Nuclear membrane is absent in

Options

A. penicillium
B. agaricus
C. volvox
D. nostoc

Answer

To determine which organism lacks a nuclear membrane, we can analyze the options provided in the question. Here’s the step-by-step solution:

### Step 1: Understand the Structure of Cells
- Cells can be classified into two main types: prokaryotic and eukaryotic.
- Prokaryotic cells do not have a defined nucleus or a nuclear membrane; their genetic material is not enclosed within a membrane.
- Eukaryotic cells have a defined nucleus that is surrounded by a nuclear membrane.

### Step 2: Identify the Organisms
- The question lists four organisms: Penicillium, Agaricus, Volvox, and Nostoc.
- **Penicillium**: This is a fungus, which is a eukaryotic organism. It has a nuclear membrane.
- **Agaricus**: Commonly known as mushroom, it is also a fungus and thus a eukaryotic organism with a nuclear membrane.
- **Volvox**: This is a green algae, which is classified as a protist and is also a eukaryotic organism with a nuclear membrane.
- **Nostoc**: This is a type of bacterium, which is prokaryotic and does not have a nuclear membrane.

### Step 3: Conclusion
- Since Nostoc is a bacterium, it is classified as a prokaryotic cell and therefore lacks a nuclear membrane.
- The correct answer to the question "Nuclear membrane is absent in" is **Nostoc**.

### Final Answer:
**Nostoc**

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