(a) Anti- bacterial medicines function by destroying the cell walls of the bacteria while in case of viruses, they do not have a mechanism of their own, and they need some host cell to replicate themselves. They attach their DNA with the DNA of the host cell for replication, so if we want to kill the viral DNA we will have to kill own cell.

(b) If a disease occurs for a short period of time but has a sudden onset and is severe, then it is termed as acute disease, example, a broken bone while chronic cases are the ones which last for a long period of time, example, osteoporosis. So, chronic diseases cause more harm to the body than acute diseases.