Lichens are composite organisms consisting of an alga and ______

Options

A. Mosses
B. Fungus
C. Protozoa
D. Bacterium

Answer

**Step-by-Step Solution:**

1. **Understanding Lichens**: Lichens are unique organisms that are formed from the symbiotic relationship between two different types of organisms.

2. **Identifying the Components**: The two components of lichens are an alga and another organism. In this case, we need to identify what the second organism is.

3. **Analyzing the Options**: The options provided are:
- Mosses
- Fungus
- Protozoa
- Bacteria

4. **Recognizing the Role of Alga**: The alga in lichens is responsible for photosynthesis. It contains chloroplasts, which allow it to convert sunlight into energy, producing food for both itself and the fungus.

5. **Recognizing the Role of Fungus**: The fungus in lichens plays a crucial role in absorbing water and nutrients from the environment. It provides a protective structure for the alga and helps retain moisture.

6. **Conclusion**: Since lichens consist of an alga and a fungus, the correct answer to the question is "fungus."

**Final Answer**: Lichens are composite organisms consisting of an alga and **fungus**.

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