Question

One of the following statement is not true with respect to red muscle fibres

• A. Faster in contraction rate
• B. Rich in mitochondria
• C. Rich in myoglobin
• D. Carry out aerobic contraction without accumulating much lactic acid

Answer 1

Answer: (B), (C), (D)

Faster in contraction rate

Answer 2

Red muscle fibres, also known as slow-twitch muscle fibres, are adapted for sustained, prolonged activity.

1. Faster in contraction rate: This statement is incorrect. Red muscle fibres are characterized by a slower contraction rate but are resistant to fatigue. White muscle fibres (fast-twitch) have a faster contraction rate.
2. Rich in mitochondria: This statement is correct. Red muscle fibres are rich in mitochondria, which are essential for aerobic respiration to produce ATP for sustained activity.
3. Rich in myoglobin: This statement is correct. Myoglobin is a red pigment that stores oxygen, giving these muscles their characteristic red color and enabling efficient aerobic respiration.
4. Carry out aerobic contraction without accumulating much lactic acid: This statement is correct. Due to their high mitochondrial content, rich blood supply, and myoglobin, red muscle fibres primarily rely on aerobic metabolism. This process efficiently produces ATP without significant accumulation of lactic acid, which is a byproduct of anaerobic metabolism.

Therefore, the statement that is not true with respect to red muscle fibres is (1).