Final answer:
Ions move in response to electrochemical gradients, which are combinations of diffusional and electrical gradients. Sodium ions (Na+) move into cells, influenced by these gradients, while potassium ions (K+) have a more complex relationship due to opposing forces of their gradients.
Step-by-step explanation:
The behavior of ions can be related to both diffusional and electrical gradients in several ways. An example is sodium ions (Na+), which tend to move into cells due to a high concentration outside of the cell and a negative charge inside the cell, creating a concentration gradient and an electrical gradient that together form an electrochemical gradient. This combined gradient influences ion movement across the cell membrane. In contrast, potassium ions (K+) have a tendency to leave the cell because their concentration is higher inside the cell than outside, but they are also attracted inside by the negative electrical charge within the cell. Therefore, the behavior of ions in relation to gradients can be complex.
Ions move in response to these gradients, generally moving down their concentration gradient (diffusional) and toward the opposite electrical charge (electrical). However, in active transport, ions can move against their concentration gradient with the use of energy from the cell.