The correct option is Myoglobin.
Explanation
Respiratory pigments are specialized proteins containing metal ions that bind reversibly with oxygen. In vertebrates, distinct pigments are utilized for oxygen transport in the circulatory system and oxygen storage within tissues to support metabolic activities.Option Analysis:
- Myoglobin is Correct: Myoglobin is an iron-containing protein found primarily in the striated muscles of vertebrates. It serves as an oxygen-storing pigment, holding a reserve of oxygen within muscle cells to be used during periods of high metabolic demand or hypoxia. It is responsible for the red colour of muscle tissue.
- Hemoglobin is Incorrect: Hemoglobin is the red respiratory pigment found in Red Blood Cells (RBCs). Its primary function is the transport of oxygen from the lungs to various tissues, rather than storage within muscle cells.
- Melanin is Incorrect: Melanin is a pigment responsible for the colouration of skin, hair, and eyes. It acts as a protective shield against ultraviolet (UV) radiation and is not involved in oxygen binding or storage.
- Bilirubin is Incorrect: Bilirubin is a yellowish bile pigment produced during the breakdown of heme (from hemoglobin) in the liver. It is an excretory product rather than a functional respiratory pigment.
Key Takeaway:
Myoglobin is the oxygen-storing pigment located specifically in muscles, whereas Hemoglobin is the oxygen-transporting pigment found in the blood.