Darwin's theory. In 1859, Charles Darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. He defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".
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.
Carbon dioxide.
a gas produced by animals during respiration that plants use to make food, water, and oxygen.
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