Does Temperature Affect the Rate of Photosynthesis? Jackie and Fennell

Higher temperatures will cause photosynthesis to occur more rapidly in plants because as temperature increases, the the molecular activity increases, which causes the reaction to occur faster. Colder temperatures will cause photosynthesis to occur slower in plants because as temperature decreases, the molecular activity decreases, causing the reaction to occur slower. Hypothesis

Independent variable: Temperature temperature changes in each experiment warm solution- 30°C; cold solution- 10°C Control: room temperature (20°C); light and dark controls used to show that the leaves were rising (1.) because of the light (shown by dark control) and (2.) the unaffected, room temperature cups under the light had a different outcome from the cold and heated cups Experimental Control

●Making bicarbonate + soap solution: A pinch of baking soda is added into a plastic cup. Then, 6 cm of water is added, and the solution is stirred until no baking soda is seen. A drop of liquid soap is added, and stirred. The solution is then divided into two cups, and this process is repeated again, resulting in four cups with 3 cm of solution. ●Making leaf disks: Four spinach leaves were collected, and seven leaf disks were punched out of each leaf with a hole puncher. ●Preparing leaf disks: Seven spinach disks were put into a syringe. The soap solution was pulled into the syringe about ⅓ of the way full. A thumb was placed to block the hole at the needle end of the syringe and then the plunger was pulled away from the thumb for seconds. The leaves sank and the solution and leaves inside the syringe were poured into one of the four cups. This was repeated 3 more times Procedure

●To make the warm temperature solution, the solution was heated on a hot plate until it was 30°C. ●To make the cold temperature solution, the solution was put into an ice bath until it was 10°C. ●2 control cups were used. One was put in a drawer (dark) and the other was put under a heat lamp (light). ●The hot and cold cups were also put under the light ●The amount of leaves floating in each of the four cups was recorded every minute for 20 minutes. Procedure continued...

Quantitative Data Time (min) lightdarkwarm with lightcold with light 0: : : : : : : : : Amount of Leaf Disks Floating after 20 minutes

Quantitative Data continued. Time (min.)LightDarkWarm with LightCold with light 11: : : : : : : : : : Amount of Leaf Disks Floating after 20 minutes continued.

Graphs The warm with light slowly increased and stayed the same because all the leaf disks(7) were already floating. The dark consistently stayed at 0 for 20 minutes. The light stayed at 0 for 19 minutes. At 20 minutes 1 leaf disk rose in the light cup. The cold with light rose, then decreased to 0.

In the heated water cup, the leaves rose more than in any of the other cups, from zero leaves to seven leaves after only five minutes, whereas the leaves with cold water rose to three in the middle of the experiment but dropped back down to zero at the end. In the controls, neither of the cups really had leaves that rose, but at the very end of the control with light, one leaf rose. Some unusual data collected was the rise of three leaves in the middle of the cold water cup experiment, because none of the other cups had any leaves rise and then drop down again. Another unusual data point was the light control not having any leaves that rose until the very last minute. In the graph, it can be seen that the heated water (with light) rose very quickly, and much faster than the rest of the cups. Then, the cold cup line shows that the leaves rose and then fell again, twice. With the controls, it can be seen that neither rise until the control under the light has one leaf rise at the last minute (20). The fact that the leaves are rising shows that photosynthesis is occurring, because the process of photosynthesis produces oxygen, which causes the leaf to rise. Also, the heat lamp is like an artificial sun, providing the light energy necessary to photosynthesize. This means that the leafs in the heat water were doing more photosynthesis in less time because more leaves were rising in a shorter amount of time, and the heat lamp was working because no leaves rose in the ‘dark’ cup. Discussion

●The heat lamp was not the same distance from the leaf disks for each solution. o This could have caused the number of leaf disks floating to be lower if it was farther away and higher if it was closer to the heat lamp. ●The warm solution’s temperature was not kept at 30 degrees Celsius o This could have caused the number of leaf disks floating to be lower because the molecules wouldn’t be moving as fast in this environment the whole time which would cause photosynthesis to occur slower. Possible Experimental Errors

●The cold solution’s temperature was not kept at 10 degrees Celsius constantly throughout the experiment o This could cause more leaves to rise because as the water warms the molecules will move faster in this environment, possibly allowing the leaves to photosynthesize more ●The ice in the ice bath of the cold solution blocked the leaf disks from floating to the top o This could have obscured the view of the data collector, causing less leaves to be accounted for, or less leaves to rise to the top Possible Experimental Errors

The heated water cup should have more leaves that rose than any of the other cups because of the molecules moving faster in the warm water, allowing for more leaves to photosynthesize faster, and thus rising more. The cold water cup should have less floating leaves than the hot water because the molecules move slower in the cold water environment, not allowing the leaves to photosynthesize as quickly. The data shows that the heated water cup had the most leaves floating and the cold water cup had less leaves that were floating, and the controls had mostly no leaves to rise, showing that the hypothesis can be accepted. This is because it was hypothesized that the heated water would have the most leaves to rise because of molecular activity, and the data supports it by showing that the leaves in the hot water did rise more than the cold water, and more than any of the other cups’ water solutions. The heated water’s leaves rose to have seven leaves, and the cold water leaves rose for a little, but ended up with no leaves at the top. Conclusion