MCAT Biology Question — Red Blood Cell
- Aug 12, 2014
- MCAT Question of the Day
a) osmotic pressure pulls water through the membrane to the interior of the cell.
b) the electrochemical gradient favors the inside of the RBC.
c) non-polar molecules cross the cell membrane into the water down their concentration gradient.
d) solute molecules rapidly diffuse into the water exterior to the RBC.
A red blood cell (RBC) placed in distilled water will burst because the osmotic pressure causes a rapid influx of water. In fact, so much water will enter the cell that the RBC will burst. This is an extreme case of the RBC being placed in a severely hypotonic solution. Conversely, when placed in hypertonic solution, the RBC will shrivel as water diffuses out.
a) osmotic pressure pulls water through the membrane to the interior of the cell. Correct.
b) the electrochemical gradient favors the inside of the RBC. Incorrect, Osmolarity, osmotic pressure, and water diffusion have nothing to do with the electrochemical gradient.
c) non-polar molecules cross the cell membrane into the water down their concentration gradient. Incorrect, water diffuses across the cell membrane to cause the cell to burst. If solutes crossed the membrane to create an isotonic environment, the cell would not burst.
d) solute molecules rapidly diffuse into the water exterior to the RBC. Incorrect, See explanation c).
Want more MCAT practice?
We’ve got options for every schedule and learning style!
From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
Search the Blog
Free ConsultationSchedule Now
MCAT Blog How to Review MCAT Full-Lengths
Free MCAT Practice AccountNeed great MCAT practice?
Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.Learn More