Pressure developed in seive elements during transports of sucrose is

Options

A. Positive
B. Negative
C. Zero
D. None

Answer

To answer the question regarding the pressure developed in sieve elements during the transport of sucrose, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Sieve Elements**: Sieve elements are specialized cells in the phloem tissue of plants responsible for the transport of organic nutrients, primarily sucrose.

2. **Role of Phloem**: The phloem transports food materials (like sucrose) from the leaves (where photosynthesis occurs) to other parts of the plant (roots, stems, and fruits). This process is known as translocation.

3. **Pressure Development**: During the transport of sucrose through sieve elements, a pressure is developed due to the osmotic movement of water into the phloem. This pressure is essential for pushing the sap (which contains sucrose) through the sieve tubes.

4. **Hydrostatic Pressure**: The pressure generated in the sieve elements is referred to as hydrostatic pressure. In the context of phloem transport, this pressure is typically positive.

5. **Comparison with Xylem**: In contrast to phloem, xylem transports water and minerals from the roots to the leaves. The pressure in xylem is negative due to the tension created by water evaporation from the leaves (transpiration).

6. **Conclusion**: Since the flow of sucrose in the phloem is driven by positive hydrostatic pressure, the answer to the question is that the pressure developed in sieve elements during the transport of sucrose is **positive**.

### Final Answer:
The pressure developed in sieve elements during the transport of sucrose is **positive**.

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