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Research into Photosynthesis

Research into Photosynthesis. Photosynthesis: An Overview 8.2. Where does plant mass come from? Van Helmont: From materials they take from the soil?.

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Research into Photosynthesis

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  1. Research into Photosynthesis Photosynthesis: An Overview 8.2 Where does plant mass come from? Van Helmont: From materials they take from the soil?

  2. I took an earthen pot and in it placed 200 pounds of earth which had been dried out in an oven. This I moistened with rain water, and in it planted a shoot of willow which weighed five pounds. When five years had passed the tree which grew from it weighed 169 pounds and about three ounces. The earthen pot was wetted whenever it was necessary with rain or distilled water only. It was very large, and was sunk in the ground, and had a tin plated iron lid with many holes punched in it, which covered the edge of the pot to keep air-borne dust from mixing with the earth. I did not keep track of the weight of the leaves which fell in each of the four autumns. Finally, I dried out the earth in the pot once more, and found the same 200 pounds, less about 2 ounces. Thus, 164 pounds of wood, bark, and roots had arisen from water alone." (Howe 1965)

  3. found that plants gain most of their mass from water. thus the water in carbo “hydrate” Where does carbo come from? CO2 in the air

  4. Priestly: found that plants release oxygen • Live mint sprig experiment • Something in the air was necessary to keep the candle burning. • The mint sprig produced the “something”

  5. Ingenhousz: • Took Priestley’s experiment further. • found that plants need sunlight to make oxygen.

  6. Photosynthesis • A series of reactions that use light energy to change water and carbon dioxide into sugars and oxygen 6CO2 + 6H2O LIGHT C6H12O6 + 6O2 enzymes

  7. Light and Pigments • Photosynthesis depends on pigments (molecules that absorb some light and reflect others) • Examples: chlorophyll (reflects green) and carotene (reflects orange) • Chlorophyll reflects green light and absorbs other colors (blue-violet & red) • The absorbed wavelengths power photosynthesis • Do your clothes in the closet, in the dark, have any color?

  8. Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyll b Chlorophyll a V B G Y O R Figure 8-5 Chlorophyll Light Absorption Section 8-2

  9. The absorbed light transfers energy to electrons in the chlorophyll molecule, raising the energy levels of these electrons. Through a series of reactions this energy is eventually used to join the needed atoms together to make glucose.

  10. Photosynthesis: Reactants and Products Section 8-2 Light Energy Chloroplast CO2 + H2O Sugars + O2

  11. CO2 Sugars Figure 8-7 Photosynthesis: An Overview H2O Light Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH O2 Breakdown of where the reactants and products of photosynthesis are specifically produced and used.

  12. Major events of the two Parts of Photosynthesis • LightDependent reactions • Takes place in thylakoid membranes of chloroplast • Water is split into oxygen and hydrogen • Makes ATP & NADPH • Powered by sunlight • Calvin Cycle (light independent reactions) • Takes place in stroma of chloroplast • Carbons are bonded together in a process called carbon fixation to make carbohydrates • Powered byATP & NADPH (from the light reaction)

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