The Importance of Transport System in Multicellular Organisms

  1. The transport system in humans and animals is the circulatory system.
  2. The transport system in plants is the vascular tissues.
  3. The vascular tissues consist of 
    1. xylem tissues and 
    2. phloem tissues.

Live Process of Cells

  1. Every cell in an organism need to obtain nutrients and oxygen from the environment and at the same time, is able to remove the waste products from the cell.
  2. Unicellular organisms obtain their nutrients and oxygen across the plasma membrane directly from the environment by diffusion.
  3. Unicellular organisms are small in size. As a result, they have a large total surface area to volume (TSA/V) ratio. This enables the exchange of substances to occur rapidly by diffusion.

Why the Transport System is Important for Multicellular Organism?

  1. Multicellular organisms are bigger and hence have a small total surface area to volume (TSA/V) ratio. As a result, the rate of diffusion of substances is low. The larger the organism, the more difficult it is for the substances to diffuse in and out of the body cells.
  2. Also, as the size of an organism increases, the amount of nutrients and oxygen gas needed also increases. So does the metabolic waste products. As such, diffusion alone is not sufficient to fulfill the needs of the body cells and to remove the waste products from the body.
  3. Other than that, for a multicellular organism, the cells are located further in the body. They are not directly in contact with the environment.
  4. Therefore, multicellular organisms need special transport systems to transport the nutrients to all the body cells and at the same time to remove the metabolic waste from the body cells.