Photosynthesis Lab Report
Determining the Effect of Light Intensity on Photosynthesis
Avalon Pernell, et al
Abstract: The purpose of this lab was to determine how light affected photosynthesis, specifically the production of O2 bubbles. It was predicted that when the light was more intense the O2 bubble production will be high. Conversely, when the light was less intense the O2 bubble production will be lower. Basically the plant that is closer to the light will produce more bubbles than the plant that is placed farther away from the light source. In this lab the independent variable is the light intensity (distance from light source) and the dependent variable is oxygen output (number of bubbles). Since the distance was changed in the lab the control was the plant placed 0.0m away from the light source. After, evenly cutting 10 evergreen sprigs and placing them at the bottom of each test tube, each tray of …show more content…
test tubes were placed at their set distances from the light source. Once twenty minutes had past each lab group proceeded to count the amount of bubbles in each test tube and calculate the average number of bubbles at each distance. In evaluating the results it was revealed that the when the plant’s distance from the light source surpasses 1.0m, the average number of bubbles contained in the test tubes decreases. One of the problems that occurred within this lab was the production of large bubbles which could indicate a larger accumulation of oxygen. This could be resolved by using a gas syringe to determine the exact amount of oxygen contained in the bubbles. Introduction Photosynthesis is a process found in bacteria, plants, protists etc. Plants absorb the color: blue and red and reflect the color green. There are two phases of photosynthesis all of which occur and in the chloroplast. In phase one the light dependent reactions occur and light energy is absorbed and turned into chemical energy while in phase two, two ATP and NADPH are used to create glucose which when produced can be joined to simple sugars to form larger molecules. Light reactions occur in the thylakoids. Energy produced by the light reaction fuels the Calvin Cycle, and the ATP produced as a result of photosynthesis is used to fuel other processes like cellular respiration. The purpose of this lab was to determine how the intensity of light affected photosynthesis, specifically the production of O2 bubbles. It was hypothesized that when the light was more intense the O2 bubble production will be high. On the other hand, when the light was less intense the O2 bubble production would be lower. Therefore plants would produce more bubbles when placed near the light source and less when placed farther away.
Method
In this lab the independent variable is the light intensity (distance from light source) and the dependent variable is oxygen output (number of bubbles).
Since the distance was changed in the lab the control was the plant placed 0.0m away from the light source. The steps used to complete this lab were as follows: begin by filling test tubes with a water/sodium bicarbonate mixture using the pipette and evenly cutting 10 evergreen sprigs. Once this is completed place one evergreen sprig at the bottom of each test tube. Place each test tube rack at their set distance from the light source and wait for 20 minutes. After the 20 minutes has expired proceed to count the bubbles in each test tube and record each group’s data in the data table. Calculate the average number of bubbles and graph accordingly.
Results
At 0.0m the average number of bubbles equaled ≈12. At 0.5m the average number of bubbles was ≈4 with the erroneous data, and ≈13 when using the correct data given by the instructor. The average number of bubbles continued to decrease to ≈12 at 1.0m, ≈9 at 1.5m, and 9 at
2.0m.
Distance from light 0.0m 0.5m 1.0m 1.5m 2.0m
Tube 1 11 5* 10 10 9
Tube 2 12 4* 13 7 9
Average # of Bubbles ≈12 ≈4 ≈12 ≈9 9
*The instructor checked this group’s test tubes and found that tube 1 contained 12 bubbles and that tube 2 contained 13.
Discussion When analyzing the results of the lab it was determined that there was a correlation between light intensity and O2 bubble production. Generally speaking the closer the plant is to the light source the larger the average number of bubbles is. At 0.0m the average number of bubbles was 12 and at 2.0 the average number of bubbles was 9. Once the distance of the plant surpasses 1.0m the average number of bubbles drops below 10. Many people involved in this lab miscounted bubbles because they had no prior knowledge of how to spot and count bubbles. Another problem occurred when water was placed in the test tubes. Instead of using the pipette, the person tried to directly pour the water into the test tube from the flask. Lastly larger bubbles can form on plant leaves and indicate a large accumulation of oxygen. A few solutions to the problems listed above are to explain and identify bubbles at the beginning of the lab. Also to have lab groups check each other’s bubble counts for mistakes. This problem can be resolved by using a gas syringe to measure the exact amount of oxygen contained within the bubble.
Avalon Pernell, et al
Abstract: The purpose of this lab was to determine how light affected photosynthesis, specifically the production of O2 bubbles. It was predicted that when the light was more intense the O2 bubble production will be high. Conversely, when the light was less intense the O2 bubble production will be lower. Basically the plant that is closer to the light will produce more bubbles than the plant that is placed farther away from the light source. In this lab the independent variable is the light intensity (distance from light source) and the dependent variable is oxygen output (number of bubbles). Since the distance was changed in the lab the control was the plant placed 0.0m away from the light source. After, evenly cutting 10 evergreen sprigs and placing them at the bottom of each test tube, each tray of …show more content…
test tubes were placed at their set distances from the light source. Once twenty minutes had past each lab group proceeded to count the amount of bubbles in each test tube and calculate the average number of bubbles at each distance. In evaluating the results it was revealed that the when the plant’s distance from the light source surpasses 1.0m, the average number of bubbles contained in the test tubes decreases. One of the problems that occurred within this lab was the production of large bubbles which could indicate a larger accumulation of oxygen. This could be resolved by using a gas syringe to determine the exact amount of oxygen contained in the bubbles. Introduction Photosynthesis is a process found in bacteria, plants, protists etc. Plants absorb the color: blue and red and reflect the color green. There are two phases of photosynthesis all of which occur and in the chloroplast. In phase one the light dependent reactions occur and light energy is absorbed and turned into chemical energy while in phase two, two ATP and NADPH are used to create glucose which when produced can be joined to simple sugars to form larger molecules. Light reactions occur in the thylakoids. Energy produced by the light reaction fuels the Calvin Cycle, and the ATP produced as a result of photosynthesis is used to fuel other processes like cellular respiration. The purpose of this lab was to determine how the intensity of light affected photosynthesis, specifically the production of O2 bubbles. It was hypothesized that when the light was more intense the O2 bubble production will be high. On the other hand, when the light was less intense the O2 bubble production would be lower. Therefore plants would produce more bubbles when placed near the light source and less when placed farther away.
Method
In this lab the independent variable is the light intensity (distance from light source) and the dependent variable is oxygen output (number of bubbles).
Since the distance was changed in the lab the control was the plant placed 0.0m away from the light source. The steps used to complete this lab were as follows: begin by filling test tubes with a water/sodium bicarbonate mixture using the pipette and evenly cutting 10 evergreen sprigs. Once this is completed place one evergreen sprig at the bottom of each test tube. Place each test tube rack at their set distance from the light source and wait for 20 minutes. After the 20 minutes has expired proceed to count the bubbles in each test tube and record each group’s data in the data table. Calculate the average number of bubbles and graph accordingly.
Results
At 0.0m the average number of bubbles equaled ≈12. At 0.5m the average number of bubbles was ≈4 with the erroneous data, and ≈13 when using the correct data given by the instructor. The average number of bubbles continued to decrease to ≈12 at 1.0m, ≈9 at 1.5m, and 9 at
2.0m.
Distance from light 0.0m 0.5m 1.0m 1.5m 2.0m
Tube 1 11 5* 10 10 9
Tube 2 12 4* 13 7 9
Average # of Bubbles ≈12 ≈4 ≈12 ≈9 9
*The instructor checked this group’s test tubes and found that tube 1 contained 12 bubbles and that tube 2 contained 13.
Discussion When analyzing the results of the lab it was determined that there was a correlation between light intensity and O2 bubble production. Generally speaking the closer the plant is to the light source the larger the average number of bubbles is. At 0.0m the average number of bubbles was 12 and at 2.0 the average number of bubbles was 9. Once the distance of the plant surpasses 1.0m the average number of bubbles drops below 10. Many people involved in this lab miscounted bubbles because they had no prior knowledge of how to spot and count bubbles. Another problem occurred when water was placed in the test tubes. Instead of using the pipette, the person tried to directly pour the water into the test tube from the flask. Lastly larger bubbles can form on plant leaves and indicate a large accumulation of oxygen. A few solutions to the problems listed above are to explain and identify bubbles at the beginning of the lab. Also to have lab groups check each other’s bubble counts for mistakes. This problem can be resolved by using a gas syringe to measure the exact amount of oxygen contained within the bubble.