There exists a close associatin between the algae and the fungus within a lichen. The fungus

Options

A. Provides food for the alga
B. Provides protection, anchorage and absorption for the alga
C. Fixes the atomospheric nitrogen for the alga
D. releases oxygen for the alga

Answer

### Step-by-Step Solution:

1. **Understanding Lichens**: Lichens are a symbiotic association between two organisms: a fungus and an alga. The alga is often a green alga or a blue-green alga (cyanobacteria).

2. **Identifying the Partners**: In this symbiotic relationship, the fungal partner is called the **mycobiont**, while the algal partner is referred to as the **phycobiont**.

3. **Role of the Fungus**: The fungus provides several essential functions for the alga:
- **Protection**: The fungal structure protects the algal cells from environmental stressors.
- **Anchorage**: The fungus anchors the alga to a substrate, ensuring stability.
- **Absorption**: The fungus absorbs water and minerals from the environment, which are then made available to the alga.

4. **Role of the Alga**: The alga, through photosynthesis, produces food (glucose) which is utilized by the fungus. Therefore, the alga provides food for the fungus, not the other way around.

5. **Evaluating the Options**:
- "Provides food for the algae" - Incorrect, as the alga provides food for the fungus.
- "Provides protection, anchorage, and absorption for the algae" - Correct, as these are the key roles of the fungus in the lichen.
- "Fixes atmospheric nitrogen" - Incorrect, as this is not a primary function of the fungus in lichen.
- "Releases oxygen for the algae" - Incorrect, as the alga itself produces oxygen through photosynthesis.

6. **Conclusion**: The correct answer is that the fungus provides protection, anchorage, and absorption for the algae.