Answer
Crossing over mixes DNA from two parents on one chromosome and unequal crossing over can eliminate DNA, which is seen to have occurred in Fig. 24.18.
Work Step by Step
Review Ch. 13 and the process of crossing over. Then look up unequal crossing over and how it can change the contents of a chromosome. If there was no crossover, the hybrid chromosomes would only contain DNA from one parent or the other.
