Question

diffusion of a substance across the cell membrane may be influenced by all of the following except its charge of the substance. its lipid solubility. the presence of membrane channels for the substance. the availability of atp. its concentration gradient.

Explanation:

Diffusion (including simple and facilitated diffusion) is a passive transport process that does not require energy (ATP). The charge of a substance affects its ability to cross the non - polar lipid bilayer (e.g., charged molecules have difficulty in simple diffusion). Lipid solubility is crucial for simple diffusion (substances with high lipid solubility cross the membrane easily). Membrane channels are involved in facilitated diffusion for certain substances. The concentration gradient is the driving force for diffusion (substances move from high to low concentration). Since diffusion is passive, ATP availability does not influence it.

Answer:

the availability of ATP.