Question

Crossing over takes place attiring stage/phase

• A. S-phase
• B. Zygotene stage
• C. Pachytene stage
• D. $G_2$ - phase

Answer 1

Answer: (C)

Pachytene stage

The crossing over takes place during pachytene of prophase I of meiosis II. During this phase, chiasma is formed between non-sister chromatids of homologous chromosomes. S phase or synthetic phase is the period of DNA synthesis or replication. During this phase the amount of DNA per cell doubles. Zygotene is the second staged prophase I of meiosis II. During this stage, chromosome starts pairing together and this process of association is called synapsis. Such paired chromosome are called homologous chromosomes. Synapsis is accompanied by the formation of the complex structure called synaptonemal complex.

Numbers of chromosome remain same in G${}_2$ phase.

Thus, the correct answer is option C.