Reasons why a transport system is necessary in higher animals?

Explanation:

The higher animals needs and internal transport system so that the innermost cells can get nutrition which cannot be left on diffusion and osmosis to transmit. They also needed an internal transport system and so that they get oxygen to the internal cell...

I hope you help :)

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products