Witch is as example of making a qualitative observation

Explanation:

Example of making qualitative observation is that as i observed that one litre of water weighs 1000g and one litre of ethanol weighs 789g so it is an example of quantitaive observation

i think it is dna, i'm not totally sure but i think it might be.

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.