观察植物细胞质壁分离与复原的实验中，学生学会取用一薄层洋葱紫色外表皮是该实验成败与否的基础和关键。学生往往由于取用不当，看不到紫色液泡，或视野中仅个别细胞为紫色，更有几层细胞重叠的现象，直接影响实验效果。方法一：让学生先挑选洋葱鳞片叶色浅的部位，用刀片轻 In the experiment of observing the separation and restoration of the cytoplasm of plant cells, students learn to use a thin layer of onion purple outer epidermis as the basis and key to the success or failure of the experiment. Students often have improper access, do not see purple vacuoles, or only a few cells in the field of vision are purple, and there are several layers of cells overlapping, which directly affects the experimental results. Method one: Ask students to pick lighter parts of onion scales and lighter blades