Question

Select the correct matched pair.
(1) S phase - DNA replication
(2) Zygotene - Synapsis
(3) Diplotene - Crossing over
(4) Meiosis - Both haploid and dipolid cells
(5) G${}_2$ phase - Quiescent stage

• A. (1) and (2) only
• B. (3) and (4) only
• C. (3) and (5) only
• D. (5) and (4) only

Answer 1

Answer: (A)

(1) and (2) only

A cell cycle comprises of interphase and division phase. The interphase is the longest phase of cell cycle. It comprises of first growth phase, S phase and second growth phase. The S phase is the synthesis phase in which DNA replication occurs. The meiotic division is carried out in two stages: meiosis I and meiosis II. The meiosis I comprises of prophase I, metaphase I, anaphase I and telophase I. The prophase I is very elaborate stage and comprises of several substages - leptotene, zygotene, pachytene, diplotene and diakinesis. The chromosomes coil at the leptotene stage. Homologous chromosomes pair at the zygotene stage. The pairing of homologous chromosomes is called as synapsis. This is followed by crossing over in the pachytene stage.