MCAT Biology Question 44: Answer and Explanation

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Question: 44

14. A pregnant women is accidentally given a single dose of a teratogenic drug late in the third trimester. The baby is born three days later. Which of the following is the most likely outcome?

  • A. Complete failure of organ development and death of the fetus
  • B. Partial failure of organ development with survival of the fetus
  • C. Serious disfigurement of the fetus
  • D. Respiratory distress at birth, but no long-term effects

Correct Answer: D

Explanation:

The question stem states that the pregnant woman was given the drug three days before the baby was born. It is important to remember that organogenesis occurs during the first trimester. The last structure to become fully functional is the lungs. Because the organs were already largely formed prior to the administration of the teratogenic drug, it is likely that there was no major effect on the development of any organ as a result of exposure to the teratogen, eliminating choices (A), (B), and (C). However, because lung tissues are so sensitive and because they mature so late, it is likely that the infant may have some respiratory distress at birth.

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