Many cave organisms are blind. In fact, for many, their eyes have become vestigial structures (structures that are non-useful). How would an evolutionary biologist explain how this inability to see evolved from sighted ancestors?

compost can be added to topsoil as a:

pesticide

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.