A Fellow Student Is Studying Graded Potentials and Decides That

question 49

Multiple Choice

A fellow student is studying graded potentials and decides that any time K⁺ is involved, the potential must be hyperpolarizing. Which of the following arguments could accurately explain that the ion alone doesn't determine this?

• A) Ions move based on an electrochemical gradient. If the concentration of K⁺ outside the cell is greatly increased, then it would move in, depolarizing the cell.
• B) When an ion crosses the membrane, it brings its charge with it. Because K⁺ is positively charged, it can only depolarize a cell (make it less negative.)
• C) K⁺ basically doesn't move across the membrane unless it is actively transported, and potentials involve the movement of ions through channels.
• D) Many types of ions (with their charges) are located inside and outside the cell. It is the concentrations of those other ions that determines whether a channel opening will lead to a depolarizing or hyperpolarizing potential.

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