* Passive transport is the movement of molecules across a membrane without requiring energy. This is driven by the concentration gradient.

* Diffusion is the specific movement of molecules from a region of higher concentration to a region of lower concentration.

Therefore, a molecule moving across a semipermeable membrane into a region of higher concentration is not possible through passive transport or diffusion. This process would require active transport, which uses energy to move molecules against their concentration gradient.

Here's why active transport is necessary in this situation:

* Concentration gradient: Molecules naturally move from areas of high concentration to areas of low concentration to reach equilibrium.

* Energy requirement: Moving a molecule against its concentration gradient requires energy input, usually from ATP.

Example: The sodium-potassium pump is a classic example of active transport. It moves sodium ions out of the cell and potassium ions into the cell, against their concentration gradients.