PHOTOSYNTHESIS Source of usable energy for living things

Photosynthesis It is the conversion of solar energy to chemical energy in a form that can be utilized by living organisms. It is the conversion of solar energy to chemical energy in a form that can be utilized by living organisms. 2 steps 2 steps Light reaction - Light Dependent reaction Light reaction - Light Dependent reaction Calvin cycle - Light Independent reaction Calvin cycle - Light Independent reaction occurs in the light as well as the dark occurs in the light as well as the dark

What’s the Ultimate energy source? The sun is ultimate energy source for virtually ALL life on earth. The sun is ultimate energy source for virtually ALL life on earth. Plants and Cyanobacteria generate their own food by converting SOLAR energy to the stored energy of glucose (food). Plants and Cyanobacteria generate their own food by converting SOLAR energy to the stored energy of glucose (food). Plants and animals must then convert that food to an energy form useable at the cellular level. Plants and animals must then convert that food to an energy form useable at the cellular level.

Equation for Photosynthesis 6CO H 2 O + light -----> C 6 H 12 O 6 + 6O 2 INPUTSOUTPUTS Where does this reaction occur?

Equation for Cellular Respiration Look carefully at this equation. What equation does it appear to be similar? Look carefully at this equation. What equation does it appear to be similar? C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + Energy (ATPs) C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + Energy (ATPs) INPUTSOUTPUTS Where does this reaction occur?

Where do these inputs come from? Energy (light) comes from the sun (or some other artificial light source. Energy (light) comes from the sun (or some other artificial light source. Water comes from the soil into the plant roots & through the plant to the leaves. Water comes from the soil into the plant roots & through the plant to the leaves. Carbon Dioxide comes from the air and enters the leaves through stomata. Carbon Dioxide comes from the air and enters the leaves through stomata.

Site of Photosynthesis

Chloroplast

Harvesting of Light by Photosystems (chlorophyll acts as a solar collector)

Light Dependent Reaction Light strikes chloroplasts of a leaf cell Light strikes chloroplasts of a leaf cell Energy from light energizes chlorophyll Energy from light energizes chlorophyll Energized chlorophyll splits a water molecule, giving off the oxygen as a gas (waste) and capturing the hydrogens to use later. Energized chlorophyll splits a water molecule, giving off the oxygen as a gas (waste) and capturing the hydrogens to use later. This is the place where you’ve learned that plants give off oxygen!! This is the place where you’ve learned that plants give off oxygen!!

Photosynthesis Summary

Another summary

Yet another

Calvin Cycle (Light Independent Reaction) The fixation of carbon dioxide from atmosphere to make sugar (storing carbon) The fixation of carbon dioxide from atmosphere to make sugar (storing carbon) Light is NOT necessary for this reaction- it takes place both during the day and at night Light is NOT necessary for this reaction- it takes place both during the day and at night Combines CO 2 with other carbon containing compounds form to sugar - Glucose (6 carbons) Combines CO 2 with other carbon containing compounds form to sugar - Glucose (6 carbons) When you learned that plants take in CO 2 When you learned that plants take in CO 2 (carbon dioxide) this is where its used.

Glucose molecules

What kinds of light are involved?

Pigments 1. Chlorophyll is a pigment. It absorbs red and blue light, and transmits green light 2. Carotenoids absorb violet and blue light 3. Xanthophyls absorb yellow and orange light.

Phenol Red Indicator solution for Carbon dioxide Indicator solution for Carbon dioxide Turns red in low CO 2 Turns red in low CO 2 Turns yellow in high CO 2 Turns yellow in high CO 2

Chromatography Pigments have different rates of flow on filter paper Pigments have different rates of flow on filter paper Petroleum Ether is the solvent used to carry the pigment Petroleum Ether is the solvent used to carry the pigment Heavier pigments travel least distance Heavier pigments travel least distance Light weight pigments travel farthest Light weight pigments travel farthest

IIIIIIIIIIIII ORANGE……... CAROTENE IIIIIIIIIIIII YELLOW...XANTHOPHYLL IIIIIIIIIIIII LIGHT GREEN....CHLOR. A IIIIIIIIIIIII DARKGREEN…...CHLOR. B IIIIIIIIIIIII RED………..ANTHOCYANIN ChromatographyChromatography

Resources for photosynthesis BIOBK/BioBookPS.html BIOBK/BioBookPS.html