Question

Crossing over takes place on

• A. Two stranded stage
• B. Three stranded stage
• C. One stranded stage
• D. Four stranded stage

Answer 1

The correct option is D Four stranded stage

Crossing over takes place during the pachytene stage. During this stage non-sister chromatids of homologous chromosomes may exchange segments over regions of homology. Sex chromosomes, however, are not wholly identical, and only exchange information over a small region of homology. At the sites where exchange happens, chiasmata form. The exchange of information between the non-sister chromatids results in a recombination of information; each chromosome has the complete set of information it had before, and there are no gaps formed as a result of the process.