3.Each onion plant begins as a single cell containing 16 chromosomes. How many chromosomes are present in each of the cells that you observed

In somatic cells, 16 chromosomes are present whereas in sex cells, there is 8 chromosomes.

Explanation:

In the somatic cells, the replication of chromosomes occur and after the replication is completed, the parent cell is divided into two daughter cells having double number of chromosome by each daughter cell i.e. 16 chromosomes while on the other hand, in sex cells, first the parent cell divides into two daughter cells and after sometime, these daughter cells are again divided having total four daughter cells each receives half number of chromosomes i.e. 8 chromosomes.

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation:

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.