Question

Why is diffusion is not sufficient to meet the oxygen requirements of all the cells in multicellular organisms?

Answer 1

In multicellular organisms all the cells may not be direct contact with the surrounding environment. Thus, simple diffusion will not meet the requirements of all the cells because diffusion is very slow process.

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.