Which of the following statement holds true for haemoglobin if the `Pco_(2)` increases ?

Options

A. It must be exposed to a higher partial pressure of oxygen in order to become fully saturated
B. It will tend to release its oxygen at higher partial pressure of carbon dioxide.
C. It becomes less efficient at taking up oxygen and more efficient at releasing it.
D. All of these

Answer

To answer the question regarding the effects of increased partial pressure of carbon dioxide (Pco2) on hemoglobin, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Hemoglobin's Function**: Hemoglobin is a respiratory pigment found in red blood cells that binds to oxygen (O2) and transports it to tissues throughout the body. It forms a complex called oxyhemoglobin when bound to oxygen.

2. **Effect of Pco2 on Hemoglobin**: The binding of oxygen to hemoglobin is influenced by several factors, one of which is the partial pressure of carbon dioxide (Pco2). An increase in Pco2 indicates a higher concentration of carbon dioxide in the blood.

3. **Impact of Increased Pco2**:
- When Pco2 increases, the affinity of hemoglobin for oxygen decreases. This means that hemoglobin is less likely to bind to oxygen.
- The increased concentration of carbon dioxide promotes the release of oxygen from hemoglobin. This is known as the Bohr effect, where higher levels of carbon dioxide and lower pH (due to increased carbonic acid formation) lead to a decrease in hemoglobin's oxygen-binding capacity.

4. **Dissociation of Oxyhemoglobin**: As a result of the increased Pco2, oxyhemoglobin dissociates more readily, releasing oxygen into the tissues that require it. This is particularly important in metabolically active tissues where carbon dioxide production is high.

5. **Conclusion**: Therefore, if Pco2 increases, hemoglobin becomes less efficient in taking up oxygen and more efficient in releasing it. This means that while hemoglobin's ability to bind oxygen decreases, its ability to release oxygen to tissues increases.

### Final Answer:
The correct statements regarding hemoglobin when Pco2 increases are:
- Oxygen will be released at high Pco2 pressure.
- It will be less efficient in taking up oxygen and more efficient in releasing it.