Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): During the pachytene stage of meiosis I, recombination nodules appear on the bivalents. Reason (R): Recombination nodules represent the sites where crossing over occurs between sister chromatids of homologous chromosomes. In the light of the above statements, choose the most appropriate answer from

Step-by-step solution

Assertion (A) is true: During the pachytene stage of prophase I in meiosis I, the bivalent chromosomes clearly appear as tetrads and this stage is characterised by the appearance of recombination nodules. Reason (R) is false: Recombination nodules represent the sites where crossing over occurs, but crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes, not sister chromatids. A common mistake is failing to distinguish between sister and non-sister chromatids; excha