Final answer:
In a typical mammalian adult cell, the M phase occupies a very small fraction of the cell cycle, lasting only about 0.5 hours in a cycle that typically spans 24 hours.
Step-by-step explanation:
The statement is false; in a typical mammalian adult cell, the M phase does not take up a large fraction of the entire cell cycle. Most mammalian cells are in interphase, and only a small percentage are actually in mitosis.
When mammalian cells are in a rapidly dividing state, the length of the cell cycle is about 24 hours, wherein the M phase lasts approximately only 0.5 hours. This is quite short compared to the other phases such as the G1 phase and S phase, which last 9 hours and 10 hours respectively.