对于“植物细胞的吸水和失水”这一探究实验,新教材提供紫色的洋葱作为实验材料。洋葱外表皮细胞含有紫色大液泡,不需染色即可直接观察到由于细胞吸水或失水而引起的液泡体积大小的变化。由于洋葱实际上只有外表皮呈现出紫色,对于中学生来说,难以取到只有单层细胞的观察材料。因为许多学生撕取的洋葱表皮厚薄不均、细胞重叠,只有少 For the exploratory experiment “Water Absorption and Water Loss in Plant Cells,” the new textbook provided purple onions as experimental materials. Onion epidermal cells contain large purple vacuoles, without staining can be directly observed due to cell water or water loss caused by changes in the size of vacuoles. Since the onion is actually only the outer skin showing purple, for high school students, it is difficult to get only monolayers of observation material. Because many students torn onion skin uneven thickness, overlapping cells, only less