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.
Avian flu, like other types of influenza, is caused by a virus that infects the respiratory system. As a result, effects on the body often focus on the throat, nose, and lungs. The nose may become congested, the throat may become sore, and a cough or sore throat may occur. A fever and muscle aches may occur.