Cohesion transpiration pull theory operates in

Options

A. passive water absorption
B. active water absorption
C. conditions favouring guttation
D. conditions restricting transpiration

Answer

### Step-by-Step Solution:

1. **Understanding Cohesion**:
- Cohesion refers to the attraction between water molecules. This force allows water molecules to stick together, which is crucial for their movement in plants.

**Hint**: Remember that cohesion is the force that keeps water molecules together.

2. **Role of Xylem**:
- In plants, water is transported through specialized tissues called xylem. The xylem vessels have narrow lumens that facilitate the movement of water.

**Hint**: Think of xylem as the highway for water transport in plants.

3. **Adhesion vs. Cohesion**:
- While cohesion is the attraction between water molecules, adhesion refers to the attraction between water molecules and the walls of the xylem vessels. Both forces are important for water movement.

**Hint**: Adhesion helps water cling to the xylem walls, while cohesion helps water molecules stick together.

4. **Cohesion-Transpiration Pull Theory**:
- This theory, proposed by Dixon and Jolly, explains how water moves from the roots to the leaves. As water evaporates from the leaves (transpiration), it creates a negative pressure that pulls more water upward through the xylem. The cohesive forces between water molecules help maintain the continuous column of water.

**Hint**: Think of transpiration as a straw effect that pulls water up due to evaporation.

5. **Passive Water Absorption**:
- The process described by the cohesion-transpiration pull theory is passive, meaning it does not require energy from the plant. Water moves naturally due to the differences in pressure created by transpiration.

**Hint**: Passive means that the plant does not have to expend energy for this process.

### Final Answer:
The cohesion-transpiration pull theory operates in **passive water absorption** in plants.