What prevented the red onion cells from swelling up and bursting when they were placed in the distilled water?

It has a strong cell wall, which prevents the cells from swelling up and bursting. Hope this helps!

c) 50% there are four chromosomes. after crossing over, 2 of the four have been changed. that means any gamete has a 2 in 4 chance or 50% chance of receiving the mutated chromosome.

a and c are the answeres