Many flowering plants woo insect pollinators and gently direct them to their most fertile blossoms by changing the color of individual flowers from day to day. Through color cues, the plant signals to the insect that it would be better off visiting one flower on its bush than another. The particular hue tells the pollinator that the flower is full of far more pollen than are neighboring blooms. That nectar-rich flower also happens to be fertile and ready to disperse its pollen or to receive pollen the insect has picked up from another flower. Plants do not have to spend precious resources maintaining reservoirs of nectar in all their flowers. Thus, the color-coded communication system benefits both plants and insects.

   For example, on the lantana plant, a flower starts out on the first day as yellow, when it is rich with pollen and nectar. Influenced by an as-yet-unidentified environmental signal, the flower changes color by triggering the production of the pigment anthromyacin. It turns orange on the second day and red on the third. By the third day, it has no pollen to offer insects and is no longer fertile. On any given lantana bush, only 10 to 15 per cent of the blossoms are likely to be yellow and fertile. But in tests measuring the responsiveness of butterflies, it was discovered that the insects visited the yellow flowers at least 100 times more than would be expected from haphazard visitation. Experiments with paper flowers and painted flowers demonstrated that the butterflies were responding to color cues rather than, say, the scent of the nectar.

   In other types of plants, blossoms change from white to red, others from yellow to red, and so on. These color changes have been observed in some 74 families of plants.

The word “haphazard” is closest in meaning to which of the following?

Câu hỏi liên quan

• The word “vacations” in line 9 could be best replaced by ..............

• All of the following are true about the 1970 survey of Antarctica EXCEPT that it______.

• The author mentions all of the following as concerns of telecommuting EXCEPT ________.

ZUNIA12

• It may be concluded from this passage that ____________.

• A paragraph following the passage would most probably discuss_________.

• The word “emerged” means ...............

• According to the text, teaching requires a combination of many things EXCEPT ________.

• People thought Merlin was a dreamer because he ..............

• The word “partial" in the passage is closest in meaning to ..............

• The word “itself” in paragraph 3 refers to ________.

• Which of the following helps to create the Earth’s magnetic fields?

• The phrase "the wee hours" in paragraph 3 probably refers to the period of time _____.

• The word “prior” is CLOSET meaning to ...............

• The word “advantage” in the last paragraph most closely means ...........

• According to the passage, what causes the unique color and look of hummingbirds?

• Which sentence best expresses the main idea of the second paragraph?

• Which of the following best summarizes this passage?

• The word “elite” in the second paragraph is closest in meaning to___________.

• The word "others" in paragraph 3 refers to ................

• The word “them” in the second paragraph refers to ________.