Question 1

Which of the following is the most common chromosome disorder among live -born infants?
A) Down syndrome
B) Klinefelter syndrome
C) Turner syndrome
D) Trisomy X

Accepted Answer

Down syndrome, also known as trisomy 21, is the most common chromosome disorder among live-born infants. It occurs when an individual has a full or partial extra copy of chromosome 21. This additional genetic material alters the course of development and causes the characteristics associated with Down syndrome.

Question 2

Which of the following conditions may cause infertility in a human?
A) XXY
B) XY
C) XX
D) XYY
E) XXX

Accepted Answer

The answer of Which of the following conditions may cause...

Question 3

What is the reason for the prevalence of the sickle-cell allele in African populations?
A) Sickled cells are better able to clot blood.
B) African populations tend to be at higher altitudes, and sickled cells better bind oxygen in these environments.
C) Heterozygotes have some resistance to the parasite that causes malaria.
D) Sickled cells help prevent vitamin A deficiency among African populations.

Accepted Answer

Heterozygotes for the sickle-cell allele (carrying one copy of the sickle-cell gene and one normal hemoglobin gene) have a resistance to malaria, a disease caused by the Plasmodium parasite. This advantage has led to the prevalence of the sickle-cell allele in regions where malaria is common, such as parts of Africa.

Question 4

Yellow pea color is dominant over green pea color, despite the observation that most store-bought, edible peas are green.

Accepted Answer

Yellow pea color is dominant over green pea color according to Mendelian genetics, but green peas are more commonly found in stores because they are harvested earlier for sweetness, and the green color is preferred for culinary uses.

Question 5

Which disorder is the most common chromosome anomaly among newborns?
A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Accepted Answer

Down syndrome, also known as trisomy 21, is the most common chromosome anomaly among newborns. It occurs when an individual has a full or partial extra copy of chromosome 21. This additional genetic material alters the course of development and causes the characteristics associated with Down syndrome.

Question 6

Which disorder is characterized by an abnormal number of autosomes?
A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Accepted Answer

Down syndrome is characterized by an extra copy of chromosome 21, making it an autosomal disorder. The other options involve sex chromosomes, not autosomes.

Question 7

Only males can express sex-linked traits.

Accepted Answer

Sex-linked traits can be expressed by both males and females, but the patterns of inheritance and expression can differ due to the differences in sex chromosomes (X and Y) between males (XY) and females (XX).

Question 8

Females always inherit sex-linked traits from their mothers.

Accepted Answer

Females inherit one X chromosome from their mother and one X chromosome from their father, so they can inherit sex-linked traits from either parent.

Question 9

Sickle-cell anemia is caused by a recessive mutation in the hemoglobin gene. However, heterozygote individuals also show a small percentage of sickled red blood cells. What type of inheritance pattern is this an example of?
A) Polygenic inheritance
B) Sex linked
C) Chromosomal nondisjunction
D) Incomplete dominance

Accepted Answer

This is an example of incomplete dominance because heterozygous individuals (carriers of the sickle-cell trait) exhibit a phenotype that is not as severe as those with two copies of the mutated gene, but still show some symptoms (a small percentage of sickled cells), indicating that neither allele is completely dominant over the other.

Question 10

The failure of chromosomes to segregate properly during meiosis is called
A) inversion.
B) translocation.
C) replication.
D) independent assortment.
E) nondisjunction.

Accepted Answer

Nondisjunction is the failure of chromosomes to segregate properly during meiosis, leading to gametes with an abnormal number of chromosomes.

Question 11

For which disorder can those affected be male or female?
A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Accepted Answer

Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is not linked to sex chromosomes and therefore can affect both males and females.

Question 12

Autosomal nondisjunction can result in
A) Down syndrome.
B) XYY males.
C) trisomy X.
D) Klinefelter syndrome.
E) Turner syndrome.

Accepted Answer

Autosomal nondisjunction refers to the failure of autosomes (non-sex chromosomes) to separate properly during cell division, leading to conditions like Down syndrome, which is caused by an extra copy of chromosome 21. The other conditions listed are related to nondisjunction of sex chromosomes.

Question 13

What is the difference between phenotype and genotype?
A) Phenotype is when both alleles are the same and genotype is when the alleles are different.
B) Genotype is the physical expression of a trait and phenotype is the combination of alleles carried by the organism.
C) Phenotype is the physical expression of a trait and genotype is the combination of alleles carried by the organism.
D) Phenotype is the alleles that are hidden and genotype is the alleles that are expressed.

Accepted Answer

Phenotype refers to the observable characteristics or traits of an organism, such as its height, eye color, or blood type, which result from the interaction of its genotype (the genetic makeup) with the environment. Genotype, on the other hand, is the set of genes in our DNA which is responsible for a particular trait.

Question 14

Sickle-cell anemia is caused by a
A) recessive autosomal gene.
B) recessive sex-linked gene.
C) dominant autosomal gene.
D) combined interaction of several genes.
E) simple dominant gene.

Accepted Answer

Sickle-cell anemia is caused by a mutation in the hemoglobin gene, which is autosomal (located on a non-sex chromosome) and recessive, meaning two copies of the mutated gene are needed for the disease to manifest.

Question 15

Which disorder is characterized by the individual having a normal number of sex chromosomes?
A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Accepted Answer

Down syndrome is characterized by an extra chromosome 21, not involving sex chromosomes, while the other options involve abnormalities in the number of sex chromosomes.

Question 16

All of the following are true regarding pedigree analysis EXCEPT that it
A) documents the transmission of a genetic characteristic over two or more generations.
B) can incorporate molecular biology techniques.
C) is exclusively used to study the patterns of inheritance in dogs.
D) reveals whether a trait is dominant or recessive.

Accepted Answer

Pedigree analysis is not exclusively used to study the patterns of inheritance in dogs; it is a tool used in genetics to track the inheritance of specific traits in humans and many other species as well.

Question 17

A child is born with dwarfism (tt). His parents are of normal height. Which of the following must be TRUE of the parents?
A) They are both homozygous recessive dwarf.
B) They are both heterozygous tall.
C) They are both heterozygous dwarf.
D) They are both homozygous dominant tall.

Accepted Answer

Since the child has dwarfism and is homozygous recessive (tt), each parent must have contributed one recessive allele (t). This means both parents are carriers of the dwarfism allele but do not express the trait themselves, indicating they are heterozygous tall (Tt).

Question 18

A disorder caused by nondisjunction of chromosome 21, resulting in a trisomy 21 child, is
A) color deficiency.
B) Down syndrome.
C) cystic fibrosis.
D) hemophilia.

Accepted Answer

Down syndrome is caused by the presence of an extra copy of chromosome 21, a condition known as trisomy 21, which results from nondisjunction during cell division.

Question 19

A woman with blood type AB and a man with blood type O have three children, one of whom is adopted. The blood types of the children are A, B, and O. What is the blood type of the adopted child?
A) A
B) O
C) B
D) Not enough information is provided to answer this question.

Accepted Answer

A person with blood type AB can only pass on A or B alleles to their offspring, and a person with blood type O can only pass on O alleles. Therefore, their biological children can only have blood types A or B, making the child with blood type O the adopted one.

Question 20

Which disorder is more common among the babies of older mothers?
A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Accepted Answer

Down syndrome is more common among babies born to older mothers. The risk of having a baby with Down syndrome increases with the mother's age, particularly after age 35.

Quiz 11: Patterns of Inheritance

Which of the following is the most common chromosome disorder among live -born infants?

Which of the following conditions may cause infertility in a human?

What is the reason for the prevalence of the sickle-cell allele in African populations?

Yellow pea color is dominant over green pea color, despite the observation that most store-bought, edible peas are green.

Which disorder is the most common chromosome anomaly among newborns?

Which disorder is characterized by an abnormal number of autosomes?

Only males can express sex-linked traits.

Females always inherit sex-linked traits from their mothers.

Sickle-cell anemia is caused by a recessive mutation in the hemoglobin gene. However, heterozygote individuals also show a small percentage of sickled red blood cells. What type of inheritance pattern is this an example of?

The failure of chromosomes to segregate properly during meiosis is called

For which disorder can those affected be male or female?

Autosomal nondisjunction can result in

What is the difference between phenotype and genotype?

Sickle-cell anemia is caused by a

Which disorder is characterized by the individual having a normal number of sex chromosomes?

All of the following are true regarding pedigree analysis EXCEPT that it

A child is born with dwarfism (tt) . His parents are of normal height. Which of the following must be TRUE of the parents?

A disorder caused by nondisjunction of chromosome 21, resulting in a trisomy 21 child, is

A woman with blood type AB and a man with blood type O have three children, one of whom is adopted. The blood types of the children are A, B, and O. What is the blood type of the adopted child?

Which disorder is more common among the babies of older mothers?