Final answer:
Preliminary test curls in DNA extraction experiments provide information about the amount of DNA produced by different fruits and the reproducibility of the results.
Step-by-step explanation:
Preliminary test curls are used in DNA extraction experiments to analyze the amount of DNA produced by each sample. By comparing the results of different test curls, you can determine if there is a noticeable difference in the amount of DNA produced by different fruits. In addition, by repeating the test curls multiple times, you can examine whether your results are consistent and reproducible.