Which phase determines the length of whole cell cycle? （ ） A. G1 phase B. G2 phase C. M phase D. S phase

D

Explanation:

The S phase determines the length of the whole cell cycle.

The S phase of the cell cycle is the phase during which the cell's DNA is replicated in the nucleus while the centrosome is replicated in the cytoplasm. This phase determines the length of the whole cell cycle because the time it takes to replicate a DNA varies according to the total DNA present in the cell. The rate of DNA replication is relatively constant from cells to cells and species to species. Hence, the more the DNA, the longer the time it will take for its replication.

For example, if cell A and cell B are similar in every way except that A has higher amount of DNA than B, it will take a longer time for cell A to complete S phase than cell B. Therefore, cell A will have a longer cell cycle than cell B.

a bird that nests only in a particular tree species.