Answer: Synapsis completion and DNA double-strand break repair.
- A Overall chromosome condensation status during prophase
- B Synapsis completion and DNA double-strand break repair
- C Correct assembly of the meiotic spindle apparatus
- D Completion of cytoplasmic division during telophase
Correct answer: B. Synapsis completion and DNA double-strand break repair
Explanation: Pachytene checkpoint: monitors completion of synapsis and repair of meiotic DSBs (programmed by Spo11) before cells can proceed to metaphase I.
The cell cycle: G1 (growth and preparation), S (DNA replication, chromosome number stays 2n but DNA content doubles), G2 (final checks before division), and M (mitosis itself) - together, G1+S+G2 make up interphase.
Concept context
Mitosis and meiosis: how cells divide for growth, repair, and reproduction.