Question

In most resting cells, the concentration of sodium ions is higher outside of cells compared with the intracellular fluid. When cells are stimulated, sodium ion channels open, and sodium diffuses from the outside of the cell to the inside of the cell. Sodium ion concentrations in a resting cell are an example of ___________, and sodium ion movement in a stimulated cell is an example of ___________.

the energy of motion; stored energy

potential energy; kinetic energy

kinetic energy; potential energy

chemical work; energy stored in chemical bonds

Answer 1

Sodium ion concentrations in a resting cell are an example of Potential Energy, and sodium ion movement in a stimulated cell is an example of Kinetic Energy.

Explanation: In resting cell there is a voltage difference between extracellular fluid and intracellular fluid(E.g -70mV for nerve cell), So this voltage is required for maintaining the resting state(no action potential is not generated in this state). In this condition cell stored energy as a potential difference. This potential energy is used for the stored or inactive state of the particular cell.

But, whenever a cell is stimulated that potential energy converted to kinetic energy(by opening sodium channel) and for this reason energy propagated through the cell to target region by action potential. So the inward sodium ion movement in a stimulated cell is an example of kinetic energy. This kinetic energy is used for the action of that particular cell.

Wrong Option: First option is incorrect because, in resting state there is no flow of sodium so this state can't be an example of the energy of motion, and in excited cell there is a flow of sodium ion so this state also can't be a example of stored energy.

Last option is also incorrect because in excited state of a cell there is no energy stored in chemical bonds, in this state stored energy transfer into action, so last option is also incorrect.