1 Photosynthesis Understanding Energy Transformations

Early Investigations of Photosynthesis Jan van Helmont Joseph Priestly Jan Ingenhousz designed an experiment to determine how plants gain mass discovered that a lit candle placed in an upside down jar with a live plant would keep burning discovered plants would produce oxygen only when exposed to sunlight 2

3 Van HelmontPriestley Ingenhousz

Autotrophs What is an autotrotroph? What is an autotrotroph? A plant or other type of organism able to use energy from the sun or chemicals to produce foodA plant or other type of organism able to use energy from the sun or chemicals to produce food 4

Photosynthesis Define photosynthesis:Define photosynthesis: Examples of high-energy carbs:Examples of high-energy carbs: the use of light Energy to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydratesthe use of light Energy to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydrates Sugars and StarchesSugars and Starches 5

Energy Forms of energy:Forms of energy: Energy can be:Energy can be: Energy can be stored:Energy can be stored: light, heat, electrical, chemical & mechanicallight, heat, electrical, chemical & mechanical changed from one form to anotherchanged from one form to another in chemical bonds & then released laterin chemical bonds & then released later 6

Energy What is sunlight? What does sunlight contain? What is this called? Wavelengths of light energy A mixture Of wavelengths of different colors The visible spectrum 7

The Chloroplast What is the first step in photosynthesis? What organelle does this? Light energy must be captured The chloroplast 8

The Chloroplast What are pigments? What is chlorophyll? Light-absorbing molecules The primary light-absorbing pigment in autotrophs 9

The Chloroplast Chlorophyll a absorbs: Chlorophyll b absorbs: Accessory pigments absorb: Green wavelengths are reflected so: Red and violet wavelengthsRed and violet wavelengths Blue wavelengthsBlue wavelengths Orange, yellow and indigo wavelengthsOrange, yellow and indigo wavelengths This is why leaves are greenThis is why leaves are green 10

The Chloroplast Outer structure of a chloroplast: Inner structure of chloroplast: Green sac with a double membrane Found in mesophyll of leaf Grana - stacks of disks called thylakoids Stroma - fluid that surrounds grana 11

The Chloroplast What does the chloroplast mix with light energy? How is H 2 O supplied? How is CO 2 supplied? What controls opening of guard cells? Water and carbon dioxide Carried by xylem Diffuses through stomata Osmotic pressure 12

Photosynthesis Overview What is the 1 st stage?What is the 1 st stage? Where does it take place?Where does it take place? What happens?What happens? What is released through the stomata?What is released through the stomata? Light Dependent ReactionsLight Dependent Reactions In the granaIn the grana Light energy breaks the bonds in H 2 O moleculesLight energy breaks the bonds in H 2 O molecules Oxygen gas (O 2 )Oxygen gas (O 2 ) 13

Photosynthesis Overview What is the 2 nd stage?What is the 2 nd stage? Where does it take place?Where does it take place? What happens?What happens? What is produced?What is produced? Light Independent Reactions or The Calvin CycleLight Independent Reactions or The Calvin Cycle In the stromaIn the stroma CO 2 molecules bond with Hydrogen atomsCO 2 molecules bond with Hydrogen atoms Glucose - C 6 H 12 O 6Glucose - C 6 H 12 O 6 Oxygen gas 14

15 The Photosynthesis Equation 6H 2 O + 6CO 2 C 6 H 12 O 6 + 6O 2 Light Energy

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17 What Factors Affect the Rate of Photosynthesis? Amount of available waterAmount of available water TemperatureTemperature Amount of available light energyAmount of available light energy

Energy Flows and Cycles of Matter What is the Law of Conservation? What happens to the matter & energy? Neither matter nor energy are created or destroyed They are transferred and transformed through chemical processes 18

The Carbon Cycle What is carbon? Where is CO 2 found? How does CO 2 get there? One of the most abundant elements on Earth As a gas in the air and dissolved gas in bodies of water Cellular respiration and burning of fossil fuels 19

The Carbon Cycle How is carbon brought into the food web? How does carbon move through food web? Taken in as CO 2 & converted to glucose by producers Transferred to the tissues of consumers that eat producers and/or other consumers 20

The Oxygen Cycle Facts about Oxygen: 1.Waste gas produced when autotrophs do photosynthesis 2.Used by organisms that do some type of cellular respiration 3.Found in all biomolecules 4.Excess O bonds with H or C (CO 2 & H 2 O) 21