Preliminary Work:
– Establish the distance from the light to produce bubbles from photosynthesis. (10cm)
– How long for the cut (i.e. traumatized) to recover and photosynthesize. (?)
– Is the 1L beaker necessary or not? (Possibly)
Problem Question: What effect does temperature of the water surrounding a Ceratophyllum Demersum have on the rate of photosynthesis?
Photosynthesis Equation: (CO2) + (H2O) + Light Energy (C6H12O6) + (O2) + (H2O)
Background Information:
According to a study done by the University of California, the photosynthetic cells of C.demersum plants are unique among land plants but extremely similar to algae because they typically contain one giant chloroplast with distinct visible compartments located inside of the large chloroplast. This explicitly proves that hornworts are much like most bryophytes as a result of their moss like structure and function. Bryophytes are small, non-vascular plants, like mosses, similar to hornworts. They play a significant role in regulating ecosystems considering they provide an important ecosystem for other plants, which benefit from the water and nutrients that bryophytes collect and produce. Bryophytes can also serve as a good indicator of the habitat quality around them as many plant species in this group are sensitive to levels of moisture in the atmosphere.
The hornwort species is one of the earliest plant groups to evolve stomata. hornwort stomata are large and scattered on an enlarged area of the stem that holds the organs of a flower called a sporangia, where asexual spores are formed. Guard cells that are located in the leaf epidermis collapse inward, they also increase in surface area. One trait that is unique to hornwort is that the pores are perpetually open and are consistently open with the inactivity of hornwort stomata, once open, they are locked in position. The scattered stomata of the hornwort resemble fossil plants in the Devonian and Silurian geologic time period, in terms of size, distribution, and the morphology of the plant, therefore, decipher the origin and evolution of these important structures in plants. In vascular plants, stomatal movement involves a response to environmental cues through active changes in guard cell turgor pressure by hormonally signaling that produces rapid osmotic change. Active and constant movement of stomata appears to be absent in the hornwort plant.
Limiting Factors in Experiment:
– Light Intensity
– Amount of Carbon Dioxide Levels
– Temperature
This experiment is critically dependent upon variables. Limiting factors are the factors that directly affect the rate of photosynthesis. Although photosynthesis is affected more greatly by one of these limiting factors, the rate of photosynthesis can be manipulated through all three limiting factors. (Light intensity, amount of carbon dioxide released, and the temperature of water that the plant or species is placed in.) In regard to the difficultness of measuring sugar (glucose) levels produced during the process of photosynthesis, utilising the amount of carbon dioxide released from plants is used to measure photosynthetic rates. Limiting factors can also be classified as those that include the time of day whether during the day or at night. Although light dependent reactions of photosynthesis are not affected by changes in temperature, the light independent reactions of photosynthesis are dependent on temperature.
Above peak temperature, the rate of photosynthesis begins to decrease, as enzymes are denatured, until it the rate of photosynthesis eventually plateaus. Denaturing in this case occurs due to the high heat temperatures. These denatured enzymes are also proteins, that speed up the rate of chemical reactions that take place within cells and specifically chloroplasts. These enzymes that exist in plant cells work consistently until they are dissolved or become denatured. When enzymes denature, they are no longer capable of being active and become uncapable of functioning properly. This changes the form and shape of the enzyme making it harder for it to function properly in a plant cell during the photosynthesis process. Renaturation is able to occur during this process of photosynthesis.
Figure 1. Denaturing of a protein/enzyme.
Prediction:
Between 0 and 10 degrees Celsius the enzymes that complete the photosynthesis process can’t function proficiently, this declines the photosynthetic rate in the plant. At medium temperatures, between the range of 10 to 20 degrees Celsius, the photosynthetic proteins work in ideal conditions, this affects photosynthesis rates meaning they will produce/release a higher amount of carbon dioxide into the atmosphere. At temperatures over 20 degrees Celsius, the rate of photosynthesis decreases because the enzymes do not work as proficiently at this temperature. This is despite the increase of carbon dioxide diffusion into the leaves. When the temperature rises to 40 degrees Celsius, the proteins that complete photosynthesis lose their shape and denature, this makes the photosynthetic rate decline rapidly.
Figure 1.2 Rate of Photosynthesis
The peak temperature in which the hornwort plant reaches optimum performance will be the medium temperature as a result of the proteins working in ideal conditions. The affect will be a higher amount of carbon dioxide released.
The hornworts habitat is native to North America. The structure of this plant is conclusive to show the following:
• When CO2, light, and other factors are not limiting, the rate of photosynthesis increases with a rise in temperature
• Over a range from 6°C to about 37°C
• Above this temperature there is a fall in the rate and the tissue dies at 43°C
• High temperatures cause the inactivation of enzymes and therefore affect the enzymatically controlled “dark” reactions of photosynthesis
• Optimum temperature for maximum falls is between 20-30°C
• The rate of diffusion of CO2 to the chloroplasts is accelerated by high temperature
Materials:
• Ruler (30cm)
• Scissors
• Lamp
• Hornwort Plant
• 250 ml beaker (1)
• Boiling Tube
• Ice
• Tap Water
• 2 Water Baths (2 different temperatures)
• Thermometer
• Distilled H20
• Test tube rack
• Camera (phone camera)
Procedure:
1. Cut the hornwort plant to a relative length of 5 cm.
2. Place the cut hornwort plant into the boiling tube.
3. Place the hornwort plant into the boiling tube and fill the boiling tube with tap water.
4. Fill one 250ml beaker up with 200ml of distilled water (three different temperatures) and place the boiling tube with the hornwort plant into the distilled water beaker.
5. Place a thermometer inside the distilled water to test the water’s temperature. Record the temperature of the water on the results table.
6. Place the lamp 5 cm away from the beaker, using the 30 cm ruler.
7. Turn off the lights located in the room. Turn on the lamp.
8. Set up the phone camera with video setting to record video for two minutes and thirty seconds of carbon dioxide bubbles.
9. While the recording, count the amount of bubbles that come to the surface of the boiling tube.
10. After completing step nine, remove boiling tube from the beaker and place it on a test tube rack to allow the plant to recover from the process of photosynthesis.
11. Repeat steps five to ten with three temperatures of water for three trials.
Observations:
In this experiment we conducted three separate trials for each temperature we tested in order to collect accurate data. From the data collected there is a trend that for each temperature we tested, with an exception of the room temperature water, all three tests we performed were conclusive to show that they produced a higher amount of carbon dioxide bubbles than the initial trial. We also determined that the trials or tests with higher temperatures produced a higher amount than the previous trial. The high temperature of 45°C produced the highest amount of carbon dioxide bubbles. Our tests also showed that when the hornwort plant was left in the water baths for a longer period of time, they produced more carbon dioxide bubbles.
Figure 1.3 Temperatures Effect on Photosynthetic Rates
Figure 1.3 demonstrates that the rate of photosynthesis gains momentum when the temperature of the water bath rises allowing it to release carbon dioxide into the atmosphere.
Conclusion:
Finally, it may be concluded that the rate of photosynthesis is completely dependent upon variables such as light intensity, amount of carbon dioxide levels, and the test we preformed, temperature. Each temperature tested resulted differently than all other trials preformed. The results we collected disagree with the diagram presented above. The results we collected are anomalous to what is typically concluded in this lab. In my prediction, I stated that the peak temperature in which the hornwort plant reaches optimum performance will be the medium temperature as a result of the proteins working in ideal conditions. As we preformed the experiment, I sensed the prediction I made would fail and be incorrect.
In the lab we preformed, our results don’t show any data that shows proteins denaturing, instead, throughout the lab, the amount of carbon dioxide bubbles that were released continued to grow rapidly with the increase in temperature each time. This is anomalous data because it is conclusive to show that most proteins in this state of photosynthesis will go denatured, but in our own experiment the proteins didn’t change shape and stayed fully functional in thee presence of varied temperature waters. The conclusion does not support the prediction because it is shown that the proteins did not denature, because they seemed to stay alive throughout the entirety of the experiment. The pattern of evidence is as temperature increases the amount of carbon dioxide released into the surrounding atmosphere also increases.
Particles: Cells:
– Carbon Dioxide
– Oxygen
– Water
– Concentrations (High to Low) – Structure and Function of Leaf
– Cells and Organelles
– Chloroplasts
– Volume
– Surface Area
Forces: Energy:
– Collisions
– Concentration Gradients
– Pressure – Heat
– Light
– Spectrum (ROYGBV)
– Chloroplast Use
Evaluation:
Previously stated, this experiment is critically dependent on upon specific variables used in the experiment. Since that is a statement that is crucial on how it affects the rate of photosynthesis, I have analyzed what could be improved in this experiment in order to make less anomalous data and to make the results we collect more accurate. To make this experiment as accurate as possible, the sources of light should be tested prior to performing the experiment, this way we can record the wattage of the light fixture (lamp) that we are using in the experiment. Furthermore, in regard to interference with the sources of light is the amount and intensity of other light sources either promoting or demoting the rate of photosynthesis. While performing this experiment I noticed that the lights that were switched on in the room might have severely affected the rate of photosynthesis considering photosynthetic rates are critically dependant on manipulated variables such as that of light intensity. A possible improvement would be to have a way to double check or confirm the amount of carbon dioxide bubbles released. This improvement could be made using a CO2 gas sensor to monitor and record levels of carbon dioxide. Another improvement to this experiment I could suggest would be for all people who are completing this experiment to use the same length of hornwort plant for each variable. And to use a new section of hornwort plant for each set of trials or temperatures. These improvements to the experiment will allow for more accurate data/results and will make further connections and investigations into the experiment to allow us to network to other topics and units in the science curriculum. Furthermore, to make this lab more consistent and reliable, I don’t believe the 1L beaker is completely necessary testing the effect of changing temperature on photosynthesis on hornwort plants. Additionally, the suitability of the procedure used in this experiment could be improved to provide clarity for the scientist. We could improve this issue through the use of consulting with a science teacher or consulting with a professional chemist. The evidence collected in this experiment could greatly improve with more precision of focus on the student’s responsibility. The reliability of the evidence in the lab is completely dependent on the focus of the students preforming the experiment. All the results stated in the evidence are presumed reliable unless anyone sees an issue with the way of collecting the evidence. The experiment is considerably varied because of the many problems and issues that can occur while performing the experiment. To ensure the reliability and accurate results of this experiment I believe we should perform a second version of the experiment.