The amount of water needed daily by plants for photosynthesis, cell growth, and cell maintenance is very small, and yet plants require large volumes of water in order to live. It is estimated that over 90 percent of the water absorbed by plants is lost into the air. Most of the water loss is due to evaporation from the plant through the small openings in leaves called stomata. This loss of water vapor from plants is referred to as transpiration.
The data represent the average transpiration value for twenty plants under each of the six experimental conditions. The room conditions were a temperature of 22°C, fluorescent lighting, and low humidity.
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3) Which of the following statements best explains the results associated with condition 5?
A) When a fan was added to heat and additional light, the rate of transpiration was slowed to the rate associated with room conditions, because the fan cooled the plants.
B) Additional heat and light and air movement caused the plants to lose so much water that after five minutes they wilted, thereby closing their stomata and preventing further water loss.
C) Additional heat resulted in such severe water loss that it could not be counteracted by air movement caused by the fan, and the plants died.
D) After five minutes the rate of transpiration gradually increased, because moisture was being brought up the stem more rapidly.
4) Which of the following hypotheses about the effects of high humidity is supported by the graph?
A) Plants will grow faster.
B) Plant tissues will contain a smaller volume of water.
C) Plants will close their stomata.
D) Evaporation will proceed more slowly.
If this is an English class, it is obviously testing your reading + comprehension ability.
Sra
To answer question 3, we need to analyze the effects of the different experimental conditions on the rate of transpiration in plants.
Condition 5 involved the addition of a fan, heat, and additional light to the room conditions. The question asks for an explanation of the results associated with this condition.
Statement A suggests that the rate of transpiration was slowed to the rate associated with the room conditions because the fan cooled the plants. However, this contradicts the fact that additional heat and light were also introduced, which would increase transpiration. Therefore, statement A is not the best explanation.
Statement B suggests that the plants lost so much water due to the combination of additional heat, light, and air movement that they wilted and closed their stomata, preventing further water loss. This explanation aligns with the fact that plants lose water through transpiration, and excessive water loss can lead to wilting. Therefore, statement B is the best explanation.
Statement C suggests that the additional heat caused severe water loss that could not be counteracted by the fan, leading to plant death. However, there is no evidence to support plant death in the given information. Therefore, statement C is not the best explanation.
Statement D suggests that after five minutes, the rate of transpiration gradually increased because moisture was being brought up the stem more rapidly. However, there is no information provided about moisture being brought up the stem more rapidly, so statement D is not the best explanation.
Therefore, the best explanation for the results associated with condition 5 is statement B: additional heat, light, and air movement caused the plants to lose so much water that they wilted, closing their stomata and preventing further water loss.
To answer question 4, we need to analyze the graph and understand the effects of high humidity on transpiration.
The graph represents the average transpiration values for twenty plants under each of the six experimental conditions. Considering the room conditions, which had low humidity, we can compare it to the other conditions to understand the effects of high humidity.
Based on the given information, plants lose water through transpiration, with most of the water loss occurring due to evaporation from the leaves. High humidity refers to the presence of a large amount of water vapor in the air.
Hypotheses are educated guesses or explanations that can be tested. We need to determine which hypothesis about the effects of high humidity is supported by the graph.
Statement A suggests that plants will grow faster due to high humidity. However, the graph does not provide any information about plant growth rates. Therefore, statement A is not supported by the graph.
Statement B suggests that plant tissues will contain a smaller volume of water due to high humidity. This hypothesis is supported by the graph because higher humidity levels are associated with lower transpiration rates, indicating reduced water loss. Consequently, less water being lost through transpiration would result in plant tissues containing a smaller volume of water. Therefore, statement B is supported by the graph.
Statement C suggests that plants will close their stomata due to high humidity. The graph does not directly show the stomatal behavior of the plants, so we cannot determine whether or not the plants closed their stomata due to high humidity. Therefore, statement C is not supported by the graph.
Statement D suggests that evaporation will proceed more slowly due to high humidity. This hypothesis is supported by the graph because higher humidity levels are associated with lower transpiration rates, indicating that water loss through evaporation is indeed slower. Therefore, statement D is supported by the graph.
Therefore, the hypothesis about the effects of high humidity supported by the graph is statement B: plant tissues will contain a smaller volume of water. Additionally, statement D is also supported by the graph: evaporation will proceed more slowly.