5) If a body cell contains 50 chromosomes, how many
will exist in its gametes?
25

25

Explanation:

gametes are haploid cells and body cells are diploid. when a diploid cell undergo meiosis it will produce haploid gametes with half number of chromosomes. in this case body cell has 50 chromosomes so their gametes have only 25 chromosomes.

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.