Question

why is diffusion insufficient to meet the oxygen requirement of multicellular organism like us

Answer 1

in multicellular organisms, all the cells may not be direct contact with the surrounding environment. so diffusion is insufficient to meet oxygen requirements of multicellular organisms like us.



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Answer 2

In unicellular organisms like amoeba the Protoplasm shows natural movements these movements are called Brownian movements because of which the nutrients and oxygen distributed throughout the Protoplasm equally.

Whereas, In multicellular organisms, like human beings it is very important that the oxygen should be distributed to each and every cell of the human body. So this made us to develop more complicated system for transportation of materials and oxygen. So human circulatory system is very complicated. So this is the reason why we have evolved to have a more complicated circulatory system for the transportation of the materials in human body.

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