University:
Cambridge College
Course:
SCI 225W | Foundations in Biology
Academic year:

2023
Views:

474

Pages:

2
Author:

M Theodore

Evidence of photosynthesis events To prove the existence of the molecules needed and produced in photosynthesis events can be done with the following experiments. 1) Sachs' experiment proves that in photosynthesis starch is produced. a) b) c) d) Leaves that have been exposed to sunlight for a while are picked. Put the leaves in boiling water. Then the leaves are placed in hot alcohol. After that, drip it with iodine solution (lugol). The result is that the leaves will be dark blue. This proves that after glucose is formed, the results of photosynthesis are immediately converted into starch. 2) Engelmann's experiment Proving that photosynthesis requires light and chlorophyll. From the results of observations under a microscope of Spirogyra and thermo bacteria, it turns out that if a beam of light falls on the Spirogyra chloroplasts, the thermo bacteria appear to be clustered in the areas containing chloroplasts that are exposed to the light. But if the beam of light does not hit the chloroplast, then nomany thermo bacteria were found. 3) Ingenhouz's experiment Proves that photosynthesis produces O2 . a) Several stems of Hydrilla verticillata plants are inserted into the funnel. b) The funnel is placed upside down in a glass beaker filled with water (the water must be full) and attached to a supporting wire. c) The pipe is closed with a test tube filled with water upside down. d) The experimental device is placed in a place exposed to sunlightdirect. The result was that there were water bubbles in the test tube.To prove whether the gas that appears is O2 can be tested by inserting a burning stick. When a flame forms, the gas that appears is O2 . 4) Van Helmont Experiment Proving that photosynthesis produces water. a) Van Helmont placed 200 pounds of drained soil in a large pot. b) The soil is sprinkled with water and a 5 pound shoot of a willow plant is planted in it. c) The pot is inserted into the soil and covers the edges withiron plate with holes. d) For 5 years Van Helmont watered his plants with rainwater or distilled water. e) The tree was removed and weighed and it turned out to weigh 164 pounds 3 ounces (this weight does not include the weight of fallen leaves + 5 years). f) The soil was dried again and weighed, it turned out to be only heavyreduced by 2 ounces from the original weight. g) Conclusion: the increase in weight of the “willow” tree only comes fromfrom water.

Evidence of Photosynthesis Events

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