Reproduction by mitosis duplicates:

chromosomes
genes
dna
all of the above

SOS:

The answer is all of the above!

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.

i think that is new experiments yield untrustworthy data and should be carefully considered, because you don't know what will happen with the experiments.