Lê Quỳnh  Anh

Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions from 43 to 50.

Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs are fused in a single structure called the column. The column is designed so that a single pollination will fertilize hundreds or thousands, and in some cases millions, of seeds, so microscopic and light they are easily carried by the breeze. Surrounding the column are three sepals and three petals, sometimes easily recognizable as such, often distorted into gorgeous, weird, but always functional shapes. The most noticeable of the petals is called the labellum, or lip. It is often dramatically marked as an unmistakable landing strip to attract the specific insect the orchid has chosen as its pollinator.

To lure their pollinators from afar, orchids use appropriately intriguing shapes, colors, and scents. At least 50 different aromatic compounds have been analyzed in the orchid family, each blended to attract one, or at most a few, species of insects or birds. Some orchids even change their scents to interest different insects at different times.

Once the right insect has been attracted, some orchids present all sorts of one-way obstacle courses to make sure it does not leave until pollen has been accurately placed or removed. By such ingenious adaptations to specific pollinators, orchids have avoided the hazards of rampant crossbreeding in the wild, assuring the survival of species as discrete identities. At the same time they have made themselves irresistible to collectors.

How many orchid seeds are typically pollinated at one time?

A. 200

B. 2,000

C. 20,000

D. 200,000

Dương Hoàn Anh
9 tháng 4 2019 lúc 3:22

Đáp án D

Thông tin: The column is designed so that a single pollination will fertilize hundreds or thousands, and in some cases millions, of seeds

Dịch nghĩa: Trụ nhụy được thiết kế để cho một hạt phấn duy nhất sẽ thụ tinh cho hàng trăm hoặc hàng ngàn, và trong một số trường hợp hàng triệu, hạt giống

Từ thông tin trên, phương án D. 200,000 là phương án chính xác nhất. Các phương án còn lại đưa ra con số quá nhỏ.

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