Zoochlorellae and zooxanthallae present in Hydra are

Options

A. Symbionts in nutritive cells
B. Symbionts in the gut
C. Symbionts in cnidoblasts
D. Organisms that provide hypnotoxin

Answer

To answer the question regarding the presence of zoochlorellae and zooxanthellae in Hydra, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organisms**:
- Zoochlorellae are green algae, while zooxanthellae are brown algae. Both are types of algae that can live in symbiotic relationships with other organisms.

2. **Understand the Symbiotic Relationship**:
- In the context of Hydra, zoochlorellae and zooxanthellae exist in a symbiotic association. This means that both the algae and Hydra benefit from this relationship.

3. **Location of the Algae in Hydra**:
- These algae are specifically found in the nutritive cells of Hydra. The nutritive cells are responsible for digestion and nutrient absorption.

4. **Function of the Algae**:
- The presence of these algae helps Hydra to survive in environments where nutrients may be scarce. The algae perform photosynthesis, providing energy and nutrients to Hydra.

5. **Evaluate the Options**:
- Given the options:
- Option 1: Symbiont in nutritive cell (Correct)
- Option 2: Symbiont in the gut (Incorrect)
- Option 3: Symbionts in the neuroblast (Incorrect)
- Option 4: Organism that provides hypnotoxin (Incorrect)
- The correct answer is Option 1, as the algae are indeed symbionts located in the nutritive cells of Hydra.

### Final Answer:
Zoochlorellae and zooxanthellae present in Hydra are **symbionts in the nutritive cells**.

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