Question 1

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

Accepted Answer

The answer of Which disorder is characterized by the individual...

Question 2

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

Accepted Answer

The child has the genotype tt, which means he inherited a recessive allele (t) from each parent. Therefore, both parents must be carriers of the recessive allele, making them heterozygous (Tt) for the trait.

Question 3

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

Accepted Answer

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

Question 4

Which disorder is the most common chromosome anomaly among newborns?

Accepted Answer

Down syndrome, also known as Trisomy 21, is the most common chromosome anomaly among newborns, affecting approximately 1 in every 700 babies born in the US. Turner syndrome, Klinefelter syndrome, Trisomy X, and XYY syndrome are all much rarer than Down syndrome.

Question 5

Sickle- cell anemia is caused by a

Accepted Answer

Sickle-cell anemia is caused by a mutation in the HBB gene on chromosome 11, which is a recessive autosomal gene.

Question 6

For which disorder can those affected be male or female?

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 7

The failure of chromosomes to segregate properly during meiosis is called

Accepted Answer

Nondisjunction is the failure of chromosomes to segregate properly during meiosis. This can lead to aneuploidy, which is a condition in which an organism has an abnormal number of chromosomes.

Question 8

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?

Accepted Answer

A woman with blood type AB can pass either A or B alleles, and a man with blood type O can only pass O alleles. Therefore, their biological children can only have blood types A (AO) or B (BO). The child with blood type O (OO) must be adopted.

Question 9

Only males can express sex- linked traits.

Accepted Answer

Both males and females can express sex-linked traits, but females need two copies of the recessive allele to express the trait, while males only need one. This is because males have only one X chromosome, while females have two.

Question 10

Autosomal nondisjunction can result in

Accepted Answer

The answer of Autosomal nondisjunction can result in
...

Question 11

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

Accepted Answer

Down syndrome is more common among the babies of older mothers, with the risk increasing as the mother's age at conception increases.

Question 12

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

Accepted Answer

Down syndrome, also known as Trisomy 21, is the most common chromosomal disorder among live-born infants.

Question 13

What is the difference between phenotype and genotype?

Accepted Answer

Phenotype refers to the observable characteristics or traits of an organism, while genotype refers to the genetic makeup or combination of alleles that an organism carries.

Question 14

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

Accepted Answer

Pedigree analysis is not exclusively used for studying inheritance patterns in dogs; it is used for studying inheritance patterns in humans and other organisms as well.

Question 15

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

Accepted Answer

Heterozygotes for the sickle-cell allele have a selective advantage in malaria-endemic regions because they have some resistance to malaria, which is prevalent in many parts of Africa.

Question 16

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?

Accepted Answer

Incomplete dominance is the inheritance pattern where the phenotype of the heterozygote is intermediate between the homozygous dominant and homozygous recessive phenotype. In sickle-cell anemia, the heterozygote individuals have a mix of normal and sickle-shaped red blood cells, exhibiting incomplete dominance.

Question 17

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

Accepted Answer

While green peas may be more commonly found in stores, yellow pea color is dominant over green pea color in genetic inheritance. This means that if a pea plant with yellow pea color is crossed with a pea plant with green pea color, the resulting offspring are more likely to have yellow pea color. However, there may be other factors involved in why green peas are more commonly found in stores, such as taste or market demand.

Question 18

Which disorder is characterized by an abnormal number of autosomes?

Accepted Answer

Down syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of an extra copy of chromosome 21.

Question 19

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

Accepted Answer

Down syndrome is caused by nondisjunction of chromosome 21, resulting in a trisomy 21 child.

Question 20

Females always inherit sex- linked traits from their mothers.

Accepted Answer

Females can inherit sex-linked traits from both their mother and father. However, males only inherit sex-linked traits from their mother as they receive a Y chromosome from their father which does not carry any sex-linked genes.

Quiz 11: Patterns of Inheritance