Because viruses have the ability to infect cells. E.G a dendritic cell. So the only thing that can kill then are natural killer cells but then viruses reproduct in these cells
Metabolism is the chemical process that occur within a living organism in order to maintain life.
The replicated strand of DNA is. ATA-ATC-TAA-TGT
Adenine pairs with Thymine
Guanine pairs with Cytosine
If you have trouble remembering just think about it as curvy letters stick together(C,G), and straight letters go together (A,T)