Hi guys, could someone please help me understand question 11 muilti-choice from the 2014 exam?
I get why it's D but I'm not exactly sure what the problem is with A.
I asked my teacher and they said it's because we're not concerned with the movement of the potassium ions, just the water molecules which move via osmosis. So from what I understood, that meant that the potassium ions weren't actually moving in and out of the motor cells, only the water was, which affected the concentration inside the cell BUT the question specifies that the "potassium ions stream out of the cell through ion channels" so doesn't that mean it's moving? So I also asked about this and she mentioned the potassium pump (which I'm so confused about) and how that means that it is active transport. HOWEVER (sorry), the question also states that when the cell is turgid, the concentration of potassium ions inside the cell is higher than outside the cell so wouldn't that mean that the ions would be moving along their concentration gradient when they move out, making it not active transport? Or is the definition of active transport not restricted to the concentration gradient?
I hope that makes sense! Sorry for the long read. I would be ETERNALLY grateful for any explanations (diagrams are also very very welcome because this question is so confusing)
Thank you in advance!