Identifying the Properties of Photosynthesis

Photosynthesis is: This conversion of the Sun’s energy into chemical energy is the single most important reaction on earth, and could be called This conversion of the Sun’s energy into chemical energy is the single most important reaction on earth, and could be called THE REACTION OF LIFE. THE REACTION OF LIFE.

Photosynthesis One of the main differences between plants and animals is the ability of plants to manufacture their own food.

Photosynthesis - Respiration Comparison Photosynthesis Photosynthesis Occurs only in green plants Occurs only in green plants Occurs only in green plant cells Occurs only in green plant cells Proceeds only in light Proceeds only in light Food is made Food is made Increases dry weight Increases dry weight CO 2, H 2 O are used CO 2, H 2 O are used Produces sugars and O 2 Produces sugars and O 2 Stores energy in sugar Stores energy in sugar ATP & NADPH produced ATP & NADPH produced ATP and NADPH used in sugar synthesis ATP and NADPH used in sugar synthesis Respiration Occurs in all plants and animals Occurs in all living cells Proceeds in light and darkness Food is used Decreases dry weight Sugar and O 2 are used Produces CO 2 and H 2 O Releases energy ATP produced ATP and NADPH used for many reactions

Photosynthesis In Photosynthesis Light energy is captured by chlorophyll contained in green tissue of plants, mainly the leaves, In Photosynthesis Light energy is captured by chlorophyll contained in green tissue of plants, mainly the leaves, And is used to convert carbon dioxide CO 2 from the air and water H 2 O from the soil & atmosphere into carbohydrates C 6 H 12 O 6 which are stored in the plant for future use. And is used to convert carbon dioxide CO 2 from the air and water H 2 O from the soil & atmosphere into carbohydrates C 6 H 12 O 6 which are stored in the plant for future use.

Photosynthesis occurs in the chlorophyll molecule of the chloroplasts in the leaves of green plants and photosynthetic bacteria

Plant Cell with Chloroplast

Algae Cell with Chloroplasts.

Photosynthesis The carbohydrate is stored inside cell vacuoles until use in several metabolic processes: The carbohydrate is stored inside cell vacuoles until use in several metabolic processes: Glycolysis - glucose to pyruvic acid Glycolysis - glucose to pyruvic acid Respiratory metabolism Respiratory metabolism Metabolic maintenance - growth of plant cells and tissues Metabolic maintenance - growth of plant cells and tissues

Photosynthesis Photosynthesis takes place in the CHLOROPLAST of the cells.

The Structure of the Chloroplasts

Plant Cell

The Leaf & Photosynthesis Green Plant Light Energy

Requirements for Photosynthesis 1. Healthy, living, green plant 1. Healthy, living, green plant 2. Light 2. Light 3. Carbon Dioxide (CO 2 ) 3. Carbon Dioxide (CO 2 ) 4. Water (H 2 O) 4. Water (H 2 O)

Factors Affecting Photosynthesis

1. Light Quality 1. Light Quality 2. Light Intensity 2. Light Intensity 3. Light Duration 3. Light Duration 4. Carbon Dioxide Concentration 4. Carbon Dioxide Concentration 5. Temperature 5. Temperature 6. Water Availability 6. Water Availability

Factors Affecting Photosynthesis 1. Light Quality 1. Light Quality Light is required for the process of photosynthesis Light is required for the process of photosynthesis Chloroplasts contain chlorophyll capable of intercepting light and converting electromagnetic energy to chemical energy. Chloroplasts contain chlorophyll capable of intercepting light and converting electromagnetic energy to chemical energy. Chlorophyll molecules absorb mostly red (700 nm) and blue (450 nm) light and reflect green light (that is why plants look green to the human eye). Chlorophyll molecules absorb mostly red (700 nm) and blue (450 nm) light and reflect green light (that is why plants look green to the human eye).

Light Waves & Photosynthesis

Light Spectrum

Factors Affecting Photosynthesis 2. Light Intensity 2. Light Intensity Influences the rate of photosynthesis. Influences the rate of photosynthesis. Some species require high light intensity Some species require high light intensity “Sun-loving plants” “Sun-loving plants” Corn, turf Corn, turf Some species do not require high light intensity Some species do not require high light intensity “Shade-loving plants” “Shade-loving plants” Forest floors, house ornamentals Forest floors, house ornamentals

Factors affecting Photosynthesis 3. Light Duration 3. Light Duration A plants photosynthetic production is directly proportional to the length of day. A plants photosynthetic production is directly proportional to the length of day. The longer the leaves receive light, the longer they photosynthesize and the faster the plant grows. The longer the leaves receive light, the longer they photosynthesize and the faster the plant grows.

Factors Affecting Photosynthesis 4. CO 2 Carbon Dioxide Concentration 4. CO 2 Carbon Dioxide Concentration Concentration of Carbon Dioxide in the air surrounding the leaves affects photosynthesis. Concentration of Carbon Dioxide in the air surrounding the leaves affects photosynthesis. Normal atmospheric concentrations of CO 2 are 0.03% and O 2 are 21%. Normal atmospheric concentrations of CO 2 are 0.03% and O 2 are 21%. Experiments have shown increases in atmospheric CO 2 can increase photosynthesis rates. Experiments have shown increases in atmospheric CO 2 can increase photosynthesis rates. Increasing CO 2 to 0.1% will double the photosynthesis rate in wheat, rice, and some vegetables. Increasing CO 2 to 0.1% will double the photosynthesis rate in wheat, rice, and some vegetables.

The exchange of oxygen & carbon dioxide in the leaf occurs through pores called stoma

Factors Affecting Photosynthesis 5. Temperature 5. Temperature As a general rule, if light is not limiting, photosynthesis rates will double for each 18 o F increase in temperature As a general rule, if light is not limiting, photosynthesis rates will double for each 18 o F increase in temperature Excessively high temperatures (>100 o ) will reduce photosynthesis by causing stoma closure (no uptake of CO 2 ) Excessively high temperatures (>100 o ) will reduce photosynthesis by causing stoma closure (no uptake of CO 2 ) o F is optimum o F is optimum

Factors Affecting Photosynthesis 6. Water Availability 6. Water Availability Excessive soil moisture reduces root respiration and limits photosynthesis in leaves Excessive soil moisture reduces root respiration and limits photosynthesis in leaves Water stress conditions (low soil moisture; hot, drying winds) Water stress conditions (low soil moisture; hot, drying winds) Plants transpire water faster than it can be absorbed through roots Plants transpire water faster than it can be absorbed through roots Leaves wilt and gas exchange (CO 2 and O 2 ) is restricted thus decreasing photosynthesis rates Leaves wilt and gas exchange (CO 2 and O 2 ) is restricted thus decreasing photosynthesis rates

Photosynthesis - Equation General Reaction Green Plant Light Energy Green Plant Light Energy

Discussing the Equation Six molecules of carbon dioxide react with Six molecules of carbon dioxide react with twelve molecules of water twelve molecules of water in the presence of light and a green plant in the presence of light and a green plant to produce: to produce: one molecule of glucose (carbohydrate) one molecule of glucose (carbohydrate) six molecules of water and six molecules of water and six molecule of oxygen six molecule of oxygen Green Plant Light Energy

Products of Photosynthesis Carbohydrates Carbohydrates Water Water Oxygen Oxygen Green Plant Light Energy

Photosynthesis in a Plant

The Chemistry of Photosynthesis The process of photosynthesis is stated in simple equations, but the total process is extremely complex. The process of photosynthesis is stated in simple equations, but the total process is extremely complex. The overall process is separated into two parts: The overall process is separated into two parts: Light Reactions (Hill Reaction) Light Reactions (Hill Reaction) Dark Reactions (Calvin Cycle) Dark Reactions (Calvin Cycle)

The Light and Dark Reactions of Photosynthesis.

Light Reaction (Hill Reaction) In the Light Reaction, energy in the form of light received by chlorophyll is used to: In the Light Reaction, energy in the form of light received by chlorophyll is used to: 1.) Reduce (NADP + ) to NADPH. 1.) Reduce (NADP + ) to NADPH. 2.) Provide chemical energy through the production of adenosine triphosphate (ATP) from adenosine diphosphate (ADP). 2.) Provide chemical energy through the production of adenosine triphosphate (ATP) from adenosine diphosphate (ADP). 3.) The water molecule is split to produce O 2 and H + 3.) The water molecule is split to produce O 2 and H + Green Plant Light Energy

The Z-Scheme of Photosynthesis A chlorophyll photo-active center (PSII) in the granum is activated by light and splits the water molecule into O 2 and H +. A chlorophyll photo-active center (PSII) in the granum is activated by light and splits the water molecule into O 2 and H +. As the Energy is passed downhill, ATP is formed. ATP is energy. As the Energy is passed downhill, ATP is formed. ATP is energy. A second photo-active center (PSI) receives light, and releases energy, delivering electrons to form NADPH. A second photo-active center (PSI) receives light, and releases energy, delivering electrons to form NADPH.

Light Reaction (Z-Scheme) Light 2H 2 O  4H + + O 2 + 2e - (Photolysis) Photosystem II Photosystem I P 680 P e - Electron Acceptors Electron Transport System Increasing Energy Level Electron Transport System 2 e - NADP + H+H+ NADPH

Z-Scheme - Light Reaction

Z-Scheme of the Light Reaction

Light Reaction - Hill Reaction Notes: 1. Light energy is received by chlorophyll and used to reduce NADP to NADPH.. 1. Light energy is received by chlorophyll and used to reduce NADP to NADPH.. 2. Production of ATP 2. Production of ATP 3. The water molecule is split to produce Oxygen. 3. The water molecule is split to produce Oxygen. Green Plant Light Energy

Light Reaction - Hill Reaction Notes: The Hill Reaction occurs in the Granum of the Chloroplast. The Hill Reaction occurs in the Granum of the Chloroplast. Requires Light Requires Light

Light Reaction Hill Reaction Dark Reaction Calvin Cycle

The Light Reactions of Photosynthesis stop when the sun goes down.

The Dark Reaction is known as the Calvin Cycle

Dark Reacton - Calvin Cycle The Calvin Cycle is the Carbon-Fixing Cycle of Photosynthesis. It does not require light. The Calvin Cycle is the Carbon-Fixing Cycle of Photosynthesis. It does not require light. It may proceed in light or dark. It may proceed in light or dark.

Dark Reaction - Calvin Cycle The Calvin Cycle takes place in the stroma of the chloroplast. The Calvin Cycle takes place in the stroma of the chloroplast.

Dark Reaction - Calvin Cycle The Calvin Cycle uses NADPH and ATP from the Light Reaction to convert Carbon Dioxide to a six Carbon Sugar Molecule. The Calvin Cycle uses NADPH and ATP from the Light Reaction to convert Carbon Dioxide to a six Carbon Sugar Molecule.

Dark Reaction - Calvin Cycle Carbon dioxide molecules from the air enter the cycle one cycle at a time, making six turns of the cycle necessary to produce one molecule of (sugar) glucose, C 6 H 12 O 6. Carbon dioxide molecules from the air enter the cycle one cycle at a time, making six turns of the cycle necessary to produce one molecule of (sugar) glucose, C 6 H 12 O 6.

Calvin Cycle

Dark Reaction (Calvin Cycle) In the Dark Reaction of Photosynthesis, In the Dark Reaction of Photosynthesis, 1. Carbon taken into the plant as CO 2 from the air accepts the energy, ATP & NADPH from light reaction. 1. Carbon taken into the plant as CO 2 from the air accepts the energy, ATP & NADPH from light reaction. 2.This energy is used to convert carbon dioxide into carbohydrates, (Glucose). 2.This energy is used to convert carbon dioxide into carbohydrates, (Glucose). Green Plant Light Energy

Calvin Cycle Notes Does not require light. Does not require light. May proceed in light or dark. May proceed in light or dark. Occurs in the Stroma of the Chloroplast. Occurs in the Stroma of the Chloroplast. Uses NADPH & ATP from the light reaction to convert CO 2 to a 6 carbon sugar. Uses NADPH & ATP from the light reaction to convert CO 2 to a 6 carbon sugar. Green Plant Light Energy

Review of Photosynthesis

Photosynthesis - Photosynthesis Photosynthesis Occurs only in green plants Occurs only in green plants Occurs only in green plant cells Occurs only in green plant cells Proceeds only in light Proceeds only in light Food is made Food is made Increases dry weight Increases dry weight CO 2, H 2 O are used CO 2, H 2 O are used Produces sugars and O 2 Produces sugars and O 2 Stores energy in sugar Stores energy in sugar ATP and NADPH are produced ATP and NADPH are produced

Photosynthesis is: The Transformation of sun’s energy (light) into useable chemical energy The Transformation of sun’s energy (light) into useable chemical energy The Reaction of Life The Reaction of Life

Requirements for Photosynthesis 1. Healthy, living, green plant 1. Healthy, living, green plant 2. Light 2. Light 3. Carbon Dioxide (CO 2 ) 3. Carbon Dioxide (CO 2 ) 4. Water (H 2 O) 4. Water (H 2 O)

Factors Affecting Photosynthesis Light Quality Light Quality Light Intensity Light Intensity Light Duration Light Duration Carbon Dioxide Carbon Dioxide Temperature Temperature Water Availability Water Availability

Photosynthesis - Equation General Reaction Green Plant Light Energy

The Chemistry of Photosynthesis The process of photosynthesis is stated in simple equations, but the total process is extremely complex. The overall process is separated into two parts: The process of photosynthesis is stated in simple equations, but the total process is extremely complex. The overall process is separated into two parts: Light Reactions (Hill Reaction) Light Reactions (Hill Reaction) Dark Reactions (Calvin Cycle) Dark Reactions (Calvin Cycle)

Hill Reaction Notes: Light energy is received by chlorophyll and used to synthesize ATP and NADPH Light energy is received by chlorophyll and used to synthesize ATP and NADPH Requires Light Requires Light Creates Oxygen Creates Oxygen Occurs in the Granum Occurs in the Granum

Calvin Cycle Notes Does not require light Does not require light May proceed in light or dark May proceed in light or dark Occurs in the Stroma Occurs in the Stroma Uses NADPH & ATP from the light reaction to convert CO 2 to a 6 carbon sugar. Uses NADPH & ATP from the light reaction to convert CO 2 to a 6 carbon sugar.