Bivalent or Tetrad formation is a characteristic feature observed during
- Chiasmata in zygotene stage
- Synaptonemal complex in zygotene stage
- Chiasmata in Diplotene stage
- Synaptonemal complex in Pachytene stage
Answer
(2) Synaptonemal complex in zygotene stage
Solution
As per NCERT, during zygotene homologous chromosomes start pairing (synapsis), accompanied by the formation of the synaptonemal complex.
The complex formed by a pair of synapsed homologous chromosomes is called a bivalent or a tetrad.
⇒ Chiasmata become visible only in diplotene, after the bivalents are already formed.
Answer: (2)