# Essay on Photosynthesis Lab

An Experiment to Test the Effect of Temperature on the Rate of Photosynthesis in Green Algae Background Photosynthesis is an amazing process where plants are able to create their own food as well as oxygen using sunlight, carbon dioxide (co2), and water. The part of the plant responsible for photosynthesis is the enzymes in the chlorophyll (structures that carry out photosynthesis located in leaves). Photosynthesis is the process of creating glucose. Water + Carbon Dioxide + Sunlight = Glucose + Oxygen. There are three main factors that can influence the rate of photosynthesis– temperature, carbon dioxide levels and light.

If one of these factors is not present or in insufficient quantities, photosynthesis cannot occur. This experiment will test the effect of different temperatures on the rate of photosynthesis of green algae. Photosynthesis optimal temperature in between 10C and 20C. Photosynthesis is a remarkable process that holds the balance of our Earth. The equation for photosynthesis is shown below: 6H20 + 6C02 ———-> C6H1206+ 602 Aim The aim of this experiment is to test the rate of photosynthesis in different temperatures by measuring the percentage of absorbed light in a colorimeter.

Research Question What is the effect of varying temperatures on the rate of photosynthesis in green algae? Research Hypothesis If green algae is exposed to differing external increasing temperatures, then the rate of photosynthesis will increase. Independent Variable The independent variable in the experiment is the differing temperature environments around the algae (5, 25, 45, 55) Dependent Variable The dependent variable is the rate of photosynthesis of the algae (the absorbance of light in nanometers) Rate of photosynthesis = absorbance of light

Constant Amount of chemical indicator solution 4mL Ensure a stable environment Amount of algae beads Control the rate of photosynthesis of a certain number of beads (more or less in a trial could alter the rate) Light intensity (lamps to mimic sunlight) Ensure the same sunlight conditions reach the algae Amount of time in between trials Ensure there is an equal and constant amount of time for photosynthesis to occur Materials Algae Chemical indicator solution Colorimeter Pipet Test tube Hot plate Light Ice Kim paper Cuvette Box

Beaker Test tube holder Ice Procedures Measure out 6 mL of the chemical indicator solution and put it in a test tube along with 6 beads of algae. Make 4 of these. Set up 4 different temperature zones as follows. Put water in each beaker. Cold temp: Place ice in a beaker to mimic cold conditions— 5 C Room temp: Place test tubes in the test tube rack– 25 C Mild temp: Place test tube in beaker on hot plate heated to– 45 C Hot temp: Place test tube in beaker on hot plate heated to– 55 C Place each test tube in a different temperature zone.

Set up lamps in front of each temperature zone to mimic light intensity Calibrate colorimeter to 1. 0 nanometers. Set a running timer with alarms at 20 mins, 40 mins, and 60 mins. Place each test tube in its designated temperature zone. Leave them there until the first alarm at 20 mins. Pull the test tube out of the water/ice and use a pipet to take out 4 mL of the chemical indicator solution and place it in a cuvette box then seal with lid. Wipe the box off with the Kim paper to eliminate any dirt or fingerprints that could interfere with the readings.

Place the cuvette box in the colorimeter. Allow the colorimeter to measure the absorbed light and then take the cuvette. Pipet all the solution from the cuvette box back into the same test tube for further tests at later times of 40 and 60 mins. Repeat steps 8-11 for each time– 20 mins, 40 mins, and 60 mins Record all data in a data table and make observations Mean Rates of Photosynthesis In Different Temperature Environments Cold 5C Room Temp 25C Mild 45C Hot 55 C 20 Mins 0. 204 0. 217 0. 322 0. 341 40 Mins 0. 228 0. 232 0. 383 0. 94 60 Mins 0. 228 0. 236 0. 422 0. 427 Standard Deviation for Mean Photosynthesis Rate For Each Temperature Cold 5C Room Temp 25C Mild 45C Hot 550 20 Mins +/- 0. 0456 +/- 0. 0271 +/- 0. 0312 +/- 0. 0477 40 Mins +/- 0. 035 +/- 0. 0208 +/- 0. 015 +/- 0. 0559 60 Mins +/- 0. 048 +/- 0. 0563 +/- 0. 0354 +/- 0. 0616 All Standard Deviations: +/ Analysis Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Analysis The graph above supports the hypothesis that as temperatures of surrounding environments increase, the rate of photosynthesis increases as well.

The graph displays this conclusion as each temperature did increase over time. The data suggests that the hotter temperatures yielded the best and highest rate of photosynthesis. The hot 55C test tube had the highest rate of photosynthesis. This means that the higher the light absorption rate is, the higher the rate of photosynthesis. The data shows that photosynthesis is most successful at warmer temperatures than cold.

The mean absorption rate for the coldest temperature (5C) was 0. 204, 0. 228, and 0. 28 nanometers, while the mean absorption rate for the hottest temperature were 0. 34, 0. 394, and 0. 472 nanometers. The means for the hotter temperature were considerably higher than of any other temperature. This leads to the conclusion that as temperature increases, so does the rate of photosynthe Qualitative Data Each of the test tubes containing the chemical indicator solution turned a dark purple color. This color change is due to the plants use of c02, and the surrounding environment’s need to replace the co2.

The need for co2 in the surrounding environment comes from the increased rate of photosynthesis and intake of c02, therefore creating a need for it in the environment (chemical indicator solution). Hydrogen ions are removed and pH increases with less hydrogen. On the color spectrum, the color appeared purple because of its high pH. The error bars are used in the experiment as a graphical representation of the variability of the data collected. This helps give an idea of exactly how precise a measurement is, and how it deviates from the mean value. The uncertainties represents the reliability of the data.

Evaluation The aim of this experiment was to test the rate of photosynthesis in different temperatures by measuring the percentage of absorbed light in a colorimeter. The research question asks to identify the effect of varying temperatures on the rate of photosynthesis in algae. They hypothesis states that if green algae is exposed to differing external increasing temperatures, then the rate of photosynthesis will increase. The research hypothesis was supported by the results and data found in the graphs. As the temperature increased, so did the rate of photosynthesis.

Also the higher temperatures yielded the best rates of photosynthesis. The means were included in the data to effectively represent the different data in each trial, and the standard deviation was included to tell how far individual data was from the mean/ average. The mean starting rate of the cold environment 5C was 0. 204% and the mean starting rate for the hot environment 55C was 0. 341%. This supports the hypothesis that the warmer the temperature, the higher the rate of photosynthesis. According to Figure 5, the rate of photosynthesis increased as time increased.

The mean values for the starting time (20 mins) were lower than of the end time (60 mins). The data supports the conclusion that the higher the temperature, the higher the absorbance rate and therefore the higher the rate of photosynthesis. The data found in Figures 1-5 support the scientific concept of photosynthesis. Temperature, light, and carbon dioxide are all variables that affect the rate of photosynthesis. Temperature was tested through the experiment. The scientific concept explains that higher temperatures produce a higher rate of photosynthesis.

This conclusion was supported by the data found because the higher temperatures had a higher rate of photosynthesis. In most chemical reactions, the reaction rate increases with temperature. If temperature is cold (between 0 and 10 C), the enzymes responsible for photosynthesis move to slowly to meat the substrate and will be too cold for a reaction to occur. In medium temperatures (10 to 20C), the enzymes responsible for photosynthesis are functioning at their optimal level. This means that the rate of photosynthesis is high.

At high temperatures (usually above 30C), enzyme function begins to slow down and at 40C, the enzyme denatures and no longer functions. The data from this experiment support the concept. However, the enzyme did not denature at the 45C and 55C temperatures. This could be due to external factors such as the fact that the algae was encapsulated in beads as well as in a solution in a test tube, therefore the algae might never have reached 40C. In conclusion, if green algae is exposed to differing external increasing temperatures, then the rate of photosynthesis will increase.

This is due to the enzymes in algae and their ability to function optimally at higher temperatures. Evaluation of Procedures Biological Variation Effect on Data: The enzymes responsible for photosynthesis are, according to the scientific concept of temperatures effect on photosynthesis) supposed to denature at 40Cor higher. However temps. Higher than that were tested and the enzyme continued to photosynthesize. This could be due to the environmental factors. The algae was placed in beads, inside a chemical indicator solution in a test tube. This could mean that the algae never reached 40 C.

Solution for Improvements: Somehow test the temperature of the algae inside the beads. To modify this experiment and test the point that enzymes denature, the algae temperature could be closely watched, and ensured to reach 40C and higher. Systematic Errors Effect on Data: Due to the size of the lab groups, the measurements were not taken at the exact same time for every temperature. Some were roughly 3 minutes after another. Solution for Improvements: The groups could recruit help to ensure there are enough people for each temperature so that the measurements will be taken at the same time.