Question

Why is the onion root used to demonstrate mitosis?

Answer 1

is because of the meristematic cells that are situated in the tip of the roots that render the most desirable and suitable raw material to study the different stages of mitosis

Answer 2

Why use onion roots for viewing mitosis? The roots are easy to grow in large numbers. cells can be observed. The chromosomes can be stained to make them more easily observable.
Hope this helps!