TOEFL Reading練習 #002 — The Grasshopper That Becomes a Locust(日本語解説)

1. A. the cause that starts something
2. B. the result that follows something
3. C. a warning sign of danger
4. D. a small physical object

1. A. the touching between the grasshoppers' legs
2. B. the sharp rise in the level of serotonin
3. C. the switch inside the insect's body
4. D. the phase change itself

1. A. the sudden rise in the level of serotonin inside the insect
2. B. the process of forming a large flying swarm that can travel far
3. C. any change in an insect's body size as it grows older
4. D. a shift from a shy, solitary way of living to a bold, group-based way of living, triggered by repeated touching

1. A. It drops slowly over several days
2. B. It stays exactly the same
3. C. It rises sharply within a few hours
4. D. It rises only after several weeks

1. A. Adult locusts always live and travel completely alone
2. B. A swarm can hold more than forty million insects in one square kilometer
3. C. A swarm that size can eat as much food in a day as thirty-five thousand people
4. D. Nearly every locust begins life as an ordinary, solitary grasshopper

1. A. The rise in serotonin causes the grasshoppers' legs to keep touching each other.
2. B. The chemical level inside the insect's body changes over time.
3. C. Only when insects touch each other more than a hundred times does the serotonin level rise.
4. D. Because the touching keeps happening over and over, the insect's serotonin level rises quickly, within just a few hours.

1. A. It would develop a darker color and longer wings without ever being touched
2. B. It would likely stay in the shy, solitary phase, since its legs are never touched repeatedly
3. C. It would eventually form a swarm on its own, because all grasshoppers eventually become locusts
4. D. Its serotonin level would rise gradually over many years even without touching

1. A. warn readers not to travel to East Africa
2. B. explain in more detail how serotonin works inside the insect's body
3. C. give a real, large-scale example of how the phase-change process described earlier can play out
4. D. compare desert locusts with other kinds of grasshoppers found in Africa

1. A. It presents a real event in which the mechanism described earlier actually happened on a large scale
2. B. It argues that the explanation given earlier is incorrect
3. C. It repeats the description of serotonin's role in more detail
4. D. It explains the relationship between two completely different paragraphs earlier in the passage

1. A. Square A
2. B. Square B
3. C. Square C
4. D. Square D

Ordinary, solitary grasshoppers can transform into a destructive, swarming locust through a process triggered by repeated physical contact.

1. A. A locust swarm covering one square kilometer can eat as much food in a day as thirty-five thousand people.
2. B. Repeated touching between grasshoppers' legs causes a sharp rise in serotonin, which triggers a shift called a phase change.
3. C. In the gregarious phase, the insects gather into growing marching bands and eventually form flying swarms.
4. D. In 2020, this process caused a severe locust outbreak in East Africa that threatened food for millions of people.
5. E. Locust swarms always travel over a hundred kilometers a day, no matter the weather conditions.
6. F. Scientists first discovered serotonin's role in locust behavior through laboratory experiments in the 1990s.