Cell wall is absent in:

Options

A. Aspergillus
B. Funaria
C. Mycoplasma
D. Nostoc

Answer

To determine which organism lacks a cell wall from the given options, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Identify the First Option: Aspergillus**
- Aspergillus is a type of fungus.
- Fungi have a cell wall made of chitin.
- Therefore, **Aspergillus has a cell wall**.

2. **Identify the Second Option: Funerea**
- Funerea is a bryophyte, which belongs to the plant kingdom.
- Plants have a cell wall made primarily of cellulose.
- Therefore, **Funerea has a cell wall**.

3. **Identify the Third Option: Mycoplasma**
- Mycoplasma are known to be the smallest free-living organisms and are classified as bacteria.
- They are unique because they **lack a cell wall** entirely.
- This absence of a cell wall gives them no definite shape.
- Therefore, **Mycoplasma does not have a cell wall**.

4. **Identify the Fourth Option: Nostoc**
- Nostoc is a type of cyanobacteria.
- Cyanobacteria have a cell wall made of peptidoglycan.
- Therefore, **Nostoc has a cell wall**.

### Conclusion:
After analyzing all the options, we find that the organism which **lacks a cell wall** is **Mycoplasma**. Thus, the correct answer is **Mycoplasma**.