Question

Osmosis is the movement of
A. Solute particles from lower to higher concentration
B. Solute particles from higher to lower concentration
C. Solvent particles from lower to higher concentration
D. Solvent particles from higher to lower concentration

Answer 1

Hint: Diffusion and osmosis take place through a semipermeable membrane i.e., which transports only selected particles through them. Diffusion and osmosis are driven by concentration gradient and not by energy gradient or by utilizing ATP. They can be defined in terms of either solute or solvent.

Complete answer:
Option A solute particles from lower to higher concentration: Osmosis is always based on concentration of solvent. Therefore, defining osmosis in terms of solute cannot be considered correct.
So, A is not the correct option.
Option B solute particles from higher to lower concentration: Osmosis cannot be defined in terms of solutes. When solute moves from higher to lower concentration, it is considered as diffusion. In diffusion solute tends to move from higher to lower concentration.
So, B is not the correct option.
Option C solvent particles from lower to higher concentration: Osmosis is movement of solvent from higher to lower solvent concentration and hence this is incorrect when stated that solvent from lower to higher concentration.
So, C is not the correct option
Option D solvent particles from higher to lower concentration: Osmosis is the movement of solvent from higher to lower concentration.
So, D is the correct option.

So, option D is the correct answer

Note:
Osmosis is defined based on solvent concentration as the movement of water/solvent from higher solvent to lower solvent concentration. Which in turn means that where solute is less water is more and vice versa. Hence water moves where solutes are less to where solutes are more.