Although all four phenotypes are generated by simulation the numbers are different than those generated by simulation How can this best be explained?

Although all four phenotypes are generated by simulation the numbers are different than those generated by simulation How can this best be explained? Correct Answer The students assumed that crossing over of linked genes occurred during cell division.

C. If genes are on the same chromosome, they do not assort independently, but they can exchange (cross over) with like genes on the homologous chromosome. Generally, the farther the genes are separated on the chromosome, the more often they are likely to cross over (because there are more places between the genes for the chromosome to break and recombine). As in this question, where the ratio of phenotypes is about 7:3:3:7, crossing over generates phenotypes among offspring in ratios that may not look like typical crosses (for example, 9:3:3:1 or 1:1:1:1). Watch for these kinds of questions: When the phenotypes of offspring are produced in numbers skewed toward the phenotypes of certain parents, suspect linkage with crossing over. When skewing is dramatic, as in the previous question, suspect linkage with no crossing over. Although this question does not request it, the crossing over frequency in simulation 3 is 30%, as the following figure illustrates.