Question

Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?

Answer 1

Hint: Diffusion is the process in which the substance moves from its high concentration to its lower concentration.

Complete answer:
The process of diffusion is considered to be insufficient in order to meet all the requirements of oxygen in the body of multicellular organisms because in multicellular organisms, there are number of cells present and all the cells are not directly in contact with their surrounding environment and thus the diffusion of oxygen in all the cells of the body is not possible and thus multicellular organism have to adopt new ways in order to meet all the oxygen demands of the body.
The organisms are divided into unicellular or multicellular on the basis of the number of cells present in the body. Unicellular organisms are those organisms which have only one cell in the body and it is responsible for carrying out all the functions. In these organisms like amoeba, as they have only one cell present in body which have direct contact with the surrounding environment and thus the exchange or movement or flow of the substances can simply and directly takes place by the process of diffusion, these organisms do not require complex pathways for the transportation and exchange of substances between the organism’s body and environment. Thus diffusion is sufficient for these organisms but in multicellular organisms all the cells cannot directly exchange the materials with the environment so they require complex mechanisms.

Note: Diffusion and osmosis are almost similar processes to each other except that in osmosis a semipermeable membrane is present through which movement of water molecules takes place.