Bio 1 lab report #2 PDF

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Professor Rossi SCB 201 Lab 11/19/19

Lab Report 2 Abstract Autotrophs are organism that can synthase carbohydrates from CO2 using sunlight as their energy source whil heterotrophs obtain their energy by consuming other life form; they depend on autotrophs for their carbohydrates. Photosynthesis is the process by which autotrophs carbohydrates by breaking down carbohydrates to release energy that is used to power all the cell’s activities. Chloroplasts in the plant leaves harness energy from sunlight and turns it into chemical energy. Photosynthesis has two linked process, which the light reaction and the dark reaction sometimes referred to as the Calvin Cycle. the light reaction happens when light energy is absorbed by chlorophyll and other photosynthetic pigments then converted into chemical energy. The Calvin Cycle takes place in the presence of light but does not directly require it. During the Calvin cycle carbon dioxide from the atmosphere acts as the source of the new carbon atoms needed for the synthesis of the new carbohydrates most likely; glucose. The formula for photosynthesis is 6CO2 + 6H20 + (energy) → C6H12O6 + 6O2 +6H2O.

Introduction Organism can be divided into two different categories depending on how they obtain nutrition: Autotrophs and Heterotrophs. The two experiments tested today were Photosynthetic pigments (experiment one) and the separation of plant pigments (experiment two). The experiment photosynthetic pigments show the difference in pigmentations of the leaves from both the light reaction plant and the dark reaction plant. In experiment two the separation of plant pigments we used paper chromatography to separate the pigment molecules found in the leaves. The most soluble pigments went into the solution and quickly and began to migrate upwards.

Methods and Materials For the first experiment (photosynthetic pigments) the materials needed were; one 150mL breaker, two 250mL, one 450mL, dH2O, one hot plate, ethanol, two petri dish, one leaf from the light reaction, one leaf from the dark reaction, tweezers, tap water and Lugol’s solution. Firstly, my group and I marked one breaker E for ethanol and another dH2O than placed 150mL of dH2O in its matching beaker then placed the water on the hot plate to boil. We then filled 25mL of tap water into a 250mL beaker and then 75ml of the 95% ethanol into its matching breaker then placed E beaker into the 250mL containing 25mL of water and then placed it to boil on the hot plate. Afterwards we marked the petri dish one L for light reaction leaf and the other D for the dark reaction leaf then placed the light reaction into the boiling water for one-minute white

kills the plants cells and breaks open their membranes. After the minute we removed it using tweezers and placed it into the ethanol which removes the pigment from the leaf and left it there until the leaf turned white then removed it and placed it into its matching petri dish. For the dark reaction we did the same steps starting from boiling it in water for a minute then placing it in ethanol until it turns then placing it into its matching petri dish. Afterwards we filled the dish we Lugol’s solution (solution used to test for starch) and left it the soak for two to three minutes then rinsed of the leaves and the dish using tap water then returned each dish to its dish then used the tweezers to spread the leaves flat then added water into each petri. We lastly observed the staining pattern of each leaf to see if starch was present or not. For the second experiment (separation of plant pigment) the materials needed were; chromatography paper, a capillary tube, a chromatography chamber containing the solvent, ruler and a pencil. First, we marked a line two centimeters from the edge of the chromatography paper using a ruler and pencil then used a capillary tube and draw a line of pigment slight above the pencil line across the paper slightly then waited for it to dry and repeated it five times. After the fifth time drying, we then placed the paper into the chamber only holding it by the edges. We then observed the solvent move upwards but not letting it touch the top of the paper we removed it when it was about 1 cm from the top of the paper and drew a pencil line to mark the leading edge of the solvent before it evaporated. Lastly, we numbered each band of color with lowest band being one.

Results For the first experiment the leaf from light reaction plant was more stained by the Lugol’s solution.

For the second experiment the results or shown in the table below in table 1. Table 1 Band #

Band color

Pigment

1 2

Medium green Neon green

chlorophyll b chlorophyll a

Distance traveled 2.0 cm 3.0 cm

Rf 0.4 cm 0.6 cm

3 4

Light yellow yellow

xanthophyll carotene

4.0 cm 5.0 cm

0.8 cm 1.0 cm

Discussion For the first experiment (photosynthetic pigments), the leaf from light reaction showed to be stained more compared to the leaf from the dark reaction. Because plants that undergo photosynthesis in the light reaction produces more carbohydrates therefore there is more starch present in the leaf from the light reaction than there is in the dark reaction. In the second experiment (separation of plant pigments), there were four bands of color that were separated. The pigments that were obvious in the extract were chlorophyll b and chlorophyll a because they were the first two pigments that were separated on the chromatography paper. We determined the pigment for each, and we measured the Rf for each band # by taking the distance the pigment travel and dividing it by the distance the solvent front traveled which was 5cm....