During meiosis I, the chromosomes start pairing at
- zygotene
- pachytene
- diplotene
- leptotene.
Answer
(1) zygotene
Solution
As per NCERT, during zygotene (the second stage of prophase I) chromosomes start pairing together; this process of association is called synapsis, accompanied by the formation of the synaptonemal complex.
∵ Chromosomes become visible in leptotene, crossing over occurs in pachytene and the paired chromosomes begin to separate in diplotene, options (2), (3) and (4) are wrong.
Answer: (1)