Which is correct w.r.t. lichens ?

Options

A. Mycobiont is autotrophic component
B. Phycobiont is heterotrophic component
C. They are good pollution indicators
D. They do not grow non-pollution indicators

Answer

To determine which statements are correct with respect to lichens, we need to analyze the components and characteristics of lichens.

### Step-by-Step Solution:

1. **Understanding Lichens**:
- Lichens are a symbiotic association between fungi (mycobiont) and algae or cyanobacteria (phycobiont).
- The fungal component (mycobiont) provides structure and protection, while the algal component (phycobiont) is responsible for photosynthesis.

2. **Identifying Components**:
- The **mycobiont** (fungal partner) is **heterotrophic**, meaning it obtains nutrients from other organic sources.
- The **phycobiont** (algal partner) is **autotrophic**, meaning it can produce its own food through photosynthesis.

3. **Evaluating Pollution Sensitivity**:
- Lichens are known to be sensitive to air pollution, particularly sulfur dioxide. They are often used as bioindicators of air quality.
- They thrive in clean environments and are not found in areas with high pollution levels.

4. **Growth Rate**:
- The growth rate of lichens is very slow, often less than a millimeter per year. This slow growth can be used to estimate the age of exposed rocks.

5. **Analyzing the Statements**:
- **Statement 1**: "Mycobiont is autotrophic component" - This is **incorrect**; mycobiont is heterotrophic.
- **Statement 2**: "Phycobiont is a heterotrophic component" - This is **incorrect**; phycobiont is autotrophic.
- **Statement 3**: "They are good pollution indicators" - This is **correct**; lichens are sensitive to pollution and serve as indicators of air quality.
- **Statement 4**: "They do not grow in non-polluted environments" - This is **incorrect**; lichens grow in non-polluted environments.

### Conclusion:
The only correct statement with respect to lichens is that they are good pollution indicators.