Chapter 6: Genetic and Developmental Disorders

Chapter 6: Genetic and Developmental Disorders

Complete Chapter Questions With Answers

Sample Questions Are Posted Below

MULTIPLE CHOICE

1. Characteristics of X-linked (sex-linked) recessive disorders include

ANS:  A

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.

REF:   Pg. 103

2. A fetus is most vulnerable to environmental teratogens during

ANS:  C

Between the third and ninth week of gestation, the embryo is very vulnerable to teratogenesis, with the fourth and fifth weeks’ 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 due to major cell damage. Fetal insults occurring after the third month are more likely to result in growth retardation or injury to normally formed organs.

REF:   Pg. 108

3. 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

ANS:  C

PKU is not a chromosome abnormality, but instead a single-gene abnormality often referred to as inborn errors of metabolism. The other answer choices are true statements regarding PKU.

REF:   Pgs. 100-103

4. 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

ANS:  B

As an autosomal recessive disorder, the mating of two carriers (heterozygous) results in a 1 in 4 chance of producing an affected offspring and a 2 in 4 chance of producing an offspring who carries the disease. The mating of two carriers (heterozygous) results in a 2 in 4 chance of producing an offspring who carries the disease. The mating of two carriers (heterozygous) results in a 1 in 4 chance of producing an affected offspring and a 2 in 4 chance of producing an offspring who carries the disease. One can predict the risk of future pregnancies.

REF:   Pgs. 101-103