Will Different Temperature of Water Effect the Rate of Photosynthesis in Baby Spinach Leaves Mikayla, Timmara, Grant, and Michael Methods To complete the experiment, measure 100mL of dH 2 O with a graduated cylinder. Pour this measured water into a plastic cup. Measure 1 gram of baking soda using an electronic balancer. Pour measured baking soda into the 100mL of dH 2 O and stir this solution until there isn’t any baking soda visible. Now, hole punch 10 leaf disks from a healthy-looking baby spinach leaf making sure there aren’t any veins being cut. Measure the temperature of the new bicarbonate solution with a thermometer, it should be about 24 o C; if the temperature is not approximately 24 o C, cool it with an ice cube or heat the water using a heating pad. Once the temperature of the bicarbonate solution has reached a constant 24 o C, take a syringe and place the 10 leaf disks inside of it by detaching the plunger part. Put the plunger part back on the syringe while trying not to squish any leaf disks. Insert an adequate amount of the bicarbonate solution into the syringe containing the leaf disks (about 3mL). Release any excess air from the syringe by pushing the plunger up a little bit. When the excess air has been released, place a thumb over the top of the syringe, so that air cannot enter and water cannot be released out of the syringe. Pull down the plunger slowly while shaking the syringe (a thumb should still be over the top of the syringe). Repeat this step until all of the leaf disks start to sink to the bottom of the syringe. Then release the leaf disk into the plastic cup that contains the bicarbonate solution by slowly detaching the plunger from the syringe (the water also goes back into the plastic cup). Next, assemble the “light box”. Grab the 5.7 L container and make an opening at one of the short length sides (big enough to insert a light bulb base in) using scissors. Insert the light bulb base into the opening, and screw the light bulb into the light bulb base. Measure the temperature of the bicarbonate solution once more to ensure it is at the correct temperature. Place the leaf disks submerged in the bicarbonate solution inside of the “light box”. Plug the light bulb into a socket and turn the light on. Then, record the time when each leaf disks rises using a timer. (Do not reset the timer after each disk rises; keep the timer going, just record the time.) Once all of the leaf disks have risen, start the same process for the next temperature. However, cool the temperature of the bicarbonate solution down to approximately 20 o C by placing the cup into another cup of cold water. Measure the temperature of the solution using a thermometer. Once the leaf disks are sunk into the plastic cup of the bicarbonate solution, place the plastic cup inside of the “light box”. Measure the temperature of the water making sure it is still about 20 o C. Record the time when each leaf disks rises. When this trial finishes, start the process for the next temperature. This trial involves increasing the temperature of the bicarbonate solution to approximately 28 o C by using placing the heat pad. Then measure the temperature of the solution using a thermometer. Once the leaf disks are sunk into the plastic cup of the bicarbonate solution, place the plastic cup inside of the “light box”. Measure the temperature of the water making sure it is still about 24 o C. Record the time when each leaf disks rises. Perform three (3) trials for each temperature (20 o C, 24 o C, and 28 o C) to receive accurate results. Introduction The equation of photosynthesis is as follows: 6CO 2 +6H 2 O+Energy  C 6 H 12 O 6 +6O 2 “Does the temperature of water affect the rate of photosynthesis?” This was the root of the performed experiment. Using spinach leaves, carbonated water, and a fluorescent light bulb, change was seen. Plants living in tropical regions tend to be more exposed to heat. Plants that live in cold temperatures go dormant, but would photosynthesis still occur? And would it be as rapid as usual? Photosynthesis itself is a complex process. For photosynthesis to occur, a photon must strike the leaf. Electrons in the leaf become excited, and they break of and they travel down the electron transport chain. Two electrons will bind to a molecule called NADP +. Two hydrogen atoms also bond to NADP + to form NADPH. Photo system 1 now has an electron hole, which is filled by photo system 2. A process known as photolysis, or the splitting of a water molecule fills the electron hole in photo system 2. A water molecule splits into two electrons, a positive hydrogen atom and a negative hydrogen atom, and an oxygen atom. These electrons fill the hole that was in photo system 2. The hydrogen atoms move into the thykaloid space of a leaf, and as the thykaloid space becomes concentrated with hydrogen, the atoms move through the ATP synthase to form ATP. Two oxygen atoms then combine to form O 2 gas, which are released out of the stoma. Discussion In the experiment, 10 leaf disks were submerged into 3 different temperatures, which were 20 o C, 24 o C, and 28 o C. They were then placed under a 100 Watt light bulb, providing each with the same amount of radiation. When each leaf disk rose to the surface of the water the time was recorded, which estimates the time each leaf disk took to complete photosynthesis. The hypothesis used was: “If we place leaf disks in different temperatures of water, the warm water will display an increased rate of photosynthesis because in the tropics, where it is warmer, there are more and taller plants. During the three trials, the 28 o C water submerged leaf disks showed the fastest rate of photosynthesis. The 20 o C and 24 o C water immersed leaf disks came in a close tie. The average time of completion for the 28 o C water immersed leaf disks was less than seven minutes; all ten of the 24 o C water submerged disks rose in less than fifteen minutes; and the 20 o C water submerged leaf disks rose in about fourteen minutes. However, the trials had an expiration time, which was the twenty minute mark. In two of the trials for the 24 o C leaf disks, five to six disks did not rise, and in one trial for the 20 0 C water submerged leaf disks, two of the disks did not rise. It can be assumed that if allowed more time, all of the leaf disks would rise. When evaluating the data, there were some trends detected. The 20 o C water submerged leaf disks did not have much of a trend; however, two of trials had similar times, which were the first trial and the third trial. The second trial was unique because the first leaf disk did not rise until 15 minutes passed, but after the first one rose, the other leaf disks rose fairly quickly. In the 24 o C trials, there would have been a trend; however, one leaf disk was not able to sink to the bottom of the plastic cup. These trials were extremely usually. The 28 o C water submerged leaf disk rose fairly quickly, with one trial being completed in a little less than four minutes. It is extremely imperative to eliminate any variables that may affect the experiments accuracy. However, it may be nearly impossible to have a completely variable-free experiment. In the experiment, multiply variables might have disturbed the reliability of the data. It might be fairly hard to keep a constant temperature 4 o C less and above the average temperature. This could have been solved with cooling the water with a different method, such as pre- freezing the water or using cold facet water, and using hot water from a water facet. Also regarding temperature, it can be difficult to place a thermometer into a plastic cup full of leaf disks without accidently disrupting the water or touching a leaf disk. This can be resolved by taping the thermometer inside of the plastic cup, so that it is not being removed and inserted multiply times. The final observation made during the experiment has to do with the leaf disks their selves. It was noticed that the leaf disks that did not have any veins and that were not bent rose quickly. Making sure the leaf disks are vein-free and unbent can easily solve this problem. The 28 o C water submerged leaf disks displayed the fastest rate of photosynthesis with an average of the trials being finished in about six and a half minutes. This data agrees with the hypothesis created because 28 o C is the warmest temperature out of the three temperatures. Although some errors might have occurred, the data still proves that the hypothesis is correct. From the data record from the experiment, it can be assumed that warm temperatures of water shows a greater rate of photosynthesis than colder water temperatures. Figure 1: Grant Durbahn recording the time each leaf disk rises using a timer. Figure 2a: Healthy leaf disks cut from baby spinach leaves with a hole puncher. The plunger part of the syringe is detached and ready for leaf disks to be inserted. Figure 2b: Leaf disks have sunk inside of the bicarbonate solution filled syringe. Results Figure 2a Figure 2b Figure 3: Items that may be used during the experiment. Also the completed “light box” used for the light source. References bio%20101/bio%20101%20lectures/photosynthesis/photosy n.htm