Question

A semipermeable membrane allows the diffusion of

• A. solutes
• B. Solvent
• C. Both solvent and solutes
• D. none of the above

Answer 1

The correct option is C

Explanation of the correct answer:

1. A semipermeable membrane allows only solvent molecules to pass through while leaving behind solute molecules.
2. Such type of diffusion of water through a semi-permeable membrane is called osmosis.
3. Semi-permeable means that the membrane will allow small molecules and ions to pass through it but acts as a barrier to larger molecules or dissolved substances.
4. It is important for the uptake of substances needed by cells, and also the removal of waste products produced by the cells.

5. Solvent molecules like water molecules are generally very small compared to the size of the solute particle.

Explanation of the incorrect answers:

Option A:

1. Semi-permeable membranes allow the movement of the solvent particles.

2. Hence, this option is invalid.

Option B:

1. The size of the solute particles is very large to pass through the membrane.
2. Hence, solute particles do not diffuse across the semi-permeable membrane.

Option D:

1. The size of the solute particles is very large to pass through the membrane.

2. Hence, a semipermeable membrane allows the diffusion of only solvent molecules.

Final answer: A semipermeable membrane allows the diffusion of solvent.