Question

Red muscle fibres have ______ myoglobin than white muscle fibre.

• A. higher
• B. lower
• C. dense
• D. thin

Hint:

Associate the color with the function: \textbf{Red} = Rich in myoglobin/oxygen = Endurance (slow-twitch). \textbf{White} = Low in myoglobin/oxygen = Speed/Power (fast-twitch). Think of the dark meat (legs) vs. white meat (breast) in a chicken.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Muscle fibres are categorized based on their contraction speed and primary mode of ATP production. The two main types are red (slow-twitch) and white (fast-twitch) muscle fibres.
Myoglobin is an iron- and oxygen-binding protein found in the muscle tissue of vertebrates. Its primary function is to store and supply oxygen to the muscle cells.
Step 3: Detailed Explanation:
Red muscle fibres (Type I) are adapted for sustained, long-duration activities like long-distance running. They rely on aerobic respiration, which requires a constant and abundant supply of oxygen. To facilitate this, they have a high concentration of myoglobin, which stores oxygen within the muscle cell. The high myoglobin content, along with a rich blood supply, gives these fibres their characteristic red color.
White muscle fibres (Type II) are adapted for short, rapid, powerful bursts of activity like sprinting. They primarily rely on anaerobic glycolysis for energy, which does not require oxygen. Consequently, they have a much lower concentration of myoglobin, giving them a paler or white appearance.
Step 4: Final Answer:
Red muscle fibres are specialized for aerobic activities and thus have a higher concentration of the oxygen-storing protein myoglobin compared to white muscle fibres. Therefore, option (A) is correct.