Question

Why is respiratory pigment needed in multicellular organisms with large body size?

Answer 1

1. Haemoglobin and other respiratory pigments are crucial in oxygen delivery in large multicellular organisms. 
2. These pigments effectively supply oxygen to cells with high metabolic needs. 
3. Respiratory pigments sustain oxygen supply during metabolic processes by enhancing their capacity, overcoming diffusion restrictions, and functioning as reservoirs.