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第1段
1 .<-NARRATOR:-> Listen to part of a lecture in a biology class.
请听生物课上的部分内容。
第2段
1 .<-FEMALE PROFESSOR:-> We all know that insects like to eat plants.
我们都知道昆虫喜欢吃植物。
2 .But some plants have been able to…to develop ways to protect themselves from insects.
但是有些植物进化出了抵抗昆虫侵害的方法。
3 .Today I'm gonna talk about some ways plants defend themselves.
今天我要讲一讲植物保护自己的一些方法。
4 .Now, some plants have physical features that prevent insects from landing on them, like the passion plant for example.
有些植物具有的体貌特征能够防止昆虫降落在它们身上。就像龙珠果一样，
5 .Its leaves have little spiky hairs all over them.
它的叶子上长满了尖刻的毛。
6 .They are like spikes, sticking out of the plant that are so numerous and dense that they prevent insects from landing on the leaves.
这些毛就像钉子一样突出在植物表面，数量繁多且生长茂，它们能够阻止昆虫飞落在叶子上。
7 .Basically there's just no room for the insect to land.
基本上根本没有地方可以让昆虫降落。
8 .And since insects can't land on the leaves they can't eat them.
既然昆虫无法落在叶子上，它自然无法吃了它们。
9 .So the little hairs serve as a physical feature that helps protect the passion plant from insects.
所以，这些毫毛就是保护龙珠果不受昆虫侵害的体貌特征。
10 .All right!
好了！
11 .But other plants protect themselves using chemical defenses, like the potato plant.
不过另一些植物会用化学手段来保护自己，比如马铃薯。
12 .The potato plant's able to release a chemical throughout its leaf system whenever an insect attacks it, starts eating leaf.
无论什么时候昆虫对它进行攻击，开始吃它的叶子，马铃薯都能通过叶系统释放出一种化学物质。
13 .So, say an insect starts eating a potato plant's leaf.
假设一只昆虫开始吃马铃薯的叶子，
14 .That will cause the plant to react by releasing a chemical throughout its leaf system.
这会使植物以通过叶系统释放化学物质的方式来做出反应。
15 .The insect swallows this chemical as it eats.
昆虫在食用叶子的过程中也吞下了这种化学物质。
16 .And this chemical discourages the insect from wanting to eat any more of the plant.
而这种化学物质会让昆虫不想再吃这种植物了。
17 .How?
为什么？
18 .Well, the substance makes the insect feel full, like it's already had enough to eat.
因为这种物质会让昆虫有饱腹感，
19 .The insect no longer feels hungry.
就像它已经吃得够多了一样。
20 .So it stops eating the plant.
昆虫觉得不饿了就会停止进食。
21 .So, by emitting this chemical, the potato plant protects itself from insects.
所以，通过释放化学物质，马铃薯能够从昆虫的侵害中保护自己。