Question

In multiple crossing over, exchange occurs at:

Options

• Two points on the same chromosome pair

• Several points on non-homologous chromosomes

• Only one point between homologous chromatids

• Several points on the same chromosome

Answer 1

Multiple crossing over is marked by more than two chiasmata, so exchange of segments happens at several points on the same chromosome. Each additional exchange point adds a loop, producing the multiple loops appearance.