Why do large organisms require a transport system?

1 Answer
Nov 16, 2015

Because the surface area to volume ratio of their body is very small.

Explanation:

Because the body is made of many cells which are connected to each other, there are many cells which are not in contact with the outer environment, so they cannot get their needs or get rid of their waste directly to the environment. This means there must be a way for these cells to do so in order to function properly. So a respiratory, digestive, and excretory systems are needed, and in order for the different materials to go from the cells to these systems or the other way round, circulatory systems are needed.