Question

Which one is a mismatch? A. Haemoglobin-Frog B. Myoglobin- Mollusca C. Haemocyanin-Snail D. Hemoerythrin- Sipunculus

Answer 1

Hint: There are different respiratory pigments found in the organisms like haemoglobin, haemocyanin and hemoerythrin. They help in the binding of oxygen at a particular oxygen binding site linked with the metal atom in their structure.

Complete answer:
Frog are amphibians with a closed circulatory system. Frog contains a single heart which helps in pumping blood to the body. It contains 3 chambered hearts with 2 atria and ventricles. There is a systematic circuit which helps in the pumping of oxygenated blood throughout the body. The pulmonary circuit helps the blood in picking the oxygen. Frogs erythrocyte contains nucleated RBC with elliptical shape and capable of dividing easily. Erythrocytes is the carrier of haemoglobin. In humans there is no nucleus in the red blood cells. Frogs can easily breathe inside the water and also in air so they do not require much oxygen and hence the nucleus is present inside their red blood cells. So it is correct that Frog contains haemoglobin.
Mollusca contains soft- body with head, foot, and mantle and is shielded with exoskeleton shells. Mollusca are unsegmented, bilaterally symmetrical and triploblastic in nature. The common respiratory of mollusca contains gills and lungs. The respiratory pigment in the blood of mollusca is haemocyanin. Common mollusca include Snails, Clams
Myoglobin is found in vertebrates it contains iron and oxygen binding proteins present in red blood cells. Myoglobin is present in muscle tissue of vertebrates. So the mollusca do not contain myoglobin. So Myoglobin is not found in Mollusca.
Sipunculus is an unsegmented, bilaterally symmetrical marine worm. Around 300 species of Sipunculus are known. It is also known as peanut worm as it resembles a peanut. The organism contains true coelom with no circulatory system in them. Hemoerythrin helps them in carrying the oxygen. The evolutionary history about Sipunculus is it is related to the annelids. Hemoerythrin is the non- heme respiratory pigment in annelids. These are very limited and only contain three or four invertebrates phyla.

Hence, the correct answer is option (B).

Note: Respiratory pigments help in oxygen transport, blood buffering, carbon dioxide transport. Haemoglobin is the respiratory pigment which contains heme which is the iron porphyrin and the globin is a protein. Hence the molecules contain heme bonded with the protein. It is found in the red blood cells of both vertebrates and invertebrates. Haemocyanin have copper colour but when they are oxygenated they change into blue colour. Mainly found in arthropoda and mollusca. Hemoerythrin is the iron containing pigment found in very invertebrates.