No net diffusion of water takes place when

Options

A. A dry seed is placed in a dilute solution
B. A plant is exposed to gentle breeze
C. A cell is placed in an isotonic solution
D. A deplasmolysed cell is placed in hypertonic solution

Answer

To answer the question "No net diffusion of water takes place when," we need to understand the concept of net diffusion in the context of plant cells and solutions. Here’s a step-by-step solution:

### Step-by-Step Solution:

1. **Understanding Net Diffusion**:
- Net diffusion refers to the overall movement of water molecules across a semipermeable membrane. It occurs when there is a concentration gradient, meaning water moves from an area of higher concentration to an area of lower concentration until equilibrium is reached.

**Hint**: Think about how molecules move from crowded areas to less crowded areas.

2. **Identifying Conditions for No Net Diffusion**:
- No net diffusion occurs when the concentration of solutes (and thus water) is equal on both sides of the membrane. This condition is known as isotonic.

**Hint**: Consider what happens when two solutions have the same concentration of solutes.

3. **Analyzing the Options**:
- **Option 1**: A dry seed is placed in a dilute solution.
- In this case, water will move into the dry seed, leading to net diffusion. **(Incorrect)**

**Hint**: Remember that water moves towards areas of lower water potential.

- **Option 2**: A plant is exposed to a gentle breeze.
- While this may affect transpiration rates, it does not create a condition of no net diffusion. **(Incorrect)**

**Hint**: Think about how environmental factors can influence water movement.

- **Option 3**: A cell is placed in an isotonic solution.
- Here, the concentration of solutes is equal inside and outside the cell, resulting in equal rates of water entering and leaving the cell. Therefore, there is no net diffusion. **(Correct)**

**Hint**: Visualize a balance where incoming and outgoing water molecules are equal.

- **Option 4**: A de-plasmalized cell is placed in a hypotonic solution.
- In a hypotonic solution, water will move into the cell, causing it to swell, which means there is net diffusion occurring. **(Incorrect)**

**Hint**: Consider what happens to a cell when placed in a solution with lower solute concentration.

4. **Conclusion**:
- The correct answer is that no net diffusion of water takes place when a cell is placed in an isotonic solution.

### Final Answer:
No net diffusion of water takes place when a cell is placed in an isotonic solution.