Early Influences on Development – Prenatal Development Flashcards
Phenylketonuria (PKU) is an:
A. autosomal dominant disorder.
B. autosomal recessive disorder.
C. X-linked dominant disorder.
D. X-linked recessive disorder.
Answer B is correct. PKU is an autosomal recessive trait which means that, to have PKU, a person must inherit the recessive gene from both parents. (An autosomal disorder is carried on an autosome, which is any chromosome that is not X-linked; an X-linked disorder is carried on a sex chromosome.)
A fetus typically achieves the age of viability between ________ weeks after conception.
A. 16 and 20
B. 18 and 20
C. 20 and 22
D. 22 and 26
Answer D is correct. Although the age of viability reported by different experts varies somewhat, most agree that it’s between 22 and 26 weeks after conception.
Rett syndrome (which is also referred to as RTT) is usually caused by:
A. the absence of an entire or partial X chromosome.
B. a mutated gene on an X chromosome.
C. a deletion on a maternal chromosome.
D. a deletion on a paternal chromosome.
Answer B is correct. Rett syndrome is an X-linked dominant disorder that is most often caused by mutations in the MECP2 gene.
Which of the following types of Down Syndrome can be caused by an error during cell division and by heredity?
A. translocation trisomy 21
B. mosaic trisomy 21
C. standard trisomy 21
D. all of the above
Answer A is correct. Unlike mosaic and standard trisomy 21, which are both caused by an error during cell division, translocation trisomy 21 can be caused by an error during cell division or heredity.
Klinefelter syndrome is caused by which of the following?
A. the presence of an extra Y chromosome
B. the absence of a Y chromosome
C. the presence of an extra X chromosome
D. the absence of an X chromosome
Answer C is correct. Klinefelter syndrome affects males and is caused by the presence of two or more X chromosomes in addition to a single Y chromosome.
The symptoms of fetal alcohol spectrum disorder are:
A. largely reversible with early behavioral interventions.
B. largely reversible with early nutritional and behavioral interventions.
C. largely reversible if exposure to alcohol was limited to the third trimester.
D. largely irreversible.
Answer D is correct. The severity and nature of the symptoms of the fetal alcohol spectrum disorders vary, but most symptoms are irreversible.
Exposure to a teratogen during which period of prenatal development is most likely to cause major birth defects:
A. zygote
B. embryonic
C. germinal
D. fetal
Answer B is correct. The three periods of prenatal development are, in order, germinal, embryonic, and fetal. Major birth defects are most likely to occur when organs and structures are forming most rapidly, which occurs during the embryonic period. The zygote period (answer A) is another name for the germinal period.
Recent data collected by the National Center for Health Statistics indicate that the preterm birthrate is highest for __________ mothers.
A. non-Hispanic Black
B. non-Hispanic White
C. non-Hispanic Asian
D. Hispanic
Answer A is correct. Data collected by the National Center for Health Statistics indicate that, since 1981, preterm (and low birthweight) rates have been consistently highest for non-Hispanic Black mothers.
Prader-Willi and Angelman syndromes are both caused by:
A. two recessive genes.
B. a chromosomal deletion.
C. a missing sex chromosome.
D. an extra sex chromosome.
Answer B is correct. Both of these disorders are due to a chromosomal deletion, which occurs when part of a chromosome is missing. Prader-Willi syndrome is caused by a deletion on paternal chromosome 15, while Angelman syndrome is caused by a deletion on maternal chromosome 15.
