Final answer:
In a hypothetical cell with a membrane permeable only to K+, potassium ions would diffuse out of the cell until the Coulomb force balances the concentration gradient, establishing a voltage across the membrane and contributing to the resting membrane potential.
Step-by-step explanation:
The question we are examining involves understanding what would happen in a hypothetical cell with a membrane permeable only to K+ (potassium ions). In normal physiological conditions, a cell membrane is semipermeable, allowing certain ions to pass through while blocking others. In the resting state of a neuron, for instance, the membrane is permeable to K+ and Cl- but impermeable to Na+ (sodium ions). If a cell's membrane were exclusively permeable to K+, diffusion would lead to the movement of K+ from a region of high concentration to one of low concentration, with the potassium ions moving outward until the electrical charge difference, also known as the Coulomb force, counterbalances the concentration gradient, creating a voltage across the membrane.
This results in a layer of positive charge on the outside and a negative charge on the inside of the membrane due to the unbalanced distribution of other ions, particularly Cl-. Ultimately, this voltage is what gives rise to the resting membrane potential, which is critical for the excitability of nerve and muscle cells. If other ion channels like the Na+/K+ transporter don't function to re-equilibrate ion gradients, the cell would have trouble returning to its resting potential after any changes in membrane voltage, such as during an action potential.