1/9/2024 0 Comments Spinach disk graph title![]() A measure of photosynthetic rate in spinach leaf disks.To adjust for this, use the inverse, \frac for each of the conditions and graph the results. It would be easier to understand the meaning of the statistic if it were directly proportional, as the rate of photosynthesis increased the statistic is larger. We can conclude that the ET 50 statistic is indirectly proportional to the rate of photosynthesis, the higher the rate of photosynthesis, the smaller the ET 50 statistic. We would expect the rate of oxygen produced to be high and the time at which 50% of the disks are floating to be comparatively short. In a strong light situation, photosynthesis would proceed more rapidly.We would expect the rate of oxygen produced to be low, and the time at which 50% of the disks are floating to be relatively long. In a low light situation, photosynthesis would proceed at a relatively slow rate.How do we interpret ET 50? Let's consider how ET 50 varies as the rate of photosynthesis varies. Using the graph, estimate the time at which 50% of the disks are floating, ET 50.Graph the results using time as the independent variable.Use the following to help make sense of the data The raw data from the procedure is the number of disks floating at each minute mark, until all of the disks are floating. Use the protocol specified in The Floating Leaf Disk Assay for Investigating Photosynthesis.įor a video demonstration of the infiltration technique, see. Prepare a data table to record the results of the process. Leaf material (spinach and ivy work well).Plastic syringe with needle removed (10 cc or larger).Use the following procedures to become familiar with the basic protocol. Printout the materials and procedures for reference during the lab. An Introduction to Photosynthesis and its Applications.In preparation for the experiment, read about photosynthesis (and optionally cell respiration) in a textbook or at one of the following sites: 2 Basic floating leaf disc assay protocol.In this lab, the rate at which small leaf "disks" rise to a floating position will be used as an indirect measure of the net production of oxygen produced by photosynthesis. If/when the leaf floats, it is because the net result is more oxygen produced by photosynthesis than used in respiration. Isn't the leaf also engaged in respiration, which would use the oxygen produced by photosynthesis? The answer is yes, some of the oxygen will be used in the leaf's respiration process. As it is produced the oxygen gas will form small bubbles which will cause the leaf to again float.īut wait a minute. By providing the requirements for photosynthesis (light, CO 2, and H 20), oxygen will be produced in the leaf, even though the leaf is "underwater". When these intercellular spaces are instead filled with solution, the density of the leaf increases and it sinks. Generally speaking, a leaf floats (due to the many intercellular spaces used for exchange of gases). This lab uses the floating disk leaf assay as a vehicle for exploring the action of photosynthesis in plants. ![]() It uses material from the article " Photosynthesis", retrieved. This extract is licensed under the Creative Commons Attribution-ShareAlike license. In plants, algae and cyanobacteria, this is done by a sequence of reactions called the Calvin cycle. These electrons are then used in the reactions that turn carbon dioxide into organic compounds. ![]() The rest of the energy is used to remove electrons from a substance such as water. Some of the light energy gathered by chlorophylls is stored in the form of adenosine triphosphate (ATP). In plants, these proteins are held inside organelles called chloroplasts, while in bacteria they are embedded in the plasma membrane. For example, the process always begins when energy from light is absorbed by proteins called photosynthetic reaction centers that contain chlorophylls. The overall equation for the type of photosynthesis that occurs in plants is:Ħ CO 2 + 6 H 2O + Light → C 6H 12O 6 + 6 O 2Īlthough photosynthesis can happen in different ways in different species, some features are always the same. Photosynthesis changes the energy from the sun into chemical energy, splits water to liberate O 2, and fixes CO 2 into sugar.
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