Root hairs absorb water from soil when

Options

A. Osmotic concentration is same in the two systems
B. Solute concentration is higher in soil solution
C. Solute concentration is higher in soul solution
D. Absorption is active

Answer

### Step-by-Step Text Solution:

1. **Understanding Root Hairs**: Root hairs are specialized structures on the roots of plants that play a crucial role in the absorption of water and nutrients from the soil.

2. **Role of Osmotic Pressure**: The absorption of water by root hairs is primarily driven by osmotic pressure. Osmosis is the movement of water from an area of lower solute concentration to an area of higher solute concentration through a semi-permeable membrane.

3. **Condition for Water Absorption**: Root hairs absorb water from the soil when the osmotic pressure between the root hair cells and the surrounding soil solution is equal. This means that the concentration of solutes in the root hair cells and the soil solution must be similar.

4. **Analyzing the Options**:
- **Option 1**: Osmotic concentration is the same in both systems. This is correct because equal osmotic pressure allows for the passive movement of water into the root hairs.
- **Option 2**: Solute concentration is higher in soil solution. This is incorrect because if the solute concentration is higher in the soil, water would not move into the root hairs; instead, it would require active transport.
- **Option 3**: Solution concentration is higher in soil solution. This is also incorrect for the same reason as above.
- **Option 4**: Absorption is active. This is incorrect because the absorption of water by root hairs is a passive process, relying on osmotic pressure rather than energy expenditure.

5. **Conclusion**: The correct condition for root hairs to absorb water from the soil is when the osmotic concentration is the same in both the root hairs and the soil solution.

### Final Answer:
Root hairs absorb water from soil when the osmotic concentration is the same in both systems.

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