Final answer:
The sodium ion (Na+) is primarily responsible for the kinetic energy transfer in a cell, largely through its role in the action potential facilitated by the sodium-potassium pump.
Step-by-step explanation:
The ion responsible for the majority of kinetic energy transfer in a cell is the sodium ion (Na+). The sodium-potassium pump plays a pivotal role in cellular function by actively moving sodium and potassium ions across the cell membrane using energy supplied by ATP. Three sodium ions (Na+) are pumped out of the cell, while two potassium ions (K+) are pumped into the cell, against their concentration gradients. This process not only creates a difference in ion concentration, but also a small electrical charge known as the action potential, which is fundamental for many cellular processes, including nerve signal transmission. It is important to note that while potassium (K+) also has a significant role, it is the movement of sodium ions during the action potential that facilitates the majority of kinetic energy transfer.