Which of the Following is an Example of Nondisjunction

Question

Which of the following is an example of nondisjunction?
A) Fetal alcohol syndrome
B) Spina bifida secondary to maternal infection with rubella
C) Down syndrome
D) Twinning

Accepted Answer

Nondisjunction occurs when chromosomes fail to separate properly during cell division, resulting in an abnormal number of chromosomes in the daughter cells. Down syndrome, also known as trisomy 21, is caused by nondisjunction of chromosome 21, resulting in an individual having three copies of this chromosome instead of the normal two. Fetal alcohol syndrome is caused by exposure to alcohol during fetal development, spina bifida is caused by incomplete neural tube closure during fetal development, and twinning is a natural occurrence during early embryonic development and not related to nondisjunction.