Question

which motion of particles across a membrane requires energy? from high concentration to low concentration from low concentration to high concentration with no concentration gradient through dynamic equilibrium

Explanation:

Diffusion is the movement of particles from high - concentration to low - concentration without energy input. Active transport is the movement of particles from low - concentration to high - concentration and requires energy. Movement with no concentration gradient doesn't require energy for the movement itself related to concentration change. Movement through dynamic equilibrium also doesn't require energy for the movement across the membrane due to the balanced state.

Answer:

from low concentration to high concentration