Answer:
A disease model is an animal or cells displaying of the pathological process that are observed in the actual human or animal disease.
Explanation:
Desert
Cactus-butterfly-lizard-snake
In a closed ecological system, any waste products produced by one species must be used by at least one other species. If the purpose is to maintain a life form, such as a mouse or a human, waste products such as carbon dioxide, feces and urine must eventually be converted into oxygen, food, and water.