Although both Kingdoms of Plantae and Animalia have cells, tissues and organs; there are many differences within their cell physiology, development, biology and growth. Separated by about 1.5 billion years of evolutionary history, they are two major multicellular groups of the Domain Eukaryota, which share features such as mitochondria and nuclei, but has evolved their multicellular organization independently by using the same initial tool kit—the set of genes inherited from their common unicellular eukaryotic ancestor (Alberts 2002). Plant cells are large and rectangular and have a fixed shape, whereas animal cells are much smaller and circular. Both plant and animal cells have flexible membranes, but because plant cells are additionally encased