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Lab Report On Vegetable Pigments And Photosynthesis Biology Essay

The purpose of this laboratory was to see distinct and identify the pigments of spinach skin cells by using paper chromatography. Through this laboratory, one can understand the rate of photosynthesis and absorbency rate of chloroplasts in various light intensities.


Paper chromatography can be used to separate also to identify the mixtures of pigments and other substances of a chemical. In chromatography the solvent moves up a piece of newspaper by capillary action, which occurs because of the appeal of the solvent molecules to one another and the skinny paper. As the solvents steps up the newspaper it separates the pigments into its components. The chemicals that have emerged on the paper are flower pigments. Herb pigments are chemical compounds that absorb certain wavelengths of light while reflecting others. Some of the light consumed will be used for chemical type reactions as the other mirrored wavelengths will determine the color the pigment will be may actually the eye.

Chlorophylls are greenish pigments that contain a special structure to provide energized electrons to other molecules. There are several types of chlorophyll but the most crucial one if chlorophyll a. Chlorophyll a moves its energized electrons to substances that will make sugar and other sugars. All plant life that photosynthesize consists of chlorophyll a, while, chlorophyll b is a second kind of chlorophyll occurring only in renewable algae plants. Accessories pigments absorb light energy and transfers energy to chlorophyll a during photosynthesis. Two accessories pigments are carotenes and xanthophylls. Carotene is the most soluble pigment because it makes no hydrogen bonds with cellulose, a major component of cell walls, so this pigment will be transported furthest by the solvent. Xanthophyll isnt taken as far as carotene since it is less soluble and is also slowed up by the hydrogen bonding to cellulose. While using solution, R(f)= distance pigment migrate (mm) / distance solvent forward migrated (mm), one can determine the distance relocated by the pigment to the distance transferred by the solvent. Pigments shoot the light energy necessary for photosynthesis.

Photosynthesis is an activity that uses the from sun rays and converts the carbon dioxide into organic compounds, like sugar. The formula for photosynthesis is 6CO2 + 6H2O (with light energy) --> C6H12O6 + 6O2 where we see that carbon dioxide with water and light energy makes glucose and oxygen. You will discover two parts in photosynthesis the light dependent reactions and the dark reactions also known as the Calvin cycle. Light reaction occurs in the thykaloid membranes of chloroplasts and turns light energy into chemical energy. Chlorophyll and beta- carotene are in the thylakoid membranes and mixed up in light reaction. Each one of the pigment passes the power they absorb from light to the chlorophyll molecule to do photosynthesis. In the light reliant process, light energy is consumed and the electrons are boosted to an increased energy level. After a series of reactions, the is then concerted along an electron transportation process and ATP and NADPH is produced. In this process water assists as a by-product of the reactions. The ATP and NADPH are used in the dark reactions as energy for carbon fixation, a process where skin tightening and is changed into carbohydrates and sugars. This process occurs in the stroma of chloroplasts. RuBP captures six substances of carbon dioxide and finally produces one molecule of sugar. ATP and NADPH are made in light reactions and are used at night reactions, after put it to use results to light reactions as NADP+ and ADP which doesnt contain much energy.

In this laboratory, a spectrophotometer was used to measure the level of light transmitted in the chloroplasts of spinach leaves. Chloroplasts from spinach leaves were taken and put into tubes so one can understand the rate of photosynthesis in spinach cells at different light intensities. With this lab, a dye reduction strategy was used. A solution called DPIP (2, 6-dichlorophenol-indophenol) was used in place of the NADP. Since DPIP has a dark blue color, DPIP was used during the lab showing that photosynthesis was happening in the cuvettes. A cuvette is like a tiny test pipe that fits correctly into the colorimeter. The colorimeter is a laboratory material that steps the quantity of light soaked up by the solution. If the light shines on the chloroplasts, the light energy will boost the electrons to higher energy levels and will reduce DPIP. A reduced amount of DPIP will change the color in the pipes from blue to colorless so you can judge the colour change of the chloroplast solutions


First we fired up the flood light already prepared for us, and placed a 600mL beaker of water before it to safeguard the chloroplasts from being heated up by the overflow lamp. This was done to prepare for the next part of the laboratory. Then we ready for the first area of the laboratory. First we obtained a bit of filter newspaper, spinach leaf, and a penny. Then we obtained a vial with 1 cm of solvent in underneath. We ensured the filter newspaper match the vial and minimize a point at one end of the paper. We used pencil to get a lines 1. 5 cm from the point just trim. Then we positioned the spinach leaf together with the filter paper and began to crush the cell pigments onto the filtration system paper just above the pencil collection using that cent. We did this step several times using different spots of the leaf every time. Then we put the chromatography newspaper in the cylinder and ensured the point than it is hardly in the solvent. Then we sealed the lid of the cylinder and waited for the solvent to attain about 1 cm from the most notable of the filter newspaper. We removed the paper and quickly designated the location of the solvent front side. Then we measured the distance each pigment migrated front the idea of the pigment origin to underneath of the separated pigment group. Then we documented the length each front migrated and saved our data. Directly after we finished this part of the lab, we ready for the next part of the lab.

First we connected the Colorimeter with the computer interface. Then we obtained 4 cuvettes and their lids. We designated one (BL) for empty, one (U) for unboiled, one (D) for dark and one (B) for boiled. The blank cuvette was used as the control and no DPIP was added. The cuvette proclaimed (U) was to see the absorbance of light with unboiled chloroplasts. The (B) was to start to see the absorbance of light with boiled chloroplasts. The (D) is perfect for unboiled chloroplasts in the lack of light. We protected all four factors and bottoms of the (D) cuvette with metal foil. Then we added the phosphate buffer, distilled H2O, and DPIP to each cuvette. Inside the blank cuvette we fell 1 mL of phosphate buffer, 4 mL of distilled normal water, and 3 drops of unboiled chloroplasts. Then in the (U) cuvette we added 1 mL of phosphate buffer, 3 mL of distilled drinking water, 1 mL of DPIP and 3 drops of unboiled chloroplasts. At night cuvette, we added 1 mL of phosphate buffer, 3 mL of distilled drinking water, 1 mL of DPIP and 3 drops of unboiled chloroplasts. Finally in the (B) cuvette, we added 1 mL of phosphate buffer, 3 mL of distilled normal water, 1 mL of DPIP and 3 drops of boiled chloroplasts. Following this we calibrated the colorimeter. We made sure the exterior of the cuvettes were clean and free of fingerprints. Then we opened up the lid of the colorimeter and placed the blank cuvette inside. (The calibrate part was done by the tutor). After we calibrated the colorimeter, we placed all three of the cuvettes before the beaker and light. After waiting for 5 minutes we removed the cuvettes from the light and put the (U) cuvette in the colorimeter. Directly after we closed the lid, we waited for 10 a few moments and documented the absorbance value. When it was done calculating we located the cuvette before the light and beaker. Then we performed the same thing with the (D) cuvette and (B) cuvette immediately after. Then we waited for another 5 minutes, we did the same thing and put each cuvette in the colorimeter. After documenting the info we placed them in front of the light again. After another five minutes removed the cuvettes from the light and took turns placing them in the colorimeter. When the info was saved we located them in front of the light for the ultimate trial. When time was over we put them in to the colorimeter and recorded the results. When we finished the lab, we cleansed up and poured the cuvettes made up of DPIP into a particular beaker and poured people without down the drain. We switched off the computer user interface and colorimeter and wiped the tables.


I predict that the dark cuvette (D) and the cuvette with the boiled chloroplasts in the light (B) will have moderate changes in the reduction of DPIP; while, the cuvette with unboiled chloroplasts in the light (U) will have the best reduced amount of DPIP.

Conclusion and Error Analysis:

My results recognized my hypothesis. I forecasted that the dark and the cuvette with the boiled chloroplasts in the light will have somewhat changes in DPIP and that the cuvette with the unboiled chloroplasts will certainly reduce more DPIP.

Everything that occurs during photosynthesis needs the vitality from light, even the dark reactions because the dark reactions need the products of the light reactions to properly function. At night cuvette, although chloroplasts are unboiled, the cuvette was completely protected in light weight aluminum foil. The foil functions as a barrier between your light and chloroplasts. So, the chloroplasts could not properly absorb the light. Therefore, the DPIP was only marginally modified. The boiled chloroplasts did not reduce much DPIP since when the chloroplasts were boiled, it denatures the chloroplasts combined with the enzymes within them so they could no longer properly function. DPIP is reduced when light grows to the chloroplasts and the enzymes are boosted to a higher level of energy. But the chloroplasts and the enzymes are already non-functional so even if light were to reach it, it could no longer perform photosynthesis. The cuvette with the unboiled chloroplasts in the light had the highest reduced amount of DPIP because this cuvette gets the proper conditions for photosynthesis to occur. Unlike the other cuvettes, that one has light and the chloroplasts were not denatured from boiling. When the light come to inside the chloroplasts the enzymes inside was also boosted to an increased level of energy. DPIP is normally blue however when it is reduced, or when more electrons are gained it transforms colorless. So as more and more electrons were boosted and much more electrons were gained, the DPIP was little by little reduced along using its color. Many resources of errors would have occurred but one of them was that the cuvettes were most likely not handled well before they were placed in to the colorimeter. We didn't deal with the cuvettes only by the most notable edge of the ribbed edges but we handled the 4 attributes of the cuvette as well. This probably left a great deal of fingerprints that may have clogged the light to type in the chloroplasts at its potential and cause the colorimeter to miscalculate the quantity of DPIP reduced. When inserting the 3 cuvettes before the light we did not keep in mind the positions were positioned them in. After every absorbance reading for the cuvettes, the cuvettes were located in another spot in front of the light. This could have caused more light to go into one part and less to enter into another triggering our data and leads to not be a sufficient as they might have been. A source of error that took place during the first part of the lab was we didn't rub enough spinach pigments onto the filtration paper so we did not have that many pigment bands. Personally i think like we does carry enough studies for our experiment to have exact results. But maybe the next time have more the perfect time to see if more DPIP will be reduced with more time under the light. To help make the experiment more scientifically acoustics, you can avoid careless errors that we does like departing fingerprints and placing them in different spots of the light with putting on gloves and marking where in fact the cuvettes were located every time. Some further experiments could be achieved to develop my knowledge could be to see how photosynthesis occurs in photoautotroph or algae. This would be interesting because instead of discovering how photosynthesis works in chloroplasts we're able to observe how photosynthesis works in animals that can offer its food.

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