Systems in nature tend to undergo changes that result in

Explanation:

Entropy is a measure of the disorder in the system and in nature, systems favor a state of greater randomness or disorder and hence a higher entropy

In nature, systems tend to go from a higher energy state to a lower energy state

Reactions are always spontaneous if they are exothermic and go toward a higher entropy (in exothermic heat is released)

Reactions are never spontaneous if they are endothermic and go towards a lower entropy  (in endothermic heat is absorbed)

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.