Concept:Active transport is the movement of substances across a cell membrane against their concentration gradient, requiring cellular energy (ATP) usually derived from respiration.
Explanation:In active transport, molecules move from a region of lower concentration to a region of higher concentration.
This movement is against the diffusion gradient, so it is not spontaneous.
Energy is needed to overcome the gradient; this energy comes from the breakdown of ATP during cellular respiration.
Passive transport (like facilitated diffusion) moves substances along the gradient without energy.
Photosynthesis provides energy in plants, but the universal immediate energy source for active transport is ATP from respiration.
Thus, the correct description is: movement against the diffusion gradient using energy from respiration.
Answer:Option A: It is the movement of a substance against a diffusion gradient with the use of energy from respiration.