The decline of MPF activity at the end of mitosis is due to a. the destruction of the protein kinase Cdk. b. decreased synthesis of Cdk. c. the degradation of cyclin. d. the accumulation of cyclin.

Maturation Promoting Factor (MPF) is a complex of cyclin and cyclin-dependent kinase (Cdk) that regulates the cell cycle, particularly the transition from G2 phase to mitosis. MPF activity is crucial for the initiation of mitosis, and its levels fluctuate throughout the cell cycle, peaking during mitosis.

Cyclins are regulatory proteins whose levels rise and fall throughout the cell cycle. At the end of mitosis, cyclins are targeted for degradation, leading to a decrease in MPF activity. This degradation is essential for the exit from mitosis and the progression into the next cell cycle phase.

Cyclin-dependent kinases (Cdks) are enzymes that, when activated by binding to cyclins, phosphorylate target proteins to drive the cell cycle forward. The activity of Cdks is tightly regulated by the availability of cyclins and their degradation, which is critical for ensuring proper cell cycle progression and preventing uncontrolled cell division.