AP BIOLOGY

Detailed explanation-1: -Synapsis is the pairing of two homologous chromosomes that occur during meiosis. This takes place during the prophase stage of meiosis I. When homologous chromosomes pair, the homolouges cross over and exchange genetic material at certain points. This process is called crossing over.

Detailed explanation-2: -DNA replication precedes the start of meiosis I. During prophase I, homologous chromosomes pair and form synapses, a step unique to meiosis. The paired chromosomes are called bivalents, and the formation of chiasmata caused by genetic recombination becomes apparent.

Detailed explanation-3: -Synapsis takes place during the zygotene stage of prophase I of meiosis.

Detailed explanation-4: -During the middle of prophase I, homologous chromosome undergo synapsis, or pairing up. This is followed by an exhange of DNA between non-sister chromatids. This exchange is called recombination, or crossing over.