[单选题]
The diagram below shows a potometer whi
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A plant cutting was placed in the potometer as shown above. What changes would be observed after a few hours?
A. The water in the reservoir will increase.
B. The bubble will move right towards the direction of the beaker.
C. The bubble will move left towards the direction of the plant.
D. The water level in the beaker will rise.
参考答案:
C
本题详细解析:
A potometer is used to measure the rate of transpiration in a plant. When transpiration takes place, water loss occurs because water evaporates inside the leaves and then diffuses out of the leaves. The bubble in the capillary tube will move in the direction of the plant along with the water in the capillary tube which is being absorbed by the plant (Choice C).
Choice B is incorrect because the water and bubble are moving towards the plant, not away from it.
Choice A is incorrect because the water in the reservoir will stay at the same level. The reservoir contains a switch that is used to refill the capillary tube and push the bubble back to the start position. This is done at the end of the experiment to reset the apparatus for the next measurement.
Choice D is incorrect as the water level in the beaker will decrease as water enters the capillary tube and also because of evaporation from the beaker to the atmosphere.
