During meiosis I, the complex formed by a pair of synapsed homologous chromosomes is called a bivalent. In which stage of prophase I do the four chromatids of each bivalent become distinct and clearly appear as tetrads?

Step-by-step solution

According to NCERT, during the zygotene stage, homologous chromosomes start pairing together to form bivalents. However, these bivalents are not clearly visible at this stage. The first two stages of prophase I (leptotene and zygotene) are relatively short-lived compared to the next stage, which is pachytene. During the pachytene stage, the four chromatids of each bivalent chromosome become distinct and clearly appear as tetrads. Students often confuse the formation of bivalents (zygotene) with their clear visibili