[A]: RQ indicates type of substrate oxidised in cell respiration.
[R]: Proteins are used in protoplasmic respiration.

Options

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

Answer

To analyze the given statements regarding Assertion (A) and Reason (R), we will break down the concepts involved and evaluate their validity step by step.

### Step 1: Understand the Assertion (A)
- **Assertion (A)** states: "RQ indicates the type of substrate oxidized in cell respiration."
- **Explanation**: RQ, or respiratory quotient, is defined as the ratio of carbon dioxide produced to oxygen consumed during respiration. Different substrates (carbohydrates, fats, proteins) have different RQ values, which can help identify which substrate is being utilized for energy production.

### Step 2: Evaluate the Truth of Assertion (A)
- The assertion is **true** because RQ does indeed indicate the type of substrate being oxidized during cellular respiration. For example:
- Carbohydrates: RQ = 1
- Fats: RQ = 0.7
- Proteins: RQ = 0.9

### Step 3: Understand the Reason (R)
- **Reason (R)** states: "Proteins are used in protoplasmic respiration."
- **Explanation**: Protoplasmic respiration refers to the process where proteins are oxidized for energy, particularly when carbohydrates and fats are not available.

### Step 4: Evaluate the Truth of Reason (R)
- The reason is also **true**. Proteins can be utilized for energy through protoplasmic respiration, particularly in situations where other energy sources are depleted.

### Step 5: Determine the Relationship Between Assertion and Reason
- While both the assertion and reason are true, the reason does not directly explain the assertion. The assertion discusses RQ as a measure of substrate utilization, while the reason specifically mentions the use of proteins in respiration without linking it back to RQ.

### Conclusion
- The correct evaluation is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion. Therefore, the answer is that both statements are true, but the reason is not the correct explanation of the assertion.

### Final Answer
- **Assertion (A)** is true.
- **Reason (R)** is true, but it does not explain (A).