Mannitol (sugar alcohol) is the stored food in

Options

A. Fucus
B. Gracillaria
C. Chara
D. Porphyra

Answer

To answer the question regarding where mannitol (a sugar alcohol) is stored as food, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organisms**: The question provides several options: Fucus, Gracilaria, Cara, and Porphyra. We need to analyze each organism to determine which one stores mannitol.

2. **Analyze Fucus**: Fucus is a brown algae that belongs to the group Pheophyceae. It is known to store food in the form of laminarin, mannitol, and oil. This indicates that mannitol is indeed one of the stored food substances in Fucus.

3. **Analyze Gracilaria**: Gracilaria is a red algae belonging to the Rhodophyceae group. The stored food in Gracilaria is in the form of Floridian starch and polysulphate esters. Therefore, mannitol is not stored here.

4. **Analyze Cara**: Cara is a green algae from the Chlorophyceae group. The stored food in Cara is in the form of starch and oil, which means it does not store mannitol.

5. **Analyze Porphyra**: Porphyra is also a red algae that belongs to the Rhodophyceae group. Similar to Gracilaria, it stores food in the form of Floridian starch and polysulphate esters, indicating that mannitol is not stored here either.

6. **Conclusion**: After analyzing all the options, we can conclude that mannitol is the stored food in Fucus, which is the only organism among the options that stores mannitol.

### Final Answer:
Mannitol (sugar alcohol) is the stored food in **Fucus**.