自交与自由交配一直是学生学习的难点,如何让学生能够准确理解自交与自由交配的区别,遇到相关题目能够迅速准确的解决,本文通过一道典例的多种解法,以期帮助学生突破难点,走出误区.典例已知果蝇的灰身和黑身是一对相对性状,基因位于常染色体上,将纯种的灰身果蝇和黑身果蝇杂交,F1全为灰身;(1)若让F1自由交配产生F2,将F2中的灰身果蝇取出,让 How to make students understand the difference between selfing and freedom mate correctly and how to solve the problems quickly and exactly. This article tries to help students to break through the method of multiple solutions of a typical example Difficulties out of the wrongdoing.Examples of known Drosophila gray body and black body is a pair of relative traits, the gene is located on autosomes, purebred drosophila fruit fly and black flies, F1 all gray; (1) If F2 is allowed to mate freely to produce F2, the gray flies in F2 are removed and let