What do live animals produce that is another reservoir of nitrogen?

In this case, the statement that people who exercise for an hour may have lower cholesterol levels is .

Matthew decided he wanted to hike up mount everest. on his way to the top, it began to snow and the temperature dropped to -10°f. matthew forgot to wear a heavy jacket so his body began to shiver beyond control. in this case, matthew's body shivering is the to a drop in temperature. * 0 points reflex stimuli responce environmental facto

What is the one part of the nucleotide  that differs among the other different nucle  tides?