Final answer:
When a concentration gradient is established for K+ ions, they tend to move from the compartment with higher concentration to the one with lower concentration. This movement of K+ ions contributes to a change in the membrane potential and is important for cellular processes.
Step-by-step explanation:
In this scenario, compartment A is filled with 100 mM KCl, which creates a high concentration gradient for K+ ions. On the other hand, compartment B is filled with 10 mM KCl and 90 mM NaCl, resulting in a lower concentration gradient for K+ ions. As a result, K+ ions will tend to move from compartment A to compartment B, as they move down their concentration gradient. This movement of K+ ions will continue until equilibrium is reached.
It's important to note that K+ ions have a positive charge, and their movement will contribute to a change in the membrane potential of the cells or compartments involved. This change in membrane potential is important for various cellular processes, such as nerve transmission and muscle contraction.