Mitochondria/Myoglobin level in Type 2b fibres is low.

Mitochondria/Myoglobin level in Type 2b fibres is low.

• A. High
• B. Low
• C. Medium
• D. None

Answer: (B)

The main idea is how muscle fibre types determine energy systems. Type 2b fibres are fast-twitch glycolytic fibres designed for quick, powerful bursts. They generate most of their ATP through anaerobic glycolysis rather than aerobic respiration. Because oxidative metabolism isn’t the main energy source for these fibres, they contain fewer mitochondria and less myoglobin, which stores and helps transport oxygen for use in mitochondria. That’s why their levels of mitochondria and myoglobin are low. This matches the statement. High or medium levels would be more typical of fibres that rely more on aerobic metabolism.

The main idea is how muscle fibre types determine energy systems. Type 2b fibres are fast-twitch glycolytic fibres designed for quick, powerful bursts. They generate most of their ATP through anaerobic glycolysis rather than aerobic respiration. Because oxidative metabolism isn’t the main energy source for these fibres, they contain fewer mitochondria and less myoglobin, which stores and helps transport oxygen for use in mitochondria. That’s why their levels of mitochondria and myoglobin are low. This matches the statement. High or medium levels would be more typical of fibres that rely more on aerobic metabolism.