# Ap Biology Lab 9: Transpiration

Topics: Photosynthesis, Plant physiology, Leaf Pages: 2 (665 words) Published: August 29, 2012
AP Biology Lab 9 Analysis
1. For this experiment, what were the independent variable and the dependent variable? What were the constants? The independent variable of this experiment are the environmental factors that you are testing on the rate of transpiration, so our independent variables would be bright light, fan, dark, and misted. The dependent variable is the rate of transportation because this depends on whatever environmental factor the plant is placed. The constants were things like the type of plant we used, the room temperature, the type of scale we used and how far the fan/light was placed from the plant. 2. Calculate the average rate of water loss per day for each of the treatments(Humidity, Light, Fan, Dark, Room, or control). Environmental Factor | Average Rate of Water Loss Per Day| Bright Light | 21.63|

Fan| 10.8 |
Dark| 5.03|
Misted | 5.33|

3. Explain why each of the conditions causes an increase or decrease in transportation compared to the control.
A good way to imagine transportation is to think about a wet towel drying and how long it would take to dry off in these different environmental factors. The environmental factor that had the highest average rate of water loss per day was the plant placed by the bright light. The heat from the light sped up transpiration. The fan also had a decent high amount of water loss per day because the fan provided the plant with air currents that also facilitated in transpiration. In the mist there was little transpiration lost because the saturated wet atmosphere that it produced decreased the amount of water lost. However, in the dark turned out to have the lowest average water loss per day because transpiration requires some type of driving source (light, wind, etc) for water to travel from the roots of the plant to the stomata of the leafs. 4. How did each condition affect the gradient of water potential from the stem to the leaf in the experimental plant?...