Read the following statement .
a) High `H^+` concentration and higher temperature are favourable for dissociation of oxygen from oxyhaemoglobin.
b) Partial pressure of oxygen in alveoli is higher than in tissue .
c) The maximum volume of air a person can breather in after a forced expiration is vital capacity.
d) In alveoli `PCO_2` low and `PO_2` high are for dissociation of `CO_2` from carbamino haemoglobin .
How many of the above statement are true ?

Options

A. One
B. Two
C. Three
D. Four

Answer

To determine how many of the given statements are true, we will analyze each statement one by one.

### Step 1: Analyze Statement a
**Statement a:** High `H^+` concentration and higher temperature are favourable for dissociation of oxygen from oxyhaemoglobin.

- **Explanation:** In physiological conditions, an increase in `H^+` concentration (lower pH) and higher temperature indeed promotes the dissociation of oxygen from oxyhemoglobin. This is known as the Bohr effect, where increased carbon dioxide and decreased pH (increased `H^+`) enhance oxygen release from hemoglobin. Therefore, this statement is **true**.

### Step 2: Analyze Statement b
**Statement b:** Partial pressure of oxygen in alveoli is higher than in tissue.

- **Explanation:** The alveoli are the primary site for gas exchange, where oxygen is abundant due to inhalation. In contrast, tissues utilize oxygen for metabolism, leading to a lower partial pressure of oxygen in tissues compared to the alveoli. Thus, this statement is also **true**.

### Step 3: Analyze Statement c
**Statement c:** The maximum volume of air a person can breathe in after a forced expiration is vital capacity.

- **Explanation:** Vital capacity is defined as the maximum amount of air a person can exhale after a maximum inhalation. Therefore, the statement is incorrect as it describes the wrong action (breathing in after forced expiration instead of exhaling). Hence, this statement is **false**.

### Step 4: Analyze Statement d
**Statement d:** In alveoli `PCO_2` low and `PO_2` high are for dissociation of `CO_2` from carbamino haemoglobin.

- **Explanation:** In the alveoli, the partial pressure of carbon dioxide (`PCO_2`) is indeed low due to its diffusion into the alveolar air, while the partial pressure of oxygen (`PO_2`) is high. This gradient allows for the dissociation of carbon dioxide from carbamino hemoglobin, facilitating gas exchange. Therefore, this statement is **true**.

### Conclusion
Now, let's summarize the truth values of the statements:
- Statement a: True
- Statement b: True
- Statement c: False
- Statement d: True

**Total True Statements:** 3

### Final Answer:
**3 statements are true.**

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