Question 1

Information parents should be given about the consequences of PKU includes&#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

Failure to avoid phenylalanine results in progressive mental retardation.Phenylketonuria (PKU)results from an inability to metabolize the amino acid phenylalanine because of lack of the enzyme phenylalanine hydroxylase.Intake of phenylalanine will not help induce enzyme production.This disorder is not necessarily associated with other congenital anomalies.Mental retardation can be prevented or lessened with avoidance of phenylalanine.

Question 2

Characteristics of X-linked (sex-linked)recessive disorders include&#10;A) all daughters of affected fathers' being carriers.&#10;B) boys' and girls' being equally affected.&#10;C) the son of a carrier female's having a 25% chance of being affected.&#10;D) affected fathers' transmitting the gene to all their sons.

Accepted Answer

All daughters of affected fathers are carriers.X-linked (sex-linked)disorders affect primarily males.A carrier female has a 1 in 2 chance of producing an affected son.Affected fathers transmit the defective gene to none of their sons but to all their daughters.

Question 3

Characteristics of Marfan syndrome include that it (Select all that apply.)&#10;A) is a single-gene disorder.&#10;B) involves alterations in connective tissue.&#10;C) leads to skeletal and joint deformities.&#10;D) leads to short stocky build.&#10;E) results in dangerous cardiovascular disorders.

Accepted Answer

Marfan syndrome is a single-gene disorder that involves alterations in connective tissue and leads to skeletal and joint deformities.The aorta weakens and may rupture and cardiac valves may malfunction.Individuals with Marfan syndrome are typically tall and slender,with long,thin arms and legs,rather than short and stocky.

Question 4

Huntington disease primarily affects the _____ system.&#10;A) neurologic&#10;B) muscular&#10;C) gastrointestinal&#10;D) endocrine

Accepted Answer

Huntington disease primarily affects the neurologic system and leads to uncontrolled movement of the extremities.Huntington disease does not primarily affect the muscles,although the altered neural involvement secondarily causes involuntary movement of the arms and legs.It also does not affect the gastrointestinal and endocrine systems.

Question 5

The primary factor associated with the 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

Advanced maternal age is associated with Down syndrome in the most common form of the disease.A family history of heritable disease is not the primary factor and occurs in only 4% of cases.Exposure to TORCH syndrome organisms is not a risk factor for Down syndrome.Maternal alcohol intake is not a risk factor for Down syndrome.

Question 6

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

Between the third and ninth week of gestation,the embryo is very vulnerable to teratogenesis,with the fourth and fifth week being the time of peak susceptibility.By birth,fetal development is complete and not vulnerable to environmental teratogens.Prior to the third week of gestation,either exposure to a teratogen generally damages so few cells that the embryo develops normally,or spontaneous abortion occurs because of major cell damage.Fetal insults occurring after the third month are more likely to result in growth retardation or injury to normally formed organs.

Question 7

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 found in protein.Most fats,sugars,and carbohydrates do not contain phenylalanine.

Question 8

Huntington disease is often transferred to offspring before a parent knows of the genetic possibility of this disease,because&#10;A) symptoms are so mild that they are not recognized.&#10;B) symptoms often do not occur until approximately 40 years of age.&#10;C) genetic testing for the disease is not possible.&#10;D) the genetic alteration is rarely expressed.

Accepted Answer

Signs of mental deterioration and involuntary muscle movements do not appear until approximately age 40.The delayed onset means the parent may transmit the disorder to offspring before he or she knows they have the disorder.Symptoms of Huntington's disease are not necessarily mild,and are not the reason for delayed identification of the genetic susceptibility.Genetic testing for the disease is possible.The genetic alteration is expressed if the triplet repeats are greater than 40.

Question 9

The risk period for maternal rubella infection leading to congenital problems begins&#10;A) prior to conception.&#10;B) during the last trimester.&#10;C) at birth.&#10;D) all through pregnancy.

Accepted Answer

The risk period for maternal rubella infection begins prior to conception and extends to 20 weeks' gestation,after which the virus rarely crosses the placenta.The virus rarely crosses the placenta after 20 weeks' gestation.The virus does not cross the placenta at birth and would not cause congenital problems at this point.The risk period for maternal rubella infection begins prior to conception and extends to 20 weeks' gestation,after which the virus rarely crosses the placenta.

Question 10

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

Accepted Answer

A point mutation involves a single base pair substitution.A point mutation does not result from the addition or loss of bases,or from translocation of a chromosomal segment,but rather from a substitution.The inclusion of the abnormal amino acid in the sequence of the protein as a result of a point mutation may or may not be of clinical significance.

Question 11

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

The answer of Males are more likely than females to...

Question 12

The parents of a child with PKU are concerned about the risk of transmitting the disorder in future pregnancies.The correct assessment of the risk is&#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 13

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

Accepted Answer

The answer of Results of biochemical tests indicate an infant...

Question 14

Cystic fibrosis is a single-gene disorder that primarily affects&#10;A) brain and heart.&#10;B) kidney and adrenals.&#10;C) lungs and pancreas.&#10;D) liver and intestine.

Accepted Answer

The answer of Cystic fibrosis is a single-gene disorder that...

Deck 6: Genetic and Developmental Disorders