Assertion : A sigmoid curve is obtained when percentage saturation of haemoglobin with `O_(2)` is plotted against the `PO_(2)`.
Reason : Every `100` mL of oxygenated blood can deliver around `5mL` of `O_(2)` to the tissues under normal physiological conditions.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true and reason is not the correct explanation of assertion
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To analyze the assertion and reason provided in the question, we can break it down step by step:

### Step 1: Understanding the Assertion
The assertion states that a sigmoid curve is obtained when the percentage saturation of hemoglobin with oxygen (O₂) is plotted against the partial pressure of oxygen (PO₂).

- **Explanation**: The sigmoid curve, also known as the S-shaped curve, represents the relationship between the partial pressure of oxygen and the saturation of hemoglobin with oxygen. This curve indicates that at low PO₂ levels, hemoglobin binds oxygen slowly, but as PO₂ increases, hemoglobin's affinity for oxygen increases rapidly until it reaches a plateau at high PO₂ levels.

### Step 2: Understanding the Reason
The reason states that every 100 mL of oxygenated blood can deliver around 5 mL of O₂ to the tissues under normal physiological conditions.

- **Explanation**: This statement reflects the oxygen delivery capacity of blood. Under normal conditions, the oxygen content in arterial blood is such that it can release approximately 5 mL of oxygen per 100 mL of blood to the tissues. This is crucial for cellular respiration and energy production in tissues.

### Step 3: Evaluating the Relationship between Assertion and Reason
Now, we need to determine if the reason supports the assertion.

- The assertion describes the relationship between PO₂ and hemoglobin saturation, while the reason describes the oxygen delivery capacity of blood. Both statements are true, but they address different aspects of oxygen transport and utilization in the body.

### Conclusion
- **Assertion**: True
- **Reason**: True
- **Relationship**: The reason does not directly support the assertion, as they discuss different concepts.

### Final Answer
Both the assertion and reason are true, but the reason does not explain the assertion.

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