|MadSci Network: Anatomy|
No, gelatin is not a good substitute for human skin. It does not have all of the chemicals found in human skin and you can therefore not accurately test the effects of certain chemical with the enzymes and other chemicals. Also gelatin does not have the pores and hairs of human skin therefore you cannot accurately test these chemicals either. Ask your teacher for more assistance.
Try the links in the MadSci Library for more information on Anatomy.