Ap Biology Lab 9: Transpiration Essay
657 WordsAug 14th, 20123 Pages
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,…show more content…
The room temperature had little or no effect on the water potential. The mist increased the water potential of the air causing less transpiration to occur from the leaves.
5. What is the advantage to a plant of closed stomata when water is in short supply? What are the disadvantages? When water is in short supply a plant with a closed stomata has the luck that no matter what environmental situation it’s in (extreme heat, windy conditions, etc.) it will be able to control the water that it needs from escaping regardless of the environment it’s placed in.
6. Describe several adaptations that enable plants to reduce water loss from their leaves. Include both structural and physiological adaptations.
Plants that are adapted to drier climates are called xerophytes (an example if these types of plants are cactus). Some of these plants have adapted small, thick leaves with a reduced surface area. They may also have a thickened cuticle to protect themselves from the environment. The stomata may be sunken into pits. Some xerophytes shed their leaves during the driest seasons and others can store water such as cacti. CAM plants uptake CO2 at night and change it into crassulacean acid that can be broken down during the day for sugars. These plants can close their stomata during the day.
7. Why did you need to calculate the % of water loss each day instead of graphing the total amount of water lost each day? We need to calculate the percentage of water
Biology Osmosis Lab Report Essay
1890 WordsFeb 13th, 20138 Pages
Osmosis Lab Report
First Lab Report
February 20, 2013
The major objective of the experiment was to test the effect of the concentration gradient on the diffusion rate. It was hypothesized that the greater the stronger the concentration gradient, the faster the rate of diffusion would be. To test this, dialysis tubes were submerged in different concentration fructose solutions. We weighed the tubes at specific time intervals to measure the rate of diffusion of water in each different solution. The results illustrated that increased concentration gradient increases the rate of diffusion of water in the tubes. We concluded that as concentration of the…show more content…
The following hypothesis was made in regard to effect of the concentration gradient on the rate of diffusion: The higher the concentration gradient, the faster the rate of diffusion.
Materials & Methods
There were several steps completed to prepare for the experiment. Three dialysis tubes were filled with approximately the same volume of distilled water and then were tied shut. The initial mass (in grams) of the tubes was taken using a triple beam scale. I then filled three 500 mL beakers with 400 mL of water each and dissolved different masses of solute (table sugar) in each beaker in order to make 5%, 10%, and 20% solutions. The beakers were labeled accordingly, and then 20 g, 40 g, and 80 g (respectively) of table sugar was weighed out using a digital scale and placed into the corresponding beakers. The sugar was stirred in using a stirring rod until all of the solute was completely dissolved. One dialysis tube was submerged in each beaker. Osmosis was allowed to occur for 5 minutes and then all of the tubes were removed from the water. The tubes were dried off and measured on the triple beam scale. The mass was taken and recorded for all three tubes. I then placed the tubes back into their respective solutions. The process was repeated four times for each tube in 5 minute increments, and then the materials were disposed of. The rate of diffusion of water in each solution was