(1) Transport of materials is necessary for both plants and animals as every cell needs a regular supply of nutrients and oxygen for releasing energy through respiration.
(2) In plants, the transport of water and food is accomplished with the help of a complex transport system. Animals need to transport wastes to parts from where they can be removed.
(3) The cells of different organs of plants and animals need various necessary substances to carry out many metabolic activities and different types of waste products are created during these metabolic activities.
(4) So, transport of materials is necessary to supply the required substances and to remove the waste products.