Question

what direction do substances move during diffusion?
from no concentration to full concentration
from low to high concentration
from high to low concentration

Explanation:

Diffusion is the passive movement of substances (like molecules or ions) across a membrane or in a solution. The fundamental principle of diffusion is that substances move down their concentration gradient. A concentration gradient exists when there is a difference in the concentration of a substance between two regions. In diffusion, particles naturally move from an area where their concentration is high (more particles per unit volume) to an area where their concentration is low (fewer particles per unit volume). This movement occurs because the random motion of particles (Brownian motion) leads to a net movement towards areas of lower concentration to achieve equilibrium (a state where the concentration is uniform throughout the system).

Let's analyze the given options:

• "from no concentration to full concentration": This is not a valid description of diffusion. There's no such thing as "no concentration" in a meaningful context for diffusion, and diffusion doesn't aim to go from "no" to "full" concentration. It's about equalizing existing concentrations.
• "from low to high concentration": Movement from low to high concentration is actually active transport, which requires energy input (like ATP) to move substances against their concentration gradient. Diffusion is passive and does not require energy, so it doesn't move substances from low to high concentration.
• "from high to low concentration": This matches the definition of diffusion. Substances move from an area of higher concentration to an area of lower concentration to spread out and reach equilibrium.

Answer:

from high to low concentration