The modern classification is based on a six Kingdom system-
<span>1- Animalia</span>
2- Plantae
3- Fungi
4- Protista
5- Archaea bacteria
6- <span>Eubacteria </span>
Doctors inject medicines in veins because veins are more accessible and donot have high pressure due to which there is no risk of blood backing up with into the infused fluid.
However there are some cases when medicine is injected in artery but a lot of precautions needs to be taken while doing so.
In facilitated diffusion.molecules only move with the aid of a protiein in the membrain simple diffusion is passive but facliitaed diffusion is an active process that uses energy simple diffusion requires molecules to move through special doorways in the cell membrane