2019年8月24日托福阅读真题+题目+答案：Honeybee Juvenile Hormone

2019年8月24日托福阅读真题+题目+答案：Honeybee Juvenile Hormone

The activities of honeybee hives are highly coordinated. Honeybees live in colonies made up of a single queen and up to 80,000 workers. The tasks of a worker usually change dramatically with age, a phenomenon known as age polyethism. A typical honeybee worker newly emerged as an adult, winged insect will live for approximately six weeks and during this time moves through an orderly progression of tasks: Young adults (4 to 12 days old) tend the queen and the pupae (pre-adult insects); middle-aged bees (13 to 20 days old) perform various tasks associated with nest maintenance and food storage; and the oldest bees (over 20 days of age) concentrate on foraging (searching for food) outside the nest. In general, young workers mostly stay inside the hive and tend to nursing and housekeeping, and older workers often leave the hive to forage. Keep in mind, however, that the actual changes in the duties performed by a worker usually involve only changes in the frequencies of particular types of behaviors with age, rather than the addition or loss of entire categories of behaviors. Also, the sequence is flexible, allowing duties to be reassigned if the hive’s needs change.

Age polyethism in worker honeybees is regulated by juvenile hormone (JH); levels of JH increase with age and mediate changes in work habits. These levels vary with age because of changes in 。。。。余下托福阅读真题省略！

1.According to the passage: the term “age polyethism" in honeybees refers to the phenomenon whereby

A the organization of the colony varies depending on the age of its queen

B the activities of a colony become more coordinated as the bees within it age

C workers of different ages perform the same task

D the age of a worker influences the type of duties the worker performs

2.According to paragraph 1, which of the following is true of young-adult workers?

A They often require the assistance of older workers to complete tasks.

B They tend to perform tasks that require them to remain within the hive.

C They spend more time working and less time resting than older workers do.

D They usually perform the tasks of locating and storing food.

3.The word ”sequence“ in the passage is closest in meaning to

A purpose

B order

C type

D behavior

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