Phloem loading and unloading process are respectively

Options

A. Active , Passive
B. Passive , Active
C. Active , Active
D. Passive , Passive

Answer

To answer the question regarding the processes of phloem loading and unloading, we can break it down step by step:

### Step-by-Step Solution:

1. **Understanding Phloem Function**:
- Phloem is responsible for the transport of organic nutrients, particularly sucrose, throughout the plant. It consists of sieve tubes that facilitate this transport.

2. **Phloem Loading**:
- Phloem loading refers to the process of transferring soluble sugars (like sucrose) from mesophyll cells (where photosynthesis occurs) into the sieve tube elements of the phloem.
- This process requires energy because it involves the active transport of sugars against a concentration gradient.

3. **Phloem Unloading**:
- Phloem unloading is the process of transferring the sugars from the sieve tube elements to the surrounding tissues where they are utilized (e.g., for growth or storage).
- Similar to loading, unloading also requires energy, as it often involves moving sugars from areas of higher concentration in the sieve tubes to lower concentrations in the surrounding tissues.

4. **Conclusion**:
- Since both phloem loading and unloading require energy, they are classified as active processes. Therefore, the correct answer to the question is that phloem loading and unloading are respectively **active-active** processes.

### Final Answer:
Phloem loading and unloading processes are respectively **active-active**.

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