A teratogenic environmental agent can cause birth defects when:

Question

A) Inherited as a recessive trait
B) Intense exposure occurs at birth
C) Disjunction occurs during meiosis
D) Exposed during early pregnancy

Answer 1

Ans: D
Feedback:
Teratogenic environmental agents cause birth defects when the fetus is exposed directly during fetal development. Recessive single-gene disorders are inherited from carriers or affected parents and are not affected by toxic agent exposures. Exposure to teratogenic agents at birth will not cause genetic defects in that infant. Disjunction during first or second meiosis is characteristic of aneuploidy disorders such as trisomy 21, Down syndrome, and is unrelated to maternal environment or in utero exposures.