Which is not true regarding active water absorption ?

Options

A. Require energy
B. Occurs only when transpiration is slow
C. Living cells are essential
D. Force develops is shoot

Answer

To determine which statement is not true regarding active water absorption, let's analyze the characteristics of active water absorption step by step:

### Step-by-Step Solution:

1. **Definition of Active Water Absorption**:
- Active water absorption is the process by which plants absorb water from the soil against the osmotic gradient. This process requires energy, which is derived from metabolic activities within the plant cells.

2. **Energy Requirement**:
- Active water absorption requires energy. This energy is typically obtained from the process of respiration occurring in the living cells of the roots.

3. **Conditions for Active Water Absorption**:
- Active water absorption occurs primarily when transpiration rates are low. Under normal conditions, transpiration (the loss of water vapor from plant surfaces) creates a negative pressure that helps draw water up from the roots. However, when transpiration is slow, plants may rely more on active absorption.

4. **Role of Living Cells**:
- Living cells are essential for active water absorption. The metabolic processes in these cells are crucial for the absorption of water against the osmotic gradient.

5. **Passive vs. Active Absorption**:
- Passive absorption occurs due to the physical forces created by transpiration, primarily in the shoots of the plant. In contrast, active absorption is a process that takes place in the roots and does not rely on the transpiration pull.

6. **Identifying the False Statement**:
- The statement that is not true regarding active water absorption is: "The force of passive absorption develops in shoots." This statement is misleading because it pertains to passive absorption, not active absorption.

### Conclusion:
The statement that is not true regarding active water absorption is that "the force develops in shoots." Active water absorption occurs in the roots and requires energy, while passive absorption is influenced by transpiration and occurs in the shoots.