Part VII. Practice
PASSAGE 1
1. What is the professor mainly discussing?
A. Insects that feed on plants
B. Animals that feed on insects
C. Plants that use insects to survive
D. Insects that are attractive to plants
2. Why is the professor discussing this topic?
A. He is lecturing about something that the students will see the next day
B. He is preparing the students for an exam that is tomorrow.
C. He is explaining something that the students have just seen.
D. He is discussing something that the students will be required to read.
3. What does an insectivorous plant get from an insect?
A. All of its nutrients
B. Chlorophyll
C. Nitrogen
D. Digestive liquid
4. According to the lecturer, how widespread are insectivorous plants?
A. There are hundreds of varieties in the world
B. They exist in 500 countries in the world.
C. They exist only in North America.
D. There are five different types throughout the world.
5. What is stated in the lecture about the Venus flytrap?
A. It is the largest insectivorous plant.
B. It is found only in South America.
C. It has moveable parts
D. It has only one trap leaf.
6. What is stated in the lecture about the sensory bristles? Click on 2 answers
A. They are divided into two parts.
B. There are three of them.
C. They are on the outside of the leaf.
D. They cause the trap leaf to close
LISTENING SCRIPT
Listen to a lecture in a botany class.
Today, we're going to be talking about insectivorous plants. As you know, we have a field trip tomorrow. We'll be going to the botanical gardens, and we're going to be seeing some insectivorous plants there.
Do you understand what insectivorous plants are? Insectivorous plants are plants that trap and assimilate insects in order to sustain life. You may understand the meaning of insectivore from related words such as carnivore or herbivore: a carnivore eats meat, and an herbivore eats plants, while an insectivore devours insects. But—unlike carnivores and herbivores, which are animals—the insectivores that we're going to discuss today are plants.
All insectivorous plants contain chlorophyll and have roots, so they don't get all of their nutrients from the insects they take in. Insectivorous plants tend to live in soil that lacks enough nitrogen for them to exist, so they consume their insect victims in order to get the nitrogen they need. There're many types of insectivorous plants in the world—there're perhaps 500 known species of insectivorous plants worldwide. Of these many types of insectivorous plants, we're going to look at one of the better known ones in depth.
The insectivorous plant that we're going to discuss in detail is the Venus flytrap, which is native to North America. Now look at the drawing of the Venus flytrap on the screen. The Venus flytrap catches insects by suddenly snapping the ends of one of its trap leaves around an insect.
You can see in the diagram that a Venus flytrap has a number of trap leaves and that each trap leaf is divided into two parts. Inside the two parts of the trap leaf are three sensory bristles, sensory bristles which resemble tiny hairs. When an insect touches the bristles inside a trap leaf, the two surfaces of the leaf shut instantaneously, and the insect's trapped inside the parts of the leaf. The Venus flytrap then discharges a digestive liquid into the leaf in order to assimilate the insect and obtain the nitrogen the plant needs in order to survive.
That's all for today on the Venus flytrap. I hope that from our discussion of the Venus flytrap you've developed a clearer understanding of how this and other insectivorous plants function. You'll need it for the trip tomorrow.