Class IX Biology - Chapter: Cell - Topic: Osmosis Numerical Problems

Problem 1: Osmosis in Plant Cells

A plant cell with an internal solute concentration equivalent to 0.3M sucrose is placed in a solution. After some time, the cell becomes turgid. What can you infer about the external solution's concentration relative to the cell's internal concentration?

Solution:

When a plant cell becomes turgid, it means water has moved into the cell by osmosis, causing the cell membrane to press against the cell wall. This occurs when the external solution has a lower solute concentration (hypotonic) than the cell's internal environment. Therefore, the external solution's concentration must be less than 0.3M sucrose.

Problem 2: Water Movement Across a Semi-permeable Membrane

Two solutions, A and B, are separated by a semi-permeable membrane. Solution A has a 5% glucose concentration, and Solution B has a 10% glucose concentration. In which direction will there be a net movement of water?

Solution:

Osmosis is the net movement of water from a region of higher water potential (lower solute concentration) to a region of lower water potential (higher solute concentration) across a semi-permeable membrane.

• Solution A: 5% glucose (higher water potential, lower solute concentration)
• Solution B: 10% glucose (lower water potential, higher solute concentration)

Therefore, there will be a net movement of water from Solution A to Solution B.