Coralloid roots of Cycas has

Options

A. Anabaena
B. Nostoc
C. Mycorrhizae
D. Rhizopus

Answer

To answer the question "Coralloid roots of Cycas has," we can follow these steps:

### Step-by-Step Solution:

1. **Understand Coralloid Roots**:
- Coralloid roots are specialized roots found in certain plants, including Cycas. They are characterized by their coral-like appearance and are involved in symbiotic relationships.

**Hint**: Look for the definition and characteristics of coralloid roots in plant biology.

2. **Identify the Function of Coralloid Roots**:
- These roots are primarily associated with nitrogen fixation, which is essential for the plant's nutrient uptake.

**Hint**: Consider the role of roots in nutrient acquisition and symbiotic relationships.

3. **Determine the Type of Symbiotic Bacteria**:
- The coralloid roots of Cycas specifically host a type of cyanobacteria known as Anabaena, which plays a crucial role in nitrogen fixation.

**Hint**: Research the types of bacteria associated with different plant roots, especially in relation to nitrogen fixation.

4. **Differentiate Between Other Bacteria**:
- Other options mentioned, such as Nostoc, Mycorrhiza, and Rhizopus, do not form symbiotic relationships with Cycas. Nostoc typically associates with angiosperms and non-vascular plants, while Mycorrhiza involves fungi, and Rhizopus is a saprophytic fungus.

**Hint**: Compare and contrast the different types of symbiotic relationships in plants to identify the correct association.

5. **Conclude the Answer**:
- Based on the information gathered, the correct answer is that the coralloid roots of Cycas have Anabaena.

**Hint**: Summarize your findings to arrive at the final answer clearly.

### Final Answer:
Coralloid roots of Cycas have **Anabaena**, a nitrogen-fixing cyanobacterium.