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.
Bird Flu (Avian Flu) Overview. Bird flu (also termed avian influenza) is an illness that affects wild and domesticated birds that usually causes either little or no symptoms unless the bird population is susceptible, in which it may cause death in birds within about 48 hours.