In order to see where viruses, viroids and prions fit into the scheme of life, we need to know what life is and what the properties of life are. The capabilities of viruses, viroids and prions and the diseases they cause. Should they be considered 'alive' if they only contain a few of life's properties because their survival depends on other living cells.
Life consists of living things and these living things have cells that have the capacity for "order, reproduction, growth and development, energy utilization, evolutionary adaptation, response to the environment and homeostasis" (Campbel…
