Mark the odd one w.r.t. Characteristic features of human RBC

Options

A. Biconcave
B. Circular
C. Oval
D. Non nucleated

Answer

### Step-by-Step Solution:

1. **Understanding the Structure of RBCs**:
- Red blood cells (RBCs) are primarily characterized by their biconcave shape. This unique shape increases the surface area for gas exchange and allows them to deform as they pass through narrow capillaries.

2. **Identifying Key Features of RBCs**:
- RBCs are non-nucleated, meaning they do not have a nucleus. This is a significant feature that distinguishes them from other types of cells.
- They lack most organelles, which is another characteristic that allows them to maximize space for hemoglobin, the protein responsible for oxygen transport.
- RBCs perform anaerobic respiration. This is crucial because if they used oxygen for their own metabolism, it would defeat their primary function of transporting oxygen to other cells.

3. **Listing Common Characteristics**:
- Biconcave shape
- Non-nucleated
- Lack of organelles
- Presence of hemoglobin
- Perform anaerobic respiration

4. **Identifying the Odd One Out**:
- Among the characteristics listed, if we consider a feature that does not belong to the RBCs, we can identify that they are not circular or oval in shape. This is the odd one out because the defining characteristic of RBCs is their biconcave shape.

### Conclusion:
The odd one out with respect to the characteristic features of human RBCs is that they are not circular or oval in shape.