1. By Group 3 of 7W Joey Li, Benson Lau, Ronald Lee, Terry,

2. Viruses Viruses do not respire, move, grow or feed outside a living cell and so show very limited characteristics as living things. However they reproduce very rapidly inside human body cells taking over the function of the nucleus and forcing the cell to make more viruses and thereby spreading the infection.

3. Bacteria are cell-based organisms that are very much larger than viruses. They do respire, move, grow, feed and reproduce. In dry conditions, they can survive by producing hard coats and becoming inactive as spores. Spores are easily spread in the air. Bacteria

4. Fungi Fungi are cell-based organisms similar to bacteria. They like the moist skin areas of the body.

5. Common infectious diseases Some information below, which shows six common infectious diseases, the part of the body affected, and the infective agent or pathogen which causes the illness - either Bacterium, Fungus or Virus. Infectious Disease Site of body infection Pathogen. Athlete's foot Moist skin Fungus Common cold Nasal passages Virus HIV Body immune system Virus Influenza (flu) Nasal passages Virus Tuberculosis (TB) Lungs Bacterium Salmonella Digestive system Bacterium