Read the following passage and choose the correct answer for each question.
Atmospheric pressure can support a column of water up to 10 meters high. But plants can move water much higher, the sequoia tree can pump water to its very top, more than 100 meters above the ground. Until the end of the nineteenth century, the movement of water in trees and other tall plants was a mystery. Some botanists hypothesized that the living cells of plants in which all the cells are killed can still move water to appreciable heights. Other explanations for the movement of water in plants have been based on root pressure, a push on the water from the roots at the bottom of the plant. But root pressure is not nearly great enough to push water to the tops of tall trees. Furthermore, the conifers, which are among the tallest trees, have unusually low root pressures.
If water is not pumped to the top of a tall tree, and if it is not pushed to the top of a tall tree, then we may ask: “How does it get there?” According to the currently accepted cohesion-tension theory, water is pulled there. The pull on a rising column of water in a plant results from the evaporation of water at the top of the plant. As water is lost from the surface of the leaves, a negative pressure, or tension, is created. The evaporated water is replaced by water moving from inside the plant in unbroken columns that extend from the top of a plant to its roots. The same forces that create surface tension in any sample of water are responsible for the maintenance of these unbroken columns of water. When water is confined in tubes of a very small bore, the forces of cohesion (the attraction between water molecules) are so great that the strength of a column of water compares with the strength of a steel wire of the same diameter. This cohesive strength permits columns of water to be pulled to great heights without being broken.
What do the experiments mentioned in lines 4-6 prove?
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Lời giải:
Báo saiGiải thích: Some botanists hypothesized that the living cells of plants in which all the cells are killed can still move water to appreciable heights. Other explanations for the movement of water in plants have been based on root pressure, a push on the water from the roots at the bottom of the plant. But root pressure is not nearly great enough to push water to the tops of tall trees. Furthermore, the conifers, which are among the tallest trees, have unusually low root pressures. => Một số nhà thực vật học đưa ra giả thuyết rằng các tế bào sống của thực vật trong đó tất cả các tế bào bị giết vẫn có thể di chuyển nước lên độ cao đáng kể. Các giải thích khác cho sự chuyển động của nước trong cây dựa trên áp lực của rễ, một lực đẩy nước từ rễ ở dưới cùng của cây. Nhưng áp lực rễ gần như không đủ lớn để đẩy nước lên ngọn cây cao. Hơn nữa, các cây lá kim, một trong những cây cao nhất, có áp lực rễ thấp bất thường.
Tạm dịch: Những thí nghiệm nêu ở dòng 4-6 chứng minh điều gì?
A. Thân cây chết khi thiếu nước.
B. Tế bào trong thân cây không bơm nước.
C. Thực vật không thể di chuyển nước lên độ cao.
D. Tế bào thực vật điều hòa áp suất bên trong thân cây.