Question 1

Children with PKU must avoid phenylalanine in the diet. Phenylalanine is most likely to be a component of&#10;A) fat.&#10;B) sugar.&#10;C) protein.&#10;D) carbohydrate.

Accepted Answer

Phenylalanine is an amino acid and is therefore found in protein. Children with PKU cannot adequately metabolize phenylalanine and therefore must avoid consuming protein-containing foods.

Question 2

DNA mutation is a rare event because of DNA repair mechanisms.

Accepted Answer

DNA repair mechanisms constantly monitor and correct any errors that arise during DNA replication, making mutations a rare event.

Question 3

A fetus is most vulnerable to environmental teratogens during&#10;A) birth.&#10;B) conception.&#10;C) the first trimester.&#10;D) the last trimester.

Accepted Answer

The first trimester is the period during which the fetus is most vulnerable to environmental teratogens, which are substances that can cause birth defects or other developmental abnormalities. This is because this is the period during which critical organs and systems are developing rapidly.

Question 4

A factor associated with risk of Down syndrome is&#10;A) family history of heritable diseases.&#10;B) exposure to TORCH syndrome organisms.&#10;C) maternal alcohol intake.&#10;D) maternal age.

Accepted Answer

Down syndrome is more common in babies born to mothers who are 35 years or older. Advancing maternal age increases the chances of errors in cell division that can lead to the extra chromosome present in individuals with Down syndrome. A family history of heritable diseases, exposure to TORCH syndrome organisms, and maternal alcohol intake are not considered significant risk factors for Down syndrome.

Question 5

Results of biochemical tests indicate an infant has phenylketonuria (PKU). The parents ask what PKU means. Correct responses would include all the following except&#10;A) PKU is an enzyme deficiency resulting in the inability to metabolize phenylalanine.&#10;B) PKU is an inborn error of metabolism.&#10;C) PKU results from a chromosome abnormality called nondisjunction.&#10;D) PKU is transmitted as an autosomal recessive disorder.

Accepted Answer

PKU does not result from a chromosome abnormality called nondisjunction. It is caused by a mutation in a single gene on chromosome 12, affecting the enzyme phenylalanine hydroxylase.

Question 6

Males are more likely than females to be affected by _____ disorders.&#10;A) X-linked&#10;B) autosomal dominant&#10;C) autosomal recessive&#10;D) chromosomal nondisjunction

Accepted Answer

X-linked disorders are caused by mutations on genes located on the X chromosome, and males only have one copy of the X chromosome, making them more vulnerable to X-linked disorders than females who have two copies of the X chromosome.

Question 7

Males and females are affected equally by autosomal dominant gene disorders.

Accepted Answer

Autosomal dominant gene disorders are caused by mutations on autosomal chromosomes (non-sex chromosomes) and they are equally likely to affect males and females.

Question 8

Trisomy 18 is also called Down syndrome.

Accepted Answer

Trisomy 18 is a different condition than Down syndrome, although both conditions involve an extra chromosome. Trisomy 18 is also known as Edwards syndrome.

Question 9

Characteristics of X-linked recessive disorders include which of the following?&#10;A) All daughters of affected fathers are carriers.&#10;B) Boys and girls are equally affected.&#10;C) The son of a carrier mother has a 25% chance of being affected.&#10;D) Affected fathers transmit the gene to all of their sons.

Accepted Answer

In X-linked recessive disorders, all daughters of affected fathers are carriers because they inherit the affected X chromosome from their father. Boys and girls are not equally affected, as males are more likely to express the disorder. The son of a carrier mother has a 50% chance of being affected, not 25%. Affected fathers cannot transmit the gene to their sons, as sons inherit the Y chromosome from their fathers.

Question 10

A frameshift mutation usually causes a single base pair substitution.

Accepted Answer

A frameshift mutation is caused by an insertion or deletion of a base pair(s), leading to a shift in the reading frame and altered amino acid sequence. It is not caused by a single base pair substitution.

Question 11

Genotype refers to the specific set of gene alleles an individual possesses.

Accepted Answer

The answer of Genotype refers to the specific set of...

Question 12

Most genetic mutations are not inherited and arise from new mutations during fetal development.

Accepted Answer

The answer of Most genetic mutations are not inherited and...

Question 13

What information should parents be given about the consequences of PKU?&#10;A) High dietary phenylalanine may help induce enzyme production.&#10;B) PKU is commonly associated with other congenital anomalies.&#10;C) Failure to avoid phenylalanine results in progressive mental retardation.&#10;D) Mental retardation is inevitable.

Accepted Answer

The answer of What information should parents be given about...

Question 14

Genetic diseases that follow predictable patterns of inheritance usually affect&#10;A) chromosomal structure.&#10;B) chromosomal number.&#10;C) single genes.&#10;D) sex chromosomes.

Accepted Answer

The answer of Genetic diseases that follow predictable patterns of...

Question 15

The parents of a child with PKU are concerned about the risk of transmitting the disorder in future pregnancies. What is a correct assessment of the risk?&#10;A) Each child has a 25% chance of being a carrier.&#10;B) Each child has a 25% chance of being affected.&#10;C) Since one child is already affected, the next three children will be unaffected.&#10;D) One cannot predict the risk for future pregnancies.

Accepted Answer

The answer of The parents of a child with PKU...

Question 16

A point mutation&#10;A) results from the addition or loss of one or more bases.&#10;B) is due to the translocation of a chromosomal segment.&#10;C) always produces significant dysfunction.&#10;D) involves the substitution of a single base pair.

Accepted Answer

The answer of A point mutation&#10;A) results from the addition...

Question 17

Persons with the same phenotype may have different genotypes.

Accepted Answer

The answer of Persons with the same phenotype may have...

Question 18

Polygenic disorders follow predictable patterns of inheritance.

Accepted Answer

The answer of Polygenic disorders follow predictable patterns of inheritance....

Question 19

Turner syndrome and Klinefelter syndrome are examples of sex chromosome disorders.

Accepted Answer

The answer of Turner syndrome and Klinefelter syndrome are examples...

Question 20

Recessive gene traits are expressed when an individual is homozygous for the gene.

Accepted Answer

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Question 21

Match the following descriptions with the terms below (letters may be used more than once).&#10;Trisomy 18&#10;A)Autosomal dominant&#10;B)Autosomal recessive&#10;C)X linked&#10;D)Chromosome aneuploidy

Accepted Answer