Read the following passage and choose the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions:

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.

Question: Which of the following describes the sequence of color changes that lantana blossom undergo?         

A.

A. Red to purple                

B.

B. Yellow to orange to red         

C.

C. Red to yellow to white            

D.

D. White to red  

Đáp án và lời giải
Đáp án:B
Lời giải:

Đáp án B

Điều nào sau đây mô tả trình tự của thay đổi màu sắc mà hoa lantana trải qua?

A. đỏ đến tím             

B. vàng đến cam đến đỏ

C. đỏ sang vàng sang trắng                

D. Trắng đến đỏ

Thông tin ở đoạn 2 của bài: 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. => Ngày đầu tiên màu vàng, ngày thứ 2 màu cam, ngày thứ 3 màu đỏ.     

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