Free Photosynthesis Lab Experiment Report Sample

Assignment #11. Based on what you already know about photosynthesis, develop a testable hypothesis to explain the influence of an increase in light intensity on the photosynthetic rate in tomato leaves. ( hint: make sure your hypothesis is specific enough such that the results of your experiment will support it or disprove it. For example a BAD hypothesis would be: Increased light allows the plant to grow larger. You are not testing the growth of the plant in this experiment .)Answer
Basing on the experiment, the increase of light intensity increases the photosynthetic rate. It is evident that this rise of light intensity does not affect the rate of photosynthesis. The tomatoes spread their leaves so that each leaf maximizes the amount of light that falls on them. However, too much light damages chloroplast (Blankenship 36).
2. What is the relationship between an increase in light intensity and photosynthetic rate in tomato leaves? Does this relationship support the hypothesis that you formulated?Answer
They both depend on each other since as light increases, the rate of photosynthesis increases also until they reach a point where the rates levels off. It is known that light intensity beyond the plateau curve is called the called the light saturation point of photosynthesis. Increase of light here does not cause an increase in the rate of photosynthesis hence other factors example CO2 level limit the photosynthetic process.
3. Photosynthetic saturation is the maximum rate of photosynthesis. What was the value for photosynthetic saturation in tomato leaves? What value of light intensity produced photosynthetic saturation in tomato leaves? Based on what you know about photosynthesis, provide possible reasons for what causes photosynthetic saturation ( these cannot be determined from the plot, but possible answers can be found in the background reading for this lab ).Answer
Light saturation occurs when CO2 levels off and becomes limiting. The saturation is reached at about 1000mmol m-2s-2 that is a one-quarter to one-half of the full sunlight. Sometimes the saturation level and the influence rate can be increased by the ambient CO2 level.
4. What is the relationship between an increase in light intensity and photosynthetic rate in leaves from a corn plant? How does this relationship compare with what you observed for tomato plants?Answer
The increase of light increases the rate of photosynthesis. It occurs because the photolysis of water is more likely to occur if the light is readily available. Once the graph appears to level off in a certain light intensity, and then there must be some of other factors limiting photosynthesis (Blankenship 14).
5. Photosynthetic saturation is the maximum rate of photosynthesis. What value of light intensity produced photosynthetic saturation in corn leaves?Answer
In each physical factor, there is always a minimum, maximum, and optimum. In order to get the maximum rate of photosynthesis, each of the physical factor has to be optimal. The increase of the light intensity is directly proportional to the maximum rate. There is no exact value of intensity. The greater wattage light source close to the plants and the light rich in blue and red would all be the factor of the intensity.
Assignment 2: Influence of Light Quality on Photosynthesis1. Based on what you already know about photosynthesis, which colors of visible light are most effective for photosynthesis in plants? Which colors of visible light are least effective for photosynthesis? Why are some colors more effective than other colors?

Answer

The experiment shows that red is the least effective while green is the most effective. The experiment shows that green color enhances the photosynthesis rate, and the red color light retards the photosynthesis.
2. Develop a hypothesis to predict the effect of changing light quality from white light to red, green, and blue light on photosynthetic rates in corn.

Answer

The hypothesis in the experiment is to determine whether the color of light reflecting on the leaf has an effect to the rate of photosynthesis.
3. What effect does light quality have on the rate of photosynthesis? Which colors of light were most effective at stimulating photosynthesis?

Answer

The blue color, on the other hand, has the highest influence on the photosynthesis that is the reason as to why the growers are advised to use is when growing plants indoors. Yellow gives the lowest amount of light. Use of white light in an experiment is recommended since it is part of the spectrum of variants and hence serves as a control element in the experiment (Badger & Price 2003).
4. Can you relate your results to the absorption spectra of the photosynthetic pigments?

Answer

Pigments are the molecules with their characteristic absorption spectra in the response to the light. It is indisputable that the pigment color depends on the wavelengths of the light that are not absorbed (Blankenship 2014).
Additional Questions – not found in your lab manual1. In carrying out the experiments in this laboratory, describe the result that was the most surprising? In other words, what did you learn in this lab that changed your understanding of photosynthesis?

Answer

The lab practice has become an important part for me to understand how plants make their food. It is my surprise that plant can photosynthesize even when the light reflecting on the leaves is not white like the one coming from the sun. The leaves under the experiment photosynthesized when green, red, and blue light reflected on them. The only thing that arose from changing the color of light is the rate in which photosynthesis occurs. The green light resulted in the highest rate of photosynthesis while the red light gave the lowest rate of photosynthesis. The lab was a foundation for a better understanding of the effects of temperature, air movement and the light intensity to the rate in which photosynthesis occurs. The lab completely helped me to understand the theoretical work about photosynthesis.
2. Propose a new experiment using the same experimental apparatus from this lab to test another aspect of photosynthesis. You may change any parameter but in answering this question you must tell me the new hypothesis you are testing.

Answer

The main aim of the experiment is to test the effect of the smoothness and roughness of the leaf to the rate in which photosynthesis occurs. The new experiment will compose of a leaf with a rough texture and another leaf with a soft texture. The two leaves will come from two different plants. The parameters for measuring the rate in which photosynthesis occurs will remain the same. The color of lights will remain as the first assignment, but most focus will be on the photosynthetic rate of each of the leaves. On the completion of the experiment, one will be able to tell whether the leave texture is a factor to consider during photosynthesis.
3. Based on the results from the experiments above regarding the saturation points of the corn and tomato leaf, if you performed the same experiments with a cactus leaf then predict how the results might differ.

Answer

The saturation point for the tomato leaf was lower than that of the corn leaf. The two leaves did not differ too much because they grow in the same climatic region. The cactus will require a high temperature and high light intensity to reach its saturation point. Cactus is desert plants that have adapted to the hot and sunny conditions for this reason enabling them to withstand all the fierce conditions. The results will differ completely since the cactus does not rely heavily on photosynthesis because its leaves have changed due to the conditions to become thorns. It will be hard for the thorns to compete with leaves in photosynthesizing.
Part 2:Exported Data and NotesAfter you have completed the experiment you will need to ‘Prepare’ and ‘Analyze’ the data. Your data will be in a table format that you will have the option of exporting data with the Add to Notes button. These notes can be copied and pasted into a Word file. Add all these notes to this section. These notes will be unique to your experiment and should match up with your graphs. Part 3: GraphsCopy and Paste all the graphs related to your experiment in this section. You will need to save all your plots by using the Export Graph function. It is possible to save the graphs as an HTML file or simply copy and paste the graphs into Word.

Exported LeafLab Graph

Note on saving: this is an HTML page containing a graphic file. In order to save this page, you need to save both the HTML page and the graphic file.

The graph of a tomato leaf with no intercepts.

Exported LeafLab Graph
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Tomatoes leaf with negative interceptions

Exported LeafLab Graph
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Tomato graph with positive interceptions

Exported LeafLab Graph
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Corn graph with interceptions

Exported LeafLab Graph
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Corn graph with red light and higher interceptions

Works cited

Badger, Murray.; Price, GD “CO2 concentrating mechanisms in cyanobacteria: molecular components, their diversity and evolution.” Journal of Experimental Botany 54 (383): 609–22. 2003.
Blankenship Robert “Molecular Mechanisms of Photosynthesis (2nd ed.)”. John Wiley & Sons. ISBN 978-1-4051-8975-0. 2014. Print.