In birds and mammals the left and right side of the heart are separated. Give reasons.

Explanation

### Step-by-Step Solution:

1. **Understanding Heart Structure in Birds and Mammals**:
- Birds and mammals have a four-chambered heart, which includes two atria and two ventricles. This structure allows for the separation of oxygenated and deoxygenated blood.

2. **Importance of Separation**:
- The separation of the left and right sides of the heart is crucial for efficient circulation. The left side of the heart pumps oxygen-rich blood to the body, while the right side pumps oxygen-poor blood to the lungs for oxygenation.

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