Longitudinal binary fission is present in

Options

A. Euglena
B. Paramecium
C. Dinoflagellate
D. Diatom

Answer

To determine which organism undergoes longitudinal binary fission, we can analyze the options provided: Euglena, Paramecium, Dinoflagellates, and Diatoms.

### Step-by-Step Solution:

1. **Understanding Longitudinal Binary Fission**:
- Longitudinal binary fission is a type of asexual reproduction where an organism divides into two equal halves along its length. This process results in two daughter cells that are genetically identical to the parent cell.

2. **Analyzing the Options**:
- **Euglena**: This is a unicellular organism that has a flagellum and can perform photosynthesis. Euglena reproduces through longitudinal binary fission.
- **Paramecium**: This organism reproduces mainly through a process called conjugation, although it can also reproduce asexually through binary fission, but not specifically longitudinally.
- **Dinoflagellates**: These are a group of protists that can reproduce asexually, but they typically do not do so through longitudinal binary fission.
- **Diatoms**: These are a type of algae that reproduce asexually through a process called cell division, but not specifically through longitudinal binary fission.

3. **Conclusion**:
- Based on the characteristics of each organism, the one that undergoes longitudinal binary fission is **Euglena**.

### Final Answer:
**Euglena** is the organism that undergoes longitudinal binary fission.

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