Home
Listening
Listen to an Academic Talk Test #004
Listen to an Academic Talk
1. What is the main topic of the talk?
A) How insects find food sources
B) A method of communication between plants
C) The life cycle of the tomato plant
D) The effects of chemicals on plant growth
2. What does an attacked tomato plant do?
A) It changes the color of its leaves
B) It moves away from the threat
C) It releases chemicals into the air
D) It grows a thicker outer skin
3. What can be inferred about plants that receive the chemical signal?
A) They become more vulnerable to attack
B) They grow more quickly than other plants
C) They attract different kinds of insects
D) They are better prepared for a future threat
4. Why does the professor mention the whole plant community?
A) To show that the signal has a wide-ranging effect
B) To explain that only certain plants can communicate
C) To argue that this defense is not very effective
D) To give an example of competition among plants
Professor: Today we're discussing how plants defend themselves. They might seem passive, but they have some sophisticated strategies. One of the most fascinating is a form of communication. When some plants, like the tomato plant, are attacked by an insect—say, a caterpillar—they release specific chemical signals into the air. These are called volatile organic compounds.
Now, the interesting part is what happens next. Nearby tomato plants that are not yet under attack can detect these airborne signals. In response, they ramp up their own defenses. For instance, they might start producing chemicals that make their leaves less tasty or even toxic to insects. This happens *before* any caterpillars have reached them.
This is a kind of preemptive defense system. The warning signal from one plant gives the entire local plant community a head start in protecting itself, which can significantly improve their collective survival.
Now, the interesting part is what happens next. Nearby tomato plants that are not yet under attack can detect these airborne signals. In response, they ramp up their own defenses. For instance, they might start producing chemicals that make their leaves less tasty or even toxic to insects. This happens *before* any caterpillars have reached them.
This is a kind of preemptive defense system. The warning signal from one plant gives the entire local plant community a head start in protecting itself, which can significantly improve their collective survival.
Highlights
| ID: | #io7566918525 |
Tags
New TOEFL