Karyotheca or nuclear membrane is absent in

Options

A. Nostoc
B. Rhizobium
C. Drosophila
D. Both (1)&(2)

Answer

To determine in which organism the karyotheca (nuclear membrane) is absent, we can analyze the options provided:

1. **Understanding Karyotheca**: Karyotheca, or nuclear membrane, is a membrane that encloses the nucleus in eukaryotic cells. It is a characteristic feature of eukaryotic cells, which contain membrane-bound organelles.

2. **Identifying Cell Types**: There are two main types of cells:
- **Eukaryotic Cells**: These cells have a defined nucleus and membrane-bound organelles, including the nuclear membrane.
- **Prokaryotic Cells**: These are simpler cells that do not have a defined nucleus or membrane-bound organelles.

3. **Analyzing the Options**:
- **Nostoc**: This is a type of cyanobacteria, which is a prokaryotic organism. Therefore, it does not have a nuclear membrane.
- **Rhizobium**: This is also a prokaryotic organism (nitrogen-fixing bacteria), and like Nostoc, it lacks a nuclear membrane.
- **Drosophila**: This is a eukaryotic organism (a type of fruit fly) and has a nuclear membrane.
- **4192**: This option is unclear, but if it refers to another prokaryotic organism, it would also lack a nuclear membrane.

4. **Conclusion**: The organisms in which the karyotheca or nuclear membrane is absent are Nostoc and Rhizobium, as both are prokaryotic organisms.

**Final Answer**: Karyotheca or nuclear membrane is absent in Nostoc and Rhizobium (both are prokaryotic organisms).

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