What is kinetic energy in terms of molecular motion?

Kinetic energy, in the context of molecular motion, refers to the energy possessed by molecules due to their movement. This energy is directly related to the speed and mass of the molecules; the faster they move, the more kinetic energy they have. Molecular motion can occur in various forms, such as translational (movement through space), rotational (spinning around an axis), and vibrational (atoms within a molecule oscillating).

Understanding kinetic energy as the energy of motion helps explain various biological processes, including diffusion, reaction rates, and temperature. For instance, at higher temperatures, molecules move more rapidly, leading to increased kinetic energy, which can facilitate faster reactions.

The other choices do not accurately capture the definition of kinetic energy in this context. Energy stored in chemical bonds pertains to potential energy, while energy of a system at rest does not involve motion at all. Energy lost due to friction refers to energy conversion into heat, which is also not related to the general concept of kinetic energy.