Answer:
A virus is a microscopic infectious organism that has the ability to recreate/replicate itself with nothing but the cells that are living in another organism. Viruses have the ability to infect anything, from plants to animals to humans. You have much more of a chance of this being fatal (to any of these life forms) if you have heart problems or vitamin deficiency.
The cleanliness of a ecosystem or how healthy it is. It determines how clean an environment/ecosystem is. You need all types of animals living there, therefore making it more healthy. The more healthy, the more we can say that it is biodiverse.
Take your shirt off, wave it round ya head like a helicopter