The document explains the process of diffusion across a membrane, highlighting that permeable solutes move from higher to lower concentration until equilibrium is reached, with passive transport requiring no energy. It contrasts simple diffusion, which pertains to solutes, with osmosis, which specifically describes water movement across selectively permeable membranes. Both processes occur until concentrations equalize on both sides of the membrane.

1. If a concentration gradient has been established across a membrane, the permeable solute will
diffuse across the membrane from the side with the higher concentration to the side with the
lower concentration so slowly that there will be no movement of these molecules, even though
the membrane is permeable to them. from the side with the lower concentration to the side with
the higher concentration. In both directions, but with no "net" movement In any particular
direction.
Solution
Answer: (a)
If a concentration gradient has been established across a membrane, the permeable solute will
diffuse across the membrane from the side with the higher concentration to the side with the
lower concentration.
Passive transport is the movement of solutes and molecular substances across cell membranes
without need of energy input. It is the net movement of solutes across the cell membrane along
the concentration gradient and continues until an equilibrium has been reached.
Simple diffusion and osmosis are in someway similar. Simple diffusion is the passive movement
of solute from a high concentration to a lower concentration until the concentration of the solute
is uniform. Osmosis describes the movement of water (not the solute) across a selectively
permeable membrane until there is an equal concentration of water and solute on both sides of
the membrane.