Question

in multicellular organisms why the diffusion cannot take care of oxygen delivery to all parts of body​

Answer 1

In multicellular organisms diffusion can't fullfill the oxygen requirements because in multicellular organisms the cells of the body are not always in the contact of the outer environment thus diffusion can't take care of oxygen in the body.

Answer 2

In multicellular organisms like human beings diffusion is insufficient to meet the oxygen requirements of the body because of the following reasons :

• Diffusion is a very very slow process. Thus it can't fulfil the requirements of our body.

• The oxygen in human beings will have to travel last distances inside our body to reach each and every part of the cells.

• The volume of human body is so big that oxygen cannot diffuse into all the internal cells of the human body quickly.

• Also this is the reason for why the respiratory pigments are present in multicellular organisms also.