Suppose a cell is placed in a solution with a high concentration of potassium and no sodium. How would the cellular sodium–potassium pump function in this environment? a. It would stop moving ions across the membrane. b. It would continue using ATP to pump sodium out of the cell and potassium into the cell. c. It would move sodium and potassium ions across the membrane, but no ATP would be used. d. It would reverse the direction of sodium and potassium ions to move them against their gradients.

Video transcript

Alright everyone. Let's look at our next question. It says the sodium concentration is blank inside the cell than outside and the potassium concentration is blank inside the cell to maintain these concentrations blank is needed to power up the sodium potassium pump during active transport. So before we look at our answer choices. Let's just recall briefly from our content videos um what's going on when the sodium potassium pump is working? So the sodium potassium pump facilitates active transport across the membrane of these charged particles. And for every A. T. P. Molecule used three sodium ions are moved out of the cell and two potassium my aunt's are moved into the cell so A. T. P. Is what's powering that pump. A Tv molecules are being used up so we can start by looking for that third answer. Choice and eliminating any answer that does not have A T. P. As the third answer here. So choice A. We have a TP here as the third term choice B. We don't. So choice B. We can eliminate it says protein is the third choice. So that's not our correct answer. Choice C. Has A. T. P. So that could be an answer. And choice D. Has electron. So choice D. Is not our correct answer. So now we just need to figure out what the ion concentrations are of sodium and potassium. Well let's recall that an active transport. The reason you need to consume energy is you're moving against the concentration gradient. So we're moving sodium ions out of the cell so we would expect higher sodium concentration outside the cell because we're moving them against the gradient, we're moving potassium ions into the cell. So we'd expect higher potassium ion concentration inside the cell. So let's look at our blank spots. Here we have sodium concentration is blank inside the cell while we said we'd have a higher concentration outside the cell. So I'd say it would be lower inside the cell and then potassium must be higher inside the cell and that's what it's asking us. So we'd say higher inside the cell. So let's look at our answer choices. Choice A says lower for sodium. That's correct and greater for potassium. That's correct. We wrote higher. So choice A is correct. And we'll just double check Choice C. Choice C. Says lower and lower. So it's correct for sodium but not for potassium. So choice C. Is incorrect. So again, soda. The correct answer is a sodium concentration is lower inside the cell than outside the potassium concentration is higher or greater inside the cell. To maintain these concentrations. A. T. P. Is needed to power up the sodium potassium pump during active transport. Thanks for watching See you in the next video