identified by Thomas Hunt Morgan. Which of the following statements about the eye color in fruit flies is incorrect?

The X and Y chromosomes, which make up the sex chromosomes, are the ones from which sex-linked traits are inherited. The inheritance of eye color in fruit flies is sex-linked. Which of the following contains the eye color gene?

Assume that the red allele is dominant over the violet allele in Drosophila. If the gene is sex-linked, a cross of a wild-type red-eyed female with a violet-eyed male will produce? 

In fruit flies, the red eye is dominant over the white eye. When a white eye female (XrXr) is crossed to a white eye male (XrY), what would be the genotype of all females and males in the F1 generation?

In fruit flies, white eye color is a recessive X-linked trait while red eye color is dominant. What would be the eye color of the male offspring from a cross between a white-eyed female and a red-eyed male?

Which of the following could be the genotypes of a couple who have a color-blind child, but are not themselves color-blind?

Which of the following is a characteristic of the bar body in Drosophila?

X-linked dominant traits are traits that are caused by mutations on the X chromosome and exhibit a dominant inheritance pattern. Which of the following is an example of an X-linked dominant trait?

This is a rare genetic disorder that affects the breakdown of long-chain fatty acids and can lead to neurological problems and adrenal gland dysfunction.

X-linked adrenoleukodystrophy is a rare genetic disorder that affects the breakdown of long-chain fatty acids and can lead to neurological problems and adrenal gland dysfunction. What is the probability of having a son with adrenoleukodystrophy from a carrier mother and an unaffected father?

Which of the following is an example of an organism with a female heterogametic sex determination system?

In sex-influenced traits, the expression of the trait is influenced by:

The gene that controls the color of the body in Drosophila is located on the X chromosome. The wild-type recessive allele produces a yellowish-brown body color, while the mutant ebony allele produces a gray body color. A male Drosophila with a gray body mates with a female Drosophila with a yellowish-brown body. What proportion of their female offspring would be expected to have a yellowish-brown body color?

Which of the following is an example of a sex-influenced trait in humans?

Which of the following is a true statement about sex-influenced traits?

Which of the following is true about Y-linked traits in Drosophila?

Which of the following traits is termed "pseudo-autosomal"?

If a female with Coffin-Lowry syndrome has children with an unaffected male, what is the probability that a daughter will be affected?

Identify the true statement regarding the genotype of men for sex-linked genes:

In a cross between a male Drosophila with a dominant allele on the X chromosome and a female Drosophila with a recessive allele on the X chromosome, what proportion of the female offspring will express the dominant trait?

In a family with a history of hemophilia, which of the following individuals is most likely to be affected by the disorder?

The true color blind are blind to both red and green colors. Color blindness is an X-linked recessive trait. What is true about the inheritance pattern of color blindness?

Hemophilia is a rare, X-linked recessive trait. Females who carry one copy of the hemophilia gene on one of their X chromosomes are called:

Rett syndrome is caused by mutations in the MECP2 gene and follows an X-linked dominant pattern of inheritance. Which of the following statements is therefore true?

Which of the following conditions is considered X-linked?

If in females, a variant in one of the two X-chromosomes is enough to cause the disease, this condition is considered to be:

If both the mother and the father have X-linked recessive disorder, which of the following is correct?

If the father has an X-linked disease and the mother is not a carrier, which of the following is true?

The process in which the mother's egg is fertilized with the father's sperm before the nucleus (from the zygote) is removed and inserted in the donor's fertilized enucleated cell is called:

Which of the following describes homogametic sex?

Given that brown eye color in humans is completely dominant over blue color, and that a male with brown eyes carries a recessive allele (b) that causes blue eye color and a dominant allele (B) that causes brown eye color. Which of the following is incorrect regarding the children's eye color if this male weds a Bb heterozygous female?

Which of the following is the ratio of dominant epistasis?

Calico cats have at least three distinct colors in their fur, which are most frequently white, orange, and black. Calico is controlled by a sex-linked codominant allele. A female cat can have three phenotypes: black, orange, or calico, whereas male cats can be black or orange. Predict the correct ratio of kittens when a black male is crossed with an orange female.

Which of the following statements is true if allele A is epistatic to allele B?

The traits controlled by recessive genes that are linked with the X chromosome only are called "X-linked recessive traits," and such genes are called "X-linked recessive genes." What is true about X-linked recessive traits?

In fertile human females, the sex chromosomes are XX. It was noted that a human female has XY chromosomes. What is accurate about this woman?

Which of the following will have the same expression when A is the epistatic locus in dominant epistasis?

__________ is the gene interaction in which one gene masks the effect of another.

White eye color is a recessive X-linked trait in Drosophila, whereas red eye color is dominant. A red-eyed male and a white-eyed female are bred together. The probability of a female offspring with red eyes would be _______.

The ratio of red and white-eyed Drosophila when a white-eyed (recessive) male and red-eyed (dominant) female is crossed in the F2 generation is

Drosophila's white eye is a sex-linked recessive trait. What characteristics are present in the F1 generation of a cross between a male with dominant red eyes and a white-eyed female?

Which of the following best describes autosomal recessive disorder characteristics?

Which of the following hereditary diseases is not passed on from father to son?

An unaffected father and a colorblind mother had a child with Klinefelter and normal eyesight. This is because the nondisjunction occurred in _________.

The inability of one or more pairs of homologous chromosomes, also known as sister chromatids, to separate normally during meiosis is referred to as ___________.

When an organism's gene is passed on to ____________, it is said to be sex-linked.

When an unaffected mother and an unaffected father have a colorblind son and an unaffected son, who do you think carries the defective X gene?