1. Which are the two important roles of the atmosphere?

The important role of the atmosphere is to supply oxygen, water, carbon dioxide and nutrients. It also protects all living things from extreme temperatures and radiation (protects us from harmful solar rays).

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

The answer to this will be from your lab notes/procedure. it would be best to ask another student who participated in the lab as we do not know what was done, what enzyme or if the temperature is celsius or fahrenheit. if i were to guess though i'd say the rate stopped due to enzyme denturing at high temperature