Final answer:
In most animal cells, potassium ions (K+) can move through "leak" channels, which are responsible for maintaining the cell's resting membrane potential by allowing these ions to follow their concentration gradient in and out of the cell.
Step-by-step explanation:
In most animal cells, potassium ions (K+) can move through "leak" channels. These leak channels are specialized ion channels that are always open, allowing ions to move in and out of the cell following their concentration gradients. While other ions like sodium (Na+), calcium (Ca2+), and chloride (Cl-) are also present in cells, it is specifically potassium ions that primarily move through these leak channels.
The sodium-potassium pump actively maintains the concentration gradients of Na+ and K+ by pumping sodium out of the cell and potassium into the cell, using ATP for energy. Concurrently, K+ leak channels, which are open around 90% of the time, allow K+ ions to move out of the cell. This movement through leak channels contributes to the cell's resting membrane potential and is an essential process for normal cell function.