(female) We all know that insects like to eat plants. But some plants are able to develop ways to protect themselves from insects. Today I'm gonna talk about some ways plants defend themselves.Now, some plants have physical features that prevent insects from landing on them. Like the passion plant, for example, its leaves have little spiky hairs all over them. They're like spikes, sticking out of the plant that are so numerous and dense that they prevent insects from landing on the leaves. Basically there're just no room for the insects to land. And since insects can't land on the leaves they can't eat them. So the little hairs serve as a physical feature that help protect passion plant from insects.All right! But other plants protect themselves using chemical defenses, like the potato plant. The potato plant is able to release a chemical throughout its leaf system whenever an insect attacks it, starts eating the leaf. So, say an insect starts eating a potato plant's leaf, that will cause the plant to react by releasing a chemical throughout its leaf system. The insect swallows this chemical as it eats. And this chemical discourages the insect from wanting to eat more of the plant. How? Well, the substance makes the insect feel full, like it's already had enough to eat. The insect no longer feels hungry so it stops eating the plant. So, b y emitting this chemical, the potato plant protects itself from insects."
Question
Using points from the lecture, explain how the passion plant and the potato plant defend themselves from insects.
Important Points
For this task, you should use the examples from the lecture to explain how plants defend themselves from insects. You should explain that plants can use both physical and chemical defenses. The passion plant uses a physical defense. This plant has spiky hairs on its leaves which prevent insects from landing on the plant and eating the leaves. The potato plant, on the other hand uses a chemical defense. This plant releases a chemical through its leaves when an insect eats it. The chemical makes the insect feel full, so it stops eating the plant.
Sample Response
According to the professor, there're two ways for plants to protect themselves from insects. The first one is physical defense; some plants like passion plant have physical features that prevent insects from landing on them. The passion plant has little spiky hairs that cover the whole leave. Since the spiky hairs are numerous and dense, the insects can hardly find room to stand on leaves, and therefore cannot eat leaves. Another one is chemical defense, like the one potato plant uses. When attacked by insects, the plant releases a chemical over its leaf system, which discourages the insect from further eating the plant by making the insect feel full, so the insect may think it's already had enough and stops eating. In this way the potato plant protects itself from insects. (127 words)
High-level Response: Listen to Track 31.
Rater’s Comments
The speaker gives a well-organized, clear response and is able to summarize all of the important information from the lecture. He jumps immediately into a summary of the examples, but he shows a clear connection between the two examples to the main concept. Consider his sentence: "On the other side, potato plants uses chemical features to prevent being eaten by insects." Though there are some grammatical errors in this sentence, he uses a transitional phrase "on the other side," and he stresses the word "chemical" to emphasize the contrast between the two examples. He does speak very quickly at times, but he shows that he is able to communicate without too many pauses and searching for words. He makes occasional pronunciation errors but has the ability to correct himself. For instance, he describes the chemical defenses that the potato plant uses "CO prevent being eaten." At first, "being eaten" is pronounced incorrectly, but he quickly corrects his pronunciation and continues with the response.
Mid-level Response: Listen to Track 32.
Rater’s Comments
This speaker is able to convey all of the important points from the lecture, but her response takes some effort to understand. She pauses frequently, searching for words. She clearly understood and is able to explain both examples, but her vocabulary is sometimes vague ("the potato plant has some, like, chemical things") or inaccurate. For instance, in the first point about the passion plant, she describes the spikes "which prevent him from the insect" instead of "which protect it from the insect." Her pronunciation is mostly easy to understand, but she does make a few mistakes that confuse her meaning. For example, while describing the chemical defenses of the potato plant, she says that "the insect doesn't feel hungry," but her pronunciation of "hungry" sounds more like "angry."