Regarding the the differences between DNA and RNA viruses, it is interesting to note that DNA virus genomes can be larger than RNA virus genomes. This is possible because DNA polymerases proofread and correct mistakes while RNA replicases and polymerases do not.

This is an example of how a fact, which may not be so crucial in itself, can help you retain something more important by giving it context. In this case, an insight into viruses helps you peg an important difference between the processes of DNA and RNA replication. DNA is replicated with proofreading but RNA is replicated without proofreading.