Q.The pigment present in the muscle fibre to store oxygen is:

Myoglobin is the iron-containing pigment inside muscle fibres that binds and stores oxygen for use during muscle contraction.

Skeletal and cardiac muscle fibres contain myoglobin, a single-chain globular protein closely related in structure to one subunit of haemoglobin, but with a much higher affinity for oxygen. Because of this higher affinity, myoglobin readily takes up oxygen delivered by blood haemoglobin and holds it as a local reserve within the muscle cell (sarcoplasm). During strong or sustained contraction, when the oxygen supplied by blood momentarily falls short of demand, myoglobin releases its stored oxygen to the mitochondria, supporting continued aerobic respiration (ATP production) in the muscle fibre. Muscles that are used for prolonged/aerobic work (red or 'slow' fibres) are richer in myoglobin and appear dark red because of it, while muscles used for short bursts of activity (white or 'fast' fibres) contain less. The other options are unr …