SSC MTS EXAM

Detailed explanation-1: -The formation of a bivalent occurs during the first division of meiosis (in the zygotene stage of meiotic prophase 1). In most organisms, each replicated chromosome (composed of two identical sister chromatids) elicits formation of DNA double-strand breaks during the leptotene phase.

Detailed explanation-2: -Prophase I During zygotene, homologous chromosomes begin to align along their entire length by a process called synapsis that is necessarily precise. Each pair of chromosomes is held together by a ribbon-like protein and forms the synaptonemal complex.

Detailed explanation-3: -The formation of a bivalent occurs during the pachytene stage. During this stage, chromosomal condensation makes it possible for the chromosomes to be viewed under the microscope.