Binary fission is absent in

Options

A. Monocystis/Plasmodium
B. Euglena
C. Paramecium
D. Amoeba.

Answer

To determine which organism does not reproduce by binary fission, we will analyze the given options one by one:

1. **Amoeba**:
- Amoeba reproduces asexually through a process known as binary fission. Specifically, it undergoes irregular binary fission.
- Therefore, binary fission is present in Amoeba.

2. **Paramecium**:
- Paramecium also reproduces asexually by binary fission, which is known as transverse binary fission.
- Hence, binary fission is present in Paramecium.

3. **Euglena**:
- Euglena reproduces asexually through binary fission as well, specifically through longitudinal binary fission.
- Thus, binary fission is present in Euglena.

4. **Plasmodium**:
- Plasmodium primarily reproduces sexually through a process called isogamy. When it reproduces asexually, it does so through a process known as schizogony, which is a form of multiple fission.
- Therefore, binary fission is absent in Plasmodium.

Based on the analysis, the organism in which binary fission is absent is **Plasmodium**.

### Final Answer:
Binary fission is absent in **Plasmodium**.