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Lab Report Photosynthesis

Decent Essays

I. Introduction
Photosynthesis is the process by which plants use light to synthesize food from H2O and CO2 within the thylakoid and the stroma of the cells. In order for photosynthesis to occur, light must be present. Light reactions occur within the thylakoids of the chloroplasts by absorbing light and H2O and producing oxygen gas, ATP, or Adenosine triphosphate, and NADPH, or nicotinamide adenine dinucleotide phosphate. The oxygen gas is released back into the atmosphere while ATP and NADPH are inputs of the Calvin Cycle within the stroma. The Calvin Cycle uses these two molecules, in addition to carbon dioxide gas, to produce ADP, or Adenosine diphosphate, NADP+, and glucose molecules. Photosynthesis is represented by the following equation: …show more content…

It showed that there was no CO2 present for the input of the photosynthesis reaction so the oxygen given off must have come from the H2O. This means that since photosynthetic reactions occurred without CO2 present, light reactions did not necessarily need CO2 to occur. The reaction only needed water and light. Oxidation-reduction reactions are initiated by light and are significant in photosynthetic reactions. When light reactions occur, electrons reduce NADP+ by adding an H+ ion, which forms NADPH. DPIP is a blue dye that is used to detect photosynthetic reaction rates by intercepting these electrons that flow during photosynthesis. The transition from blue dye to colorless signifies that photosynthesis is occurring. This reaction is represented by the following …show more content…

The leaf with the highest rate of photosynthesis was the darkest leaf, the purple cabbage. The leaf with the lowest rate of photosynthesis was the lightest leaf, the iceberg lettuce. We can conclude that the rate of photosynthesis was much higher in the purple cabbage because darker leaves contain more chloroplasts. Therefore, photosynthesis occurs much more quickly. Notably, these results support the stated hypothesis. An error that might have affected the data as a whole was the fact that the calculated rate of photosynthesis for the iceberg lettuce was negative. In addition to this, a few of the other percentages decreased as time passed. This means that the chloroplasts would have been going through cellular respiration. This inconsistency might have transpired from a mechanical error within the spectrophotometer. The control tubes, the “boiled” and “dark” tubes, of all 3 leaves were necessary in order to determine if the chloroplasts were the organelles of the cell that were causing one leaf to photosynthesize quicker than another because it was imperative for the chloroplasts to be exposed to light and temperatures that would not denature them. Therefore, we are able to conclude that the chloroplasts located within the leaves were the organelles that were causing the varying rates of photosynthesis in this

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