Answer:
From high to low.
Explanation:
When we say "high to low" and "low to high", when talking about cells, diffusion, passive transport, etc. we are referring to the concentration of the solute in both sides of the biological membrane.
In simple diffusion, the molecules travel from a higher concentration to a lower concentration, in order to create a uniform environment.
The opposite of diffusion is osmosis, meaning that in osmosis the opposite happens; in this case, molecules are "attracted" to the higher concentration side of a biological membrane, and travel to it.
Hope it helped,
BiologiaMagister
