1) Which of the following statements correctly describes a Y-linked trait?
a. It can be inherited by a daughter from her father.
b. It will always be expressed if present in male individuals.
c. It will always be expressed if present in female individuals.
d. It can be inherited by a son from his mother.
2) Drosophila melanogaster is a species of fruit fly used in genetics labs due to how inexpensive they are, how visible their traits are, and their high reproductive rate.
The gene for red and white eye colour is found on the X chromosome. The allele for red eyes (XR) is dominant to the allele for white eyes (Xr).
You are asked to cross a pure breeding white-eyed female with a pure breeding red-eyed male.
What are the genotypes of the individuals involved in this cross?
1) X^R X^R
2) X^R X^r
3) X^R X^-
4) X^r X^r
5) X^R Y
6) X^r Y
Genotype of the parent male Answer
Genotype of the parent female Answer
Genotype of the male offspring Answer
Genotype of the female offspring Answer
3) A gene for eye colour in Drosophila occurs on the X chromosome. The allele for red eyes, XR, is dominant over the allele for white eyes, Xr.
A heterozygous red-eyed female fruit fly was crossed with a white-eyed male fruit fly. Complete the following Punnett square for this cross.
Answer Answer
Answer Answer Answer
Y Answer Answer
4) Marfan syndrome is an autosomal dominant disorder caused by mutations in the FBN1 gene. It affects connective tissues, commonly resulting in long bones, abnormal curvature of the spine, defects in the eye (glaucoma), and faulty heart valves.
X-linked hypophosphatemia is an X-linked dominant disorder that causes a type of rickets.
Which of the following rows describes the inheritance pattern of these disorders?
a. Marfan Syndrome
Males and females are affected with equal frequency.
X-linked Hypophosphatemia
Affected males can only pass on the trait to their daughters.
b. Marfan Syndrome
Males are affected more frequently than females.
X-linked Hypophosphatemia
Female carriers can pass on the trait to their sons.
c. Marfan Syndrome
Affected males can only pass on the trait to their daughters.
X-linked Hypophosphatemia
Males and females are affected with equal frequently.
d. Marfan Syndrome
Female carriers can pass on the trait to their sons.
X-linked Hypophosphatemia
Males are affected more frequently than females.
5) Red-green colour blindness is a sex-linked trait. Red-green colour blindness (Xrg) is the inability to distinguish between red and green colours. The Xrg allele is recessive to the normal X allele.
A normal woman has a father who has red-green colour blindness. She had a child with a man who does not have red-green colour blindness.
What is the probability they will have a son with red-green colour blindness?
a. 0
b. 0.25
c. 0.13
d. 0.50
6) Use the following information to answer the next two questions.
Hemophilia is an X-linked disorder that affects the body’s ability to create blood clots. The allele for normal blood clotting, X^H, is dominant over the allele for hemophilia, X^h.
An unaffected female that is not a carrier mated with an affected male. Which of the following rows identifies the possible genotypes of the offspring?
a. Female Male
X^H X^h X^H Y and X^h Y
b. Female Male
X^H X^H and X^H X^h X^H Y and X^h Y
c. Female Male
X^H X^h X^H Y
d. Female Male
X^H X^H and X^HX^h X^H Y
7) An unaffected daughter from the above cross married a man who does not have hemophilia.
Determine the probability of their offspring being
A daughter with hemophilia
A daughter without hemophilia
A son with hemophilia
A son without hemophilia
Express your answer as a phenotypic ratio.
Number: Answer Answer Answer Answer
Phenotype: Affected Unaffected Affected Unaffected
female female male male
8) Which of the following statements is true for sex-linked traits in birds?
a. Females can inherit an allele for a Z-linked trait only from their father, and males can inherit an allele for a Z-linked trait from either their mother or father.
b. Males can inherit an allele for a Z-linked trait only from their mother, and females can inherit an allele for a Z-linked trait from either their mother or father.
c. Both sexes can inherit an allele for a Z-linked trait from either their mother or father.
d. Females can inherit an allele for a Z-linked trait only from their father, and males can inherit an allele for a Z-linked trait only from their mother.
9) In birds, males have two Z sex chromosomes (ZZ) and females have one Z and one W sex chromosome (ZW). Since female birds have only one Z chromosome, they have only one copy of all Z-linked genes and they express the phenotype of the allele that they get.
Barred is a sex-linked dominant trait in chickens. The barring allele causes white pigment in bars on a solid color producing an alternating pattern. The original solid color in the chickens below is black.
The possible genotypes and their corresponding phenotypes are as follows:
Genotype Sex Feather Phenotype
ZBZB Male Barred
ZBZb Male Barred
ZbZb Male Black
ZBW Female Barred
ZbW Female Black
Which of the following rows correctly displays the phenotypes of the F1 generation of a cross between a pure breeding barred rooster and a black hen AND a black rooster and a barred hen, respectively?
a. Barred Male X Black Female Black Male X Barred Female
100% barred 100% barred
b. Barred X Black Female Black Male X Barred Female
100% barred Barred males and black females
c. Barred Male X Black Female Black Male X Barred Female
100% barred 2 barred females : 1 barred male : 1 black male
d. Barred Male X Black Female Black Male X Barred Female
Barred males and black females 100% barred
10) The inheritance of colour in domestic pigeons involves several genes. The dominance hierarchy of three colour alleles is ash-red > blue-black > brown (Z^A > Z^B > Z^b).
These colours are carried on the Z sex chromosome. Unlike humans, female pigeons have two different sex chromosomes (Z and W) and males have two of the same kind of sex chromosome (ZZ).
A heterozygous blue-black male pigeon mated with a brown female pigeon.
What are the expected genotypes of the offspring?
a. Z^B Z^b and Z^b W
b. Z^B Z^B,, Z^B Z^b, Z^b Z^b, Z^B W, and Z^b W
c. Z^B Z^b, Z^b Z^b, Z^B W, and Z^b W
d. Z^A Z^b, Z^B Z^b, Z^B W, and Z^A W
11)SEE IMAGE ATTACHED PLEASE ANSWER