Consider the following statements:
I. Red algae are red because of the presence of the pigment phycoerythrin, this pigment of reflects red light and absorbs blue light.
II. Because blue light penetrates water to a greater depth than light of longer wavelengths, these pigments allow red algae to photosynthesize and live at somewhat greater depths than most other "algae".

Options

A. Both I and II are correct and Il explains
B. Both I and II are correct and ll does not explains
C. I is correct but II is incorrect
D. Both I and II are incorrect

Answer

To analyze the statements regarding red algae, let's break down the information step by step.

### Step-by-Step Solution:

1. **Understanding the Pigment**:
- Red algae are characterized by the presence of a pigment called phycoerythrin. This pigment is responsible for the red coloration of these algae.
- **Hint**: Identify the pigment responsible for the color of red algae.

2. **Light Absorption**:
- Phycoerythrin reflects red light and absorbs blue light. This means that red algae can utilize blue light for photosynthesis, which is crucial for their survival.
- **Hint**: Consider how the absorption and reflection of light affect photosynthesis in red algae.

3. **Light Penetration in Water**:
- Blue light penetrates water to a greater depth compared to longer wavelengths (like red light). This characteristic allows red algae to thrive in deeper waters where blue light is more available.
- **Hint**: Think about the implications of light penetration in aquatic environments for different types of algae.

4. **Photosynthesis at Greater Depths**:
- Due to the ability to absorb blue light, red algae can photosynthesize effectively at depths where other algae, which may rely on red light, cannot survive.
- **Hint**: Explore how the ability to photosynthesize at greater depths gives red algae a competitive advantage.

5. **Conclusion on Statements**:
- Both statements I and II are correct. Statement I explains the reason for the red color of red algae, while Statement II explains how this adaptation allows them to live at greater depths.
- **Hint**: Evaluate the correctness of each statement based on the information provided.

### Final Evaluation:
- **Statement I**: Correct - Red algae are red due to phycoerythrin, which reflects red light and absorbs blue light.
- **Statement II**: Correct - The absorption of blue light allows red algae to photosynthesize at greater depths.

Thus, both statements are true.

### Summary:
- The correct conclusion is that both statements I and II are accurate regarding red algae and their adaptations.