The concentrations of two substances are increasing outside the cell.For substance A,transport into the cell increases proportionally as the concentration outside increases.For substance B transport into the cell increases but then levels off despite the concentration outside continuing to increase.What is the explanation for this?
A)Competition
B)Saturation
C)Specificity
D)Affinity

Question

Quizplus · Accepted Answer

The described phenomenon is called saturation. This occurs when all available binding sites on the cell membrane transporters for a particular substance are occupied, after which the rate of transport no longer increases proportionately with concentration outside the cell. This means that the transporter is working at maximum capacity, and any further increase in concentration outside the cell will not increase the rate of transport into the cell.

The Concentrations of Two Substances Are Increasing Outside the Cell