A protistan which is commonly called plant-animals is

Options

A. Navicula
B. Noctiluca
C. Vorticella
D. Euglena.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a protistan that is commonly referred to as "plant-animal." This indicates that the organism in question exhibits characteristics of both plants and animals.

2. **Identifying Characteristics of Protists**: Protists are a diverse group of eukaryotic microorganisms. Some protists can perform photosynthesis like plants (autotrophic), while others can consume organic material like animals (heterotrophic).

3. **Analyzing the Options**: The options given are:
- Navicula
- Nocticula
- Vorticella
- Euglena

4. **Evaluating Each Option**:
- **Navicula**: This is a diatom with a silica cell wall and is primarily autotrophic.
- **Nocticula**: This is a heterotrophic organism that is bioluminescent and found in oceans.
- **Vorticella**: This is a heterotrophic organism that preys on bacteria using cilia.
- **Euglena**: This organism is known for its mixotrophic nature, meaning it can photosynthesize when light is available (like a plant) and can also absorb nutrients from the environment when light is not available (like an animal).

5. **Conclusion**: Based on the characteristics of the organisms listed, the protistan that is commonly called "plant-animal" is **Euglena**. This is due to its ability to perform both photosynthesis and heterotrophic feeding.

**Final Answer**: Euglena

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