Final answer:
The statement that Drosophila males have a frequency of crossing over about equal to females is false. While females undergo crossing over during meiosis, males do not. This difference is critical for understanding genetic recombination in fruit flies.
Step-by-step explanation:
In Drosophila, or fruit flies, the frequency of crossing over is not about equal between males and females. This is a false statement. In Drosophila melanogaster, females exhibit crossing over during meiosis, but males do not experience crossing over. This is due to differences in their meiotic processes. Consequently, crossing over and genetic recombination occur during oogenesis (egg development) in females, but not during spermatogenesis (sperm development) in males.
The observation of crossing over frequencies is a cornerstone in genetics, initially described by Thomas Hunt Morgan and his students, where they found that genetic recombination could be used to map the distance between genes on chromosomes. With a crossover frequency ranging between 0% and 50%, it indicates that the genes are located on the same chromosome and exhibit crossing over to varying degrees depending on their distance apart on the chromosome.