Question

Give two reason that the big animals contain respiratory pigments.

Answer 1

•A respiratory pigment is a molecule, such as hemoglobin in humans and other vertebrates, that increases the oxygen-carrying capacity of the blood.

•Animals have large body size due to which diffusion alone cannot meet the oxygen requirement of the whole body. Therefore respiratory pigment take up oxygen from lungs and carry it to tissues.

Answer 2

1) simple diffusion is not possible in multicellular organisms. hence to take oxygen from skin is impossible

2) oxygen doesn't dissolve easily in blood, hence to increase efficiency of transport of oxygen, respiratory pigments are used.

in humans, the respiratory pigment is haemoglobin which has high affinity for oxygen.