4. How might biotic and abiotic factors have affected the tortoises that Darwin observed on the Islands?

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The basic repeating unit of nucleic acids are known as nucleotides. a nucleotide consists of three distinct chemical groups.

When a virus infects a host cell, it uses the cell's machinery to make copies of its own genetic material in a process called replication. finally, during the process of self-assembly, that protein shell and the copies of the virus's genetic material are assembled into new viruses.