Which one is not the character of red skeletal muscles ?

Options

A. Smaller diameter
B. More mitochondria
C. More sarcoplasmic reticulum
D. More blood capillaries

Answer

To determine which characteristic is not associated with red skeletal muscles, let's analyze the options provided:

1. **Small Diameter**: Red skeletal muscles have a smaller diameter compared to white skeletal muscles. This is a characteristic of red skeletal muscles.

2. **Small Mitochondria**: Red skeletal muscles are known for having a higher number of mitochondria, which are larger in size compared to those in white skeletal muscles. Therefore, this statement is incorrect.

3. **More Mitochondria**: Red skeletal muscles contain more mitochondria than white skeletal muscles, which is a defining characteristic of red skeletal muscles.

4. **More Sarcoplasmic Reticulum**: Red skeletal muscles have less sarcoplasmic reticulum compared to white skeletal muscles. Thus, this statement is also incorrect.

5. **More Blood Capillaries**: Red skeletal muscles have a higher density of blood capillaries, which is another characteristic of red skeletal muscles.

Based on this analysis, the characteristic that is not associated with red skeletal muscles is **"small mitochondria"**.

### Step-by-Step Solution:
1. **Identify the Characteristics**: List the characteristics of red skeletal muscles.
2. **Evaluate Each Characteristic**: Compare each characteristic with known facts about red skeletal muscles.
3. **Determine the Incorrect Characteristic**: Identify which characteristic does not align with the properties of red skeletal muscles.
4. **Conclude**: State the characteristic that is not true for red skeletal muscles.