Biological Systems MCAT Practice Exam 2026 – The Comprehensive All-in-One Guide for Exam Success!

Myoglobin's primary function in muscle tissues is to store oxygen. This protein binds to oxygen molecules and provides a reservoir of oxygen that can be readily available for the muscle cells, particularly during periods of increased metabolic demand, such as during intense exercise.

While the muscles primarily obtain energy through the metabolism of glucose and fats for ATP production, myoglobin plays a crucial supportive role by ensuring sufficient oxygen supply, especially in scenarios where the energy demands exceed what can be met by blood oxygen levels alone. This is particularly important in skeletal muscle and cardiac muscle, where a rapid supply of oxygen can enhance endurance and overall performance.

Myoglobin also has a higher affinity for oxygen compared to hemoglobin, the protein responsible for oxygen transport in the bloodstream. This allows myoglobin to effectively extract oxygen from hemoglobin and store it for muscle use. Hence, the correct answer aligns with myoglobin's function as an oxygen storage protein, crucial for sustaining muscle function during anaerobic conditions when oxygen levels may drop significantly.