Which of these statement/s about lichens is/are ture?
I. Lichens are mutually beneficial symbotic associations.
II. They grow extensively in area with high pollution, hence called as pollution indicators.
III. The phycobiont member, algae, is an autotroph and the mycobiont member, fungi, is a heterotroph.
IV. Fungi help the algae harvest sunlight for photosynthesis.

Options

A. II and III
B. I and III
C. I, II and III
D. III and IV

Answer

To determine which statements about lichens are true, let's analyze each statement one by one.

### Step 1: Analyze Statement I
**Statement I:** Lichens are mutually beneficial symbiotic associations.
- **Explanation:** Lichens are indeed a symbiotic association between fungi (mycobiont) and algae (phycobiont). In this relationship, both organisms benefit: the fungi provide structure and protection, while the algae perform photosynthesis and provide nutrients.
- **Conclusion:** This statement is **true**.

### Step 2: Analyze Statement II
**Statement II:** They grow extensively in areas with high pollution, hence called pollution indicators.
- **Explanation:** Lichens are sensitive to air quality, particularly sulfur dioxide and other pollutants. They are often found in clean environments and are used as bioindicators of air pollution. High pollution levels can inhibit their growth.
- **Conclusion:** This statement is **false**.

### Step 3: Analyze Statement III
**Statement III:** The phycobiont member, algae, is an autotroph and the mycobiont member, fungi, is a heterotroph.
- **Explanation:** The algae (phycobiont) are autotrophs because they can produce their own food through photosynthesis. The fungi (mycobiont) are heterotrophs as they rely on the algae for organic carbon.
- **Conclusion:** This statement is **true**.

### Step 4: Analyze Statement IV
**Statement IV:** Fungi help the algae harvest sunlight for photosynthesis.
- **Explanation:** This statement is misleading. While fungi provide a structure that can help protect the algae, they do not assist in harvesting sunlight. The algae themselves carry out photosynthesis independently.
- **Conclusion:** This statement is **false**.

### Final Conclusion
Based on the analysis:
- **True Statements:** I and III
- **False Statements:** II and IV

Thus, the correct answer is that statements I and III are true.