In unicellular orgapisms, external transport is carried out through the plasma membrane, and internal – with the circular movement of the cytoplasm (cyclosis). In multicellular organisms, the cells are so far removed from each other that such delivery is ineffective, therefore, they have transport systems that ensure the transport of substances over considerable distances.
The transport of substances in the body ensures the delivery of the necessary compounds to organs, tissues and cells, as well as the removal of the harmful end products of metabolism formed in them.
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