jawaban blood pressure passage one toefl

(C) Plants cannot move water to high altitudes. (B) Cells in plant sterns do not pump water. What do the experiments mentioned in lines 5-7 prove? (A) Plant stems die when deprived of water. The word 'demonstrated' in line 6 is closest in meaning to (A) ignored (B) showed (C) disguised (D) distinguished 4. The passage answers which of the following questions ? (A) What is the effect of atmospheric pressure on foliage? (B) When do dead cells harm plant growth? (C) How does water get to the tops of trees? (D) Why is root pressure weak? 3. How many theories does the author mention? (A) One B) Two (C) Three (D) Four 2. This cohesive strength permits columns of water to be pulled to great heights without being broken. When water is confined in tubes of 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. The same forces that create surface tension in any sample of water are responsible for the maintenance of these unbroken columns (20) of water. 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. As water is lost from the surface of the leaves, a negative pressure or tension is created. The pull on a rising column of water in a (15) plant results from the evaporation of water at the top of the plant. How does it get there? According to the currently accepted cohesion-tension theory, water is pulled there. 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.

But root pressure is not nearly great enough to push water to the tops of tall (10) trees, Furthermore, the conifers, which are among the tallest trees have unusually low root pressures. 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. Some botanists (5) hypothesized that the living cells of plants acted as pumps, but many experiments demonstrated that the stems of plants in which all the cells are killed can still move water to appreciable heights. Until the end of the nineteenth century, the Line movement of water's in trees and other tall plants was a mystery. But plants can move water much higher, the sequoia tree can pump water to its very top, more than 100 meters above the ground. TOEFL READING COMPREHENSION TEST 41 Questions 1-13 Atmospheric pressure can support a column of water up to 10 meters high.

Jawaban blood pressure passage one toefl