Select the odd one out w.r.t porins

Options

A. Not associated with the inner membrane of plastids
B. Associated with the outer membrane of mitochondria
C. Found in outer membrane of gram positive becteria
D. Allow movement of low molecular weight hydrophillic substances .

Answer

To solve the question "Select the odd one out with respect to porins," we will analyze each option provided in the question and determine which one does not fit with the characteristics of porins.

### Step-by-Step Solution:

1. **Understanding Porins**:
- Porins are beta-barrel proteins that form channels in cellular membranes, allowing for the passive diffusion of molecules, particularly low molecular weight hydrophilic substances.

2. **Analyzing Each Option**:
- **Option 1**: "Not associated with inner membrane of plastid"
- This statement is true. Porins are typically associated with the outer membrane of organelles like mitochondria and not with the inner membrane of plastids.

- **Option 2**: "Associated with outer membrane of mitochondria"
- This statement is also true. Porins are indeed found in the outer membrane of mitochondria, allowing for the passage of small molecules.

- **Option 3**: "Found in outer membrane of gram-positive bacteria"
- This statement is true as well. Porins are present in the outer membrane of gram-negative bacteria, but the term can sometimes be loosely applied in discussions about gram-positive bacteria, although they typically do not have an outer membrane like gram-negative bacteria.

- **Option 4**: "A low movement of low molecular weight hydrophilic substances"
- This statement is true. Porins facilitate the movement of low molecular weight hydrophilic substances across membranes.

3. **Identifying the Odd One Out**:
- After analyzing all the options, the statement "Found in outer membrane of gram-positive bacteria" is the odd one out. While porins are found in bacteria, they are primarily associated with gram-negative bacteria. Gram-positive bacteria do not have an outer membrane in the same way, making this statement less accurate in the context of porins.

### Conclusion:
The odd one out with respect to porins is: **"Found in outer membrane of gram-positive bacteria."**

---