Question 1

Huntington's disease is a late-onset autosomal dominant disorder.What is the chance that a heterozygous woman with the disease will pass the affected allele on to her children?  
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

Accepted Answer

Since Huntington's disease is an autosomal dominant disorder and the woman is heterozygous, she has one affected allele and one normal allele. With each pregnancy, there is a 50% chance that she will pass on the affected allele to her child. Therefore, the chance that she will pass the affected allele on to her children is 50%.

Question 2

A father who has red-green color blindness and a mother who has normal vision may have the following child:  
A) Color blind male child
B) Color blind female child
C) Normal vision male child only
D) Normal vision female child only.
E) Normal vision male or female child.

Accepted Answer

Color blindness is a sex-linked disorder and is carried on the X chromosome. Since females have two X chromosomes, if the mother is a carrier of the color blindness gene (despite having normal vision), she can pass on the gene to her son without being affected by the disorder herself. However, if the father has color blindness and passes on his affected X chromosome to his son, then the son will have color blindness. As for daughters, they need both X chromosomes to carry the color blindness gene to be affected. In this case, the father can only pass on his Y chromosome to his daughters, so they will not be affected by the disorder. Therefore, there is a 50% chance of having a color blind male child and a 50% chance of having a normal vision male or female child.

Question 3

In humans,an X-linked disorder called coloboma iridia (a fissure in the iris)is a recessive trait.A normal couple has an afflicted daughter.What would be the most plausible scenario for this situation?  
A) The mother carries two recessive alleles.
B) The father carries one recessive allele, and the mother carries one recessive allele.
C) The female is not the biological mother, but the male is the biological father.
D) The male is not the biological father, but the female is the biological mother.
E) Both parents are heterozygous for the trait.

Accepted Answer

The answer of In humans,an X-linked disorder called coloboma iridia...

Question 4

An X-linked recessive gene (c)produces red-green color blindness.A normal woman whose father was color blind marries a color-blind man.What are the chances that the first son will be color blind?  
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

Accepted Answer

Since the woman is normal, she has two X chromosomes that are both carrying a normal allele (C). However, since her father was color blind, he had at least one affected X chromosome, which he could have passed to his daughter. Thus, there is a 50% chance that the woman is a carrier (heterozygous: XcX or XCX). The father is color blind and must carry an affected X chromosome (XcY). When the couple has a son, he has a 50% chance of inheriting the mother's X chromosome with the normal allele (XC) and a 50% chance of inheriting her X chromosome with the recessive, color-blindness allele (Xc). If he inherits the latter, he will be color blind since he doesn't have a normal allele to mask the effect of the recessive allele. Therefore, the chance that their first son will be color blind is 50%.

Question 5

Color blindness is an X-linked recessive trait.Two normal-vision parents produce a color-blind child.The child's sex is _____________.

Accepted Answer

The answer of Color blindness is an X-linked recessive trait.Two...

Question 6

Some autosomal dominant diseases do not run in the family because they are lethal before the affected individual can __________.

Accepted Answer

The answer of Some autosomal dominant diseases do not run...

Question 7

A mother expresses the symptoms for Huntington's disease,an autosomal dominant trait.What are the chances that her offspring would carry a mutated allele if her partner is unaffected by the disease?  
A) 0-25%
B) 25-50%
C) 50-100%
D) 75%
E) 100%

Accepted Answer

Huntington's disease is an autosomal dominant disorder, meaning only one copy of the mutated allele is needed for the trait to be expressed. If the mother has the disease, she has one mutated allele and one normal allele. The unaffected father has two normal alleles. Each child has a 50% chance of inheriting the mutated allele from the mother.

Question 8

Select the disorder that best matches each the following statements.
-This disorder is an X-linked recessive trait.
A)Tay-Sachs disease
B)Turner syndrome
C)Progeria
D)Hemophilia A
E)Down syndrome

Accepted Answer

Hemophilia A is an X-linked recessive disorder, meaning it is caused by a gene mutation on the X chromosome and is more commonly seen in males.

A) Tay-Sachs disease is an autosomal recessive disorder, not X-linked.
B) Turner syndrome is not X-linked, but rather a chromosomal disorder where an individual only has one X chromosome and no Y chromosome.
C) Progeria is a rare genetic disorder caused by a mutation in the LMNA gene, and is not X-linked.
E) Down syndrome is caused by a chromosomal abnormality, typically having an extra copy of chromosome 21, and is not X-linked.

Question 9

Select the disorder that best matches each the following statements.
-This disorder is due to a sex chromosome abnormality probably caused by nondisjunction of sex chromosomes at meiosis.
A)Tay-Sachs disease
B)Turner syndrome
C)Progeria
D)Hemophilia A
E)Down syndrome

Accepted Answer

Turner syndrome is caused by an absence or abnormality of one of the X chromosomes, often due to nondisjunction during meiosis. This leads to a deficiency of certain hormones, resulting in physical and developmental abnormalities.

Question 10

Hemophilia is caused by an X-linked recessive gene.A normal woman whose father had hemophilia marries a normal man.What are the chances of hemophilia in their children?  
A) All females would be normal.
B) All females would be carriers.
C) All males would have hemophilia.
D) All females would have hemophilia.
E) Half of the women would have hemophilia.

Accepted Answer

The woman is a carrier (XHXh) because her father had hemophilia (XhY). She can pass the hemophilia gene to her sons, but her daughters will be carriers, not affected, because they will inherit a normal X from their father.

Question 11

Select the disorder that best matches each the following statements.
-This disorder is also known as trisomy 21.
A)Tay-Sachs disease
B)Turner syndrome
C)Progeria
D)Hemophilia A
E)Down syndrome

Accepted Answer

Down syndrome is also known as trisomy 21, as it is caused by an extra copy of chromosome 21. Tay-Sachs disease is caused by a deficiency in an enzyme called hexosaminidase A, Turner syndrome involves a missing or partially missing X chromosome, Progeria is a rare genetic disorder that causes premature aging, and Hemophilia A is a bleeding disorder caused by a deficiency in clotting factor VIII.

Question 12

Duchenne muscular dystrophy (DMD),a recessive condition,most commonly occurs in boys.This pattern of inheritance is ________________.

Accepted Answer

The answer of Duchenne muscular dystrophy (DMD),a recessive condition,most commonly...

Question 13

Red-green color blindness is an X-linked recessive trait (dominant allele denoted as C).Two normal-vision parents have a color-blind son.The genotypes of the father,mother,and son are respectively _____,_____,_____.

Accepted Answer

The answer of Red-green color blindness is an X-linked recessive...

Question 14

In humans,which genetic mechanism led to the formation of the X and Y chromosomes?  
A) Translocation
B) Nondisjunction
C) Inversion
D) Reduced crossing over
E) Insertion

Accepted Answer

Reduced crossing over between the X and Y chromosomes over evolutionary time has led to their differentiation and the formation of distinct sex chromosomes. This limited recombination allowed for the divergence in size and gene content between the X and Y chromosomes.

Question 15

Select the disorder that best matches each the following statements.
-This disorder is an autosomal recessive disorder that results in the body's inability to break down lipids.
A)Tay-Sachs disease
B)Turner syndrome
C)Progeria
D)Hemophilia A
E)Down syndrome

Accepted Answer

Tay-Sachs disease is an autosomal recessive disorder that results in the body's inability to break down lipids, specifically a type of fat called ganglioside GM2. This leads to the accumulation of ganglioside GM2 in the brain and nervous system, causing progressive damage and symptoms including developmental delay, loss of motor skills, blindness, and seizures. It usually presents within the first few months of life and has a very poor prognosis. There is currently no cure for Tay-Sachs disease.

Question 16

Which nondisjunction disorder must be due to an event in sperm development?  
A) XO
B) XXX
C) XXY
D) XYY
E) Trisomy 21

Accepted Answer

XYY syndrome must result from nondisjunction during sperm development because an extra Y chromosome can only come from the father. Females (XX) cannot contribute a Y chromosome.

Quiz 14: Chromosomes and Human Inheritance

Huntington's disease is a late-onset autosomal dominant disorder.What is the chance that a heterozygous woman with the disease will pass the affected allele on to her children?

A father who has red-green color blindness and a mother who has normal vision may have the following child:

In humans,an X-linked disorder called coloboma iridia (a fissure in the iris) is a recessive trait.A normal couple has an afflicted daughter.What would be the most plausible scenario for this situation?

An X-linked recessive gene (c) produces red-green color blindness.A normal woman whose father was color blind marries a color-blind man.What are the chances that the first son will be color blind?

Color blindness is an X-linked recessive trait.Two normal-vision parents produce a color-blind child.The child's sex is _____________.

Some autosomal dominant diseases do not run in the family because they are lethal before the affected individual can __________.

A mother expresses the symptoms for Huntington's disease,an autosomal dominant trait.What are the chances that her offspring would carry a mutated allele if her partner is unaffected by the disease?

Select the disorder that best matches each the following statements. -This disorder is an X-linked recessive trait.

Select the disorder that best matches each the following statements. -This disorder is due to a sex chromosome abnormality probably caused by nondisjunction of sex chromosomes at meiosis.

Hemophilia is caused by an X-linked recessive gene.A normal woman whose father had hemophilia marries a normal man.What are the chances of hemophilia in their children?

Select the disorder that best matches each the following statements. -This disorder is also known as trisomy 21.

Duchenne muscular dystrophy (DMD),a recessive condition,most commonly occurs in boys.This pattern of inheritance is ________________.

Red-green color blindness is an X-linked recessive trait (dominant allele denoted as C).Two normal-vision parents have a color-blind son.The genotypes of the father,mother,and son are respectively ___,_,___.

In humans,which genetic mechanism led to the formation of the X and Y chromosomes?

Select the disorder that best matches each the following statements. -This disorder is an autosomal recessive disorder that results in the body's inability to break down lipids.

Which nondisjunction disorder must be due to an event in sperm development?