Photosynthesis ularlifeandgenetics/photosynthesis/ ularlifeandgenetics/photosynthesis/

Photosynthesis Photosynthesis – the process by which plants use the energy of sunlight to convert water and carbon dioxide into oxygen and carbohydrates (GLUCOSE). Photosynthesis – the process by which plants use the energy of sunlight to convert water and carbon dioxide into oxygen and carbohydrates (GLUCOSE).

Investigating Photosynthesis Van Helmont’s Experiment Van Helmont’s Experiment 1600’s – Dutch Physician 1600’s – Dutch Physician Experimented to see if plants grew by taking nutrients out of the soil. Experimented to see if plants grew by taking nutrients out of the soil.

Investigating Photosynthesis Van Helmont concluded that most of the mass of the plant gained had come from water, because that was the only thing he had added to the pot. Van Helmont concluded that most of the mass of the plant gained had come from water, because that was the only thing he had added to the pot. This is how we discovered the water portion of photosynthesis. This is how we discovered the water portion of photosynthesis.

Investigating Photosynthesis Priestley’s Experiment Priestley’s Experiment English Minister He took and candle, placed a glass jar over it and noticed the candle went out. Something the candle needs is running out.

Investigating Photosynthesis Preistley found that if he placed a live sprig of mint under the jar and allowed a few days to pass, the candle could be re-lighted and would remain lighted for a while. The plant must be producing oxygen. Preistley found that if he placed a live sprig of mint under the jar and allowed a few days to pass, the candle could be re-lighted and would remain lighted for a while. The plant must be producing oxygen.

Investigating Photosynthesis Jan Ingenhousz Jan Ingenhousz Dutch Scientist Dutch Scientist Used Preistley’s experiment to help prove that light was needed for the plants to produce oxygen. Used Preistley’s experiment to help prove that light was needed for the plants to produce oxygen.

The Photosynthesis Equation

Light and Pigments In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll (found in chloroplasts). In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll (found in chloroplasts). Plants gather the sun’s energy with light absorbing molecules called pigments. Plants gather the sun’s energy with light absorbing molecules called pigments.

Light and Pigments Plants principal pigment is chlorophyll. Plants principal pigment is chlorophyll. There are two types of chlorophyll – chlorophyll a and chlorophyll b There are two types of chlorophyll – chlorophyll a and chlorophyll b Chlorophyll absorbs red and blue light very well, but does not absorb green light, which is why plants look green Chlorophyll absorbs red and blue light very well, but does not absorb green light, which is why plants look green

The Reactions of Photosynthesis Photosynthesis takes place inside chloroplasts. Photosynthesis takes place inside chloroplasts.

The Reactions of Photosynthesis Chloroplasts contain photosynthetic membranes called thylakoids – thylakoids are arranged in stacks known grana. Thylakoids contain clusters of chlorophyll. Chloroplasts contain photosynthetic membranes called thylakoids – thylakoids are arranged in stacks known grana. Thylakoids contain clusters of chlorophyll.

Two Stages of Photosynthesis 1. Light Dependent Reactions (light reactions) Take place inside the thylakoid membranes Take place inside the thylakoid membranes Require Light Require Light Sunlight is absorbed by chlorophyll. The energy absorbed is used to split water (H2O) into Hydrogen (H) and Oxygen (O). Sunlight is absorbed by chlorophyll. The energy absorbed is used to split water (H2O) into Hydrogen (H) and Oxygen (O).

H O H + = H + O

Two Stages of Photosynthesis The oxygen is released as a waste product. The oxygen is released as a waste product. The hydrogen is used in the light independent reactions (dark reactions) The hydrogen is used in the light independent reactions (dark reactions)

Two Stages of Photosynthesis 2. Light Independent Reactions (dark reactions) a. The hydrogen formed in the light reactions combines with carbon dioxide from the air. b. The Hydrogen and Carbon Dioxide are used to produce glucose.