MCAT Biology Question 88: Answer and Explanation

Home > MCAT Test > MCAT biology practice tests

Test Information

Question: 88

13. Premature infants with respiratory distress are often placed on ventilators. Often, the ventilators are set to provide positive end-expiratory pressure. Why might this setting be useful for a premature infant?

  • A. Premature infants lack surfactant.
  • B. Premature infants lack lysozyme.
  • C. Premature infants cannot thermoregulate.
  • D. Premature infants are unable to control pH.

Correct Answer: A

Explanation:

This question requires a few different levels of thinking. The question stem states that premature infants often require ventilation using positive end-expiratory pressures. While you are not expected to know ventilator settings for the MCAT, you should be able to decode what this phrase means: at the end of expiration, the ventilator will provide a higher pressure than normal, which forces extra air into the alveoli. This pressure must be used to prevent alveolar collapse, which should remind you that surfactant serves the same purpose by reducing surface tension. Thus, it makes sense that if premature babies lack surfactant, providing extra air pressure at the end of expiration would be beneficial.

Previous       Next