Nuclear membrane is absent in

Options

A. Penicillium
B. Agaricus
C. Volvox
D. Nostoc

Answer

To determine where the nuclear membrane is absent, we need to understand the differences between prokaryotic and eukaryotic cells.

### Step-by-Step Solution:

1. **Understand Cell Types**:
- Cells are classified into two main types: prokaryotic and eukaryotic.
- Prokaryotic cells are simpler and do not have a well-defined nucleus, while eukaryotic cells have a well-defined nucleus enclosed by a nuclear membrane.

2. **Identify Prokaryotes**:
- Prokaryotes include organisms from the kingdom Monera, such as bacteria and cyanobacteria.
- These organisms have a poorly developed nucleus, meaning they lack a nuclear membrane.

3. **Evaluate the Options**:
- The question provides several options to choose from. We need to identify which of these options is a prokaryote.
- **Option 1: Penicillin** - This is a type of fungi, which is a eukaryote and has a nuclear membrane.
- **Option 2: Agaricus** - This is a mushroom, also a eukaryote, and has a nuclear membrane.
- **Option 3: Volvox** - This is a green algae, which is a eukaryote and has a nuclear membrane.
- **Option 4: Nostoc** - This is a cyanobacterium, which is a prokaryote and lacks a nuclear membrane.

4. **Conclusion**:
- Since Nostoc is the only organism listed that is a prokaryote and lacks a nuclear membrane, it is the correct answer.

### Final Answer:
The nuclear membrane is absent in **Nostoc**.