Now that we know about both prokaryotic and eukaryotic cells, let's look at the endosymbiosis theory. This theory suggests that mitochondria and plastids in eukaryotic cells were once independent prokaryotic cells.
Avian influenza (AI) is an infectious viral disease of birds (especially wild water fowl such as ducks and geese), often causing no apparent signs of illness. AI viruses can sometimes spread to domestic poultry and cause large-scale outbreaks of serious disease.
Government site for Avian Influenza and Pandemic Influenza Information at http://www.pandemicflu.gov/ Avian Influenza is a viral disease of wild and domestic birds. It can cause illness in poultry and humans. Photo from USDA OnLine Photography Center.