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Listen to an Academic Talk Test #045
Listen to an Academic Talk
1. What is the main topic of the talk?
A) How invasive weeds spread
B) How plants compete using chemicals
C) The life cycle of the black walnut tree
D) The benefits of using natural herbicides
2. According to the professor, why is the chemical juglone significant?
A) It helps tomato plants grow faster.
B) It protects plants from insects.
C) It is produced by an invasive weed.
D) It is harmful to many other plants.
3. What would likely happen if a gardener plants an apple tree next to a black walnut tree?
A) The apple tree would grow very quickly.
B) The apple tree would probably not do well.
C) The black walnut tree would stop producing juglone.
D) The apple tree would absorb chemicals from the walnut tree.
4. Why does the professor mention agriculture?
A) To provide an example of a plant that uses allelopathy
B) To describe where black walnut trees are usually grown
C) To show a potential practical use for understanding allelopathy
D) To explain why some plants are considered invasive
Professor: We tend to think of plants as passive, but they often engage in a form of unseen warfare. This is done through a process called allelopathy. Allelopathy occurs when one plant produces and releases biochemicals that affect the growth, survival, and reproduction of other nearby plants.
A classic example is the black walnut tree. Its roots and decaying leaves release a chemical called juglone, which is toxic to many other plants. If you try to plant a tomato or an apple tree near a black walnut, it likely won't survive. This process effectively reduces competition for resources like water, sunlight, and nutrients.
Another example is spotted knapweed, an invasive plant that releases a chemical from its roots that can kill off native grasses, allowing the knapweed to take over large areas. Understanding these natural chemicals is more than just a curiosity; it has practical applications in agriculture for developing natural, plant-based herbicides.
A classic example is the black walnut tree. Its roots and decaying leaves release a chemical called juglone, which is toxic to many other plants. If you try to plant a tomato or an apple tree near a black walnut, it likely won't survive. This process effectively reduces competition for resources like water, sunlight, and nutrients.
Another example is spotted knapweed, an invasive plant that releases a chemical from its roots that can kill off native grasses, allowing the knapweed to take over large areas. Understanding these natural chemicals is more than just a curiosity; it has practical applications in agriculture for developing natural, plant-based herbicides.
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