2016年1月12日托福阅读真题解析.doc

3 年1月 12 日托福阅读真题解析第一篇植物开花与日照的关系【机经回忆】什么因素影响花期植物通过感受不同光照事件长短,决定播种,科学家通过对叶子遮光处理,分为三种: 不受光影响, 长日照和短日照, 检测植物的信号。但是最后还是没有收获, 但是日照长短对植物的影响是明显的【重点词汇解析】 sunlight 日光 long-day 长日照 short day 短日照 plant 植物 seed 种子 signal 信号 obvious 明显的【机经解析】光照长短对植物生长的影响 Light duration or photoperiod refers to the amount of time that a plant is exposed to sunlight. When the concept of photoperiod was first recognized it was thought that the length of periods of light triggered flowering. The various categories of respons e were named according to the light length (., short-day and long-day). It was then discovered that it is not the length of the light period but length of uninterrupted dark periods that is critical to floral development. The ability of many plants to flower is controlled by photoperiod. Plants can be classified into three categories, depending upon their flowering response to the duration of darkness. These are short-day, long-day, or day-neutral plants. Short-day, (long nights) plants form their flowers only when the day length is less than about 12 hours in duration. Short-day plants include many spring and fall flowering plants such as chrysanthemum and poinsettia. Long-day, (short nights) plants form flowers only when day lengths exceed 12 hours. They include almost all of the summer-flowering plants, as well as many vegetables including beet, radish, lettuce, spinach, and potato. D