Organic substances such as sugars are translocated in the phloem. This phenomenon was shown by

Options

A. Girdling experiment
B. Root pressure theory
C. Experiment by Dixon and Jolly
D. munch hypothesis

Answer

To solve the question regarding which experiment demonstrated that organic substances such as sugars are translocated in the phloem, we can follow these steps:

### Step 1: Understand the Role of Phloem
Phloem is the vascular tissue in plants responsible for the transport of organic compounds, particularly sugars produced during photosynthesis, from the leaves to other parts of the plant.

**Hint:** Recall that phloem is primarily involved in the transport of food, while xylem is involved in the transport of water.

### Step 2: Identify the Experiments Listed
The question provides four options:
1. Girdling Experiment
2. Root Pressure Theory
3. Experiment by Dixon and Jolly
4. Munch Hypothesis

**Hint:** Consider the focus of each option: which one specifically addresses the transport of sugars?

### Step 3: Analyze the Girdling Experiment
The Girdling Experiment involves removing a ring of bark from a tree, which includes the phloem layer. After this procedure, the area above the girdle swells due to the accumulation of sugars that cannot be transported down to the roots, indicating that phloem is responsible for the translocation of food.

**Hint:** Think about what happens when you block a pathway in a system; what accumulates, and what does that indicate about the role of that pathway?

### Step 4: Evaluate Other Options
- **Root Pressure Theory**: This theory explains the movement of water and does not focus on sugar transport.
- **Experiment by Dixon and Jolly**: This experiment is related to water transport, not sugar translocation.
- **Munch Hypothesis**: While it explains the pressure flow mechanism of sugar transport, it is not an experimental demonstration like the Girdling Experiment.

**Hint:** Focus on the nature of the evidence provided by each experiment—does it show a direct impact on sugar transport?

### Step 5: Conclude the Correct Answer
Based on the analysis, the Girdling Experiment is the one that clearly demonstrated that organic substances such as sugars are translocated in the phloem. The swelling above the girdled area indicates that the phloem is essential for transporting sugars down to the roots.

**Final Answer:** The phenomenon of organic substances such as sugars being translocated in the phloem was shown by the **Girdling Experiment**.