Reverse transcriptase is a useful enzyme to have when?

Reverse Transcriptase (RT) is essential for HIV replication because the viral RNA genome on its own is highly susceptible to degradation by intracellular RNases. RT rapidly makes a much more nuclease-resistant double-stranded DNA copy of the RNA template that later integrates to form the proviral DNA.

This molecule is used by retroviruses to create DNA by using mRNA as a template. We know that normally transcription is the synthesis of mRNA from DNA. This can be useful in bioengeneering when using a virus as a vector to alter the genetic material of the host.

it would be c. xylem.

what statement best describes the difference between the sympathetic and parasympathetic nervous systems?

the sympathetic nervous system prepares the body for intense physical activity and is often referred to as the fight-or-flight response. the parasympathetic nervous system has almost the exact opposite effect and relaxes the body and inhibits or slows many high energy functions.