Bryan Barrington
Mr. Dickson
AP Biology Honors
11/16/17
Photosynthesis Lab Report
BACKGROUND/PROBLEM STATEMENT:
	The purpose of performing the lab is to better our understandings of the processes of photosynthesis. Photosynthesis is an essential process that is carried out by plants. Photosynthesis can be seen as a redox reaction. Photosynthesis reverses the direction of electron flow. First the water is split. Following that electrons are transferred along with hydrogen ions from the water to carbon dioxide, reducing it to sugar. Plants go under the category of autotrophs. They are called autotrophs because they are able to make their own energy without consuming it from another source. The process, photosynthesis, is what makes the energy for the plant.  Photosynthesis begins with light breaking down water. According to The Cell it states, “The chloroplast splits water into hydrogen and oxygen” (184). Light helps begin the photosynthesis process. However, different waves of light affect how well the plant is able to go through photosynthesis. Chlorophyll within the plant take the light and turns it into a usable energy source for the rest of the various functions that occur in photosynthesis. The different wavelengths of the light dictate how fast the process as the chloroplasts like different wavelengths of light. Blue, violet, and red wavelength light is typically what the chloroplasts like. Chlorophyll is the pigment that makes plants green. Green is the least efficient light wave because that is the color the plant is reflecting. However there are other accessory pigments called carotenoids. These hydrocarbons are various shades of yellow and orange as they absorb violet, blue, and green light. This makes the spectrum of colors that can drive photosynthesis larger. There are also processes that harvest light. These processes are called photosystems. Photosystems are composed of a reaction center surrounded by a number of light-harvesting complexes. Each of these complexes contain pigment molecules. The pigment molecules allow for a large capture of light over a larger surface area with an extension of the spectrum of light that can be absorbed. With this light it is then funneled to a reaction center. A reaction center is a protein complex that has two chlorophyll a molecules. The chlorophyll a molecules allows the transfer of an electron to a primary electron acceptor. There are two photosystems. Photosystem I and photosystem I. The chlorophyll a in photosystem II is called P680 because this pigment is best at absorbing light having a wavelength of 680 nm. The chlorophyll a in photosystem I is called P700 because it absorbs 700 nm most efficiently. The chlorophyll a in the photosystems are identical -- they differ because of the proteins they are attached to. Light drives the synthesis of NADPH and ATP through the photosystems. The key to this process is flow of electrons through the photosystems. This process is called noncyclic flow. Noncyclic flow has 7 main steps, they go as follows: Light into pigment molecule, electrons are captured by primary electron accept, an enzyme splits a water molecule into two electrons, the electrons then pass from the primary electron acceptor to an electron transport chain, there is an exergonic fall of electrons that lower the energy level, THe photoexcited electron is captured by photosystem I, electrons from photosystem I go down a second electron transport chain, lastly, the enzyme NADP+ reductase transfers electrons to NADP+. There is also a second flow that occurs during photosynthesis which is called cyclic electron flow. Electrons in this process take an alternate path. Electrons cycle back from ferredoxin to the cytochrome complex and from there continue on to a the chlorophyll a in the PSI reaction center. Photosynthesis can be summarized with the formula 6CO2 + 6H2O C6H12O6 + 6O2 . The formula shows carbon dioxide, water, and light energy used to make the by-products, glucose and oxygen. There are two stages of photosynthesis. One of the stages is light reactions. Light reactions convert sunlight into usable energy. Light absorbed by the chlorophyll moves hydrogen from the water to an acceptor called NADP+. Light reactions then reduce NADP+ to NADPH by adding electrons along with hydrogen, called H+. Light reactions also house a process called photophosphorylation. Photophosphorylation is the generation of ATP using chemiosmosis to add a phosphate group to ADP. The second stage of photosynthesis is the Calvin cycle. The Calvin cycle begins by using CO2 and putting it into organic molecules in the chloroplast. Next, the carbon is reduced into a carbohydrate by the addition of electrons. Reduction is able to be carried out due to the NADPH made by light reactions. From this the Calvin cycle is able to make sugar, but it needs NADPH and ATP to do so. The steps within the Calvin cycle are referred to as the dark reactions because they do not require light directly. The Calvin cycle usually occurs during the daytime. There are three main processes of the Calvin cycle. The first is carbon fixation, which inputs carbon dioxide that attaches to a five carbon sugar. An enzyme called rubisco catalyzes it splitting it into two 3-phosphoglycerate. The next step is reduction. The third is regeneration of the CO2 acceptor. Photosynthesis still possesses ancestral processes. One of the plants that uses these old processes is C3 plants. C3 plants, a category of plant that uses the Calvin cycle, make a three carbon sugar hence its name C3. These plants partially close their stomata on hot days. When the stomata is closed they make less sugar because of the the level of CO2 in the leaf which starves the Calvin cycle. Rubisco adds oxygen to the Calvin cycle instead of Co2. This splits a two-carbon compound in the leaves. Because of this odd process it produces no ATP because its process consumes sugar. C4 plants have an alternate way of carrying out carbon fixation that forms a four-carbon compound. C4 plants have two distinct types of photosynthetic cells. These two cells are bundle-sheath cells and mesophyll cells. Bundle-sheath cells are arranged into tightly packed sheaths around the veins of the leaf. Between the bundle sheath and the leaf surface there are mesophyll cells. The Calvin cycle takes place in the bundle sheath cells. In the first step, PEP carboxylase is added to CO2, forming a four-carbon compound. After forming this the mesophyll export the four-carbon compound to the bundle sheath cells. The four-carbon compound then releases CO2 which is put back into organic material by rubisco. The CO2 stays in the bundle sheath cells so that the rubisco can bind them. In this way C4 minimizes photorespiration and enchants sugar production. The final ancestral plants are CAM plants. CAM plants store water. These plants open their stomata during the night and open them during the daytime. When there is stomata is open during the night they take up CO2 and turn them into organic acids. During the day the light reactions supply ATP and NADPH for the Calvin cycle.
PROBLEM STATEMENT:
In the lab the question does color affect the rate of photosynthesis was investigated? The independent variable for the lab was the color that the disk of spinach were exposed to. The dependent variable for the lab was the production of oxygen. Based on these variables and background information it was hypothesized that if the color the disks were exposed to was red then the disk were produce oxygen at a faster rate than the others because the chlorophyll like the red wavelength. Our control group in the experiment was the clear plastic wrap. The wrap didn’t expose the disk to a different wavelength in its environment. Constants that were met in order to maintain only one independent variable was the amount of disk in each of the containers, the amount of water in each of the cups, and the time the disk were exposed to the light.
MATERIALS/EQUIPMENT:
Safety Goggles
Notebook
Pencil
9 Plastic Cups
3 Different Color Plastic Wraps
Hole Puncher
Sufficient Supply of Spinach
Bicarbonate Solution
Syringe
Graduated Cylinder
PROCEDURE:
Get safety equipment
Gather materials
Setup lab
Wait for teacher to start you
Fill each of the plastic cups with 200 mL of bicarbonate solution with soap
Gather 9 plastic wrap with 3 different sets of color
Punch out 10 disks of spinach with the hole puncher
When done with the 90 disks place 10 into a syringe
Fill the syringe with 10mL of bicarbonate
Place your finger above the syringe and pull the handle back to suffocate the disks
When the disks begin to sink place them in the plastic cups
Start each of the cups 1 minute after the previous
Repeat steps #9, #10, #11 for the other 80 disks
Record data after every 3 minutes
Clean up any messes that may have occurred
Put away materials
Wait for teachers further instructions
MEASUREMENTS:
	For each of the plastic cups 200mL of the bicarbonate solution was poured in. 10 spinach disks were punched out and placed in each of the 9 plastic cups. Each of the disks were recorded at 3 minute intervals and were exposed for a total amount of time of 12 minutes. 3 sets of different plastic wrap of varying color were used; there was 9 pieces of plastic wrap in total.
EXPERIMENTAL CONTROL:
	In the experiment the controls were closely monitored to maintain the independent variable. In the lab conducted the amount of bicarbonate solution was kept the same. This is important so that the disks were submerged in the same environment. A second control that was monitored to maintain a single independent variable was the amount of disks. This was important because it gave precision to the data. A third control that was maintained to keep a single independent variable was the time the disks were exposed to the light wavelength. This is important because it did not allow other disks to have more time to go through the process of photosynthesis. Allowing extra time would allow each of the disk to produce more oxygen -- ultimately alternating the data. A fourth control maintained was the amount of bicarbonate the disk were exposed to in the syringe. This is important because this could have affected the amount of suffocation able to be done.
OBSERVATIONS:
	In the mini lab conducted different colors were used to see the rate of photosynthesis in duckweed. In the beginning of the experiment no bubbles were visible at the surface. After a couple of minutes a few bubbles started to accumulate. However, toward the end of the experiment of the bubbles diluted and ceased to be present. In the photosynthesis lab, after punching the spinach out, the spinach began to turn a dark green toward the outside of it. When the spinach disks were placed in the syringe to be suffocated bubbles formed occasionally as the handle was pulled down. Once the air escaped the bubbles disappeared. When the spinach disk were placed in the water some sank immediately and few others either floated or remained in the middle of the container.







TABLES/CALCULATIONS:
Photosynthesis Lab (Main)
The Effect of Different Color Types on The Production of Oxygen
Time (mins)
Color Type
0
3
6
9
12
Average Disk Floating
Clear
0
0
0
0
0
0
Red
0
0
0
3
5
1.6
Green
0
0
6
6
8
4

Mini Photosynthesis Lab
The Effect of Different Color Types of The Bubble Production



























































GRAPHS:




DATA ANALYSIS:
	In the main photosynthesis lab the data in each of the containers of different colors was measured at a 3 minute interval. As seen by the data table and graph the green had the most spinach disk floating. The container covered by the red plastic wrap had the second most disk floating and the clear plastic wrap had the least with 0 floating. The average amount of disk that floated in the green covered container is 4. In the red container the average is 1.6 disks floating. In the clear container the average amount of disk floating is 0.
CONCLUSION:

Work Cited