The respiratory quotient value of 0.9 is obtained for

Options

A. Anaerobic respiration
B. Glucose
C. Proteins
D. Organic acids.

Answer

To determine the respiratory quotient (RQ) value of 0.9, we need to understand what RQ represents and how it varies with different substrates used in respiration. Here’s a step-by-step breakdown:

### Step 1: Understand the Definition of RQ
The respiratory quotient (RQ) is defined as the ratio of the volume of carbon dioxide (CO2) produced to the volume of oxygen (O2) consumed during respiration. The formula is:
\[ RQ = \frac{Volume \, of \, CO2 \, produced}{Volume \, of \, O2 \, consumed} \]

**Hint:** RQ indicates the type of substrate being metabolized during respiration.

### Step 2: Identify RQ Values for Different Substrates
Different substrates yield different RQ values:
- **Carbohydrates:** RQ = 1 (equal amounts of CO2 produced and O2 consumed)
- **Fats:** RQ = 0.7 (less CO2 produced compared to O2 consumed)
- **Proteins:** RQ = 0.9 (CO2 produced is slightly less than O2 consumed)
- **Organic acids:** RQ > 1 (more CO2 produced than O2 consumed)

**Hint:** Memorizing these values can help in quickly identifying the substrate based on the RQ value.

### Step 3: Analyze the Given RQ Value
The question specifies an RQ value of 0.9. Referring to the RQ values identified in the previous step, we see that:
- The RQ value of 0.9 corresponds to the metabolism of **proteins**.

**Hint:** Focus on the RQ value that matches the given number to identify the correct substrate.

### Step 4: Eliminate Other Options
Now, let's consider the other options:
- **Anaerobic respiration:** This has an RQ value of infinity since no oxygen is consumed.
- **Carbohydrates:** This has an RQ value of 1.
- **Organic acids:** This has an RQ value greater than 1.

Since none of these options match the RQ value of 0.9, we confirm that the correct answer is proteins.

**Hint:** Always compare the given RQ value with known values to eliminate incorrect options.

### Conclusion
The respiratory quotient value of 0.9 is obtained for **proteins**.

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