- A Cyclin B synthesis occurring continuously throughout the entirety of mitosis
- B APC/C (anaphase-promoting complex) activation by Cdc20, degrading cyclin B and securin
- C Activation of CDK1 at the G2 to M phase boundary without any further checkpoint regulation required afterward
- D Complete assembly of an entirely new mitotic spindle built independently at each subsequent round of division
Correct answer: B. APC/C (anaphase-promoting complex) activation by Cdc20, degrading cyclin B and securin
Explanation: APC/C-Cdc20 ubiquitinates cyclin B (inactivating CDK1) and securin (releasing separase). Both are degraded by the proteasome, triggering anaphase.
Concept context
Mitosis and meiosis: how cells divide for growth, repair, and reproduction.