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.
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 movements caused the plants to loose 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
Without a description of the six experimental conditions, and the "graph" which is mentioned, it is not possible to help you with that question.
To answer these questions, we need to analyze the information provided and understand the concepts of transpiration and its factors.
Transpiration is the process by which water is lost from plants through evaporation from the stomata in their leaves. Stomata are small openings that allow gases to enter and exit the plant, but they also lead to water loss.
Now let's analyze each question:
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 movements 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.
To determine the correct answer, we need to consider the effects of heat, light, and air movement on transpiration. Heat and light usually increase transpiration, while air movement can have both cooling and drying effects on the plants.
Based on the given information, it is mentioned that the room conditions had low humidity. Humidity refers to the amount of moisture present in the air. In this case, the addition of a fan could potentially increase air movement and help reduce the rate of transpiration because it cools the plants. Therefore, the best explanation for the results associated with condition 5 would be option 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.
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
To determine the supported hypothesis about high humidity, we need to look at the graph provided (which is not mentioned in the question). However, based on the given information that room conditions had low humidity, we can assume that high humidity would have the opposite effect on transpiration. When humidity is high, the air is already saturated with moisture, making it more difficult for water to evaporate from the leaves' stomata. Therefore, the correct answer would be d) Evaporation will proceed more slowly.
In summary:
3) The best explanation for the results associated with condition 5 is 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.
4) The supported hypothesis about the effects of high humidity is d) Evaporation will proceed more slowly.