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PhotosynthesisPhotosynthesis

Understanding Understanding Energy Energy TransformationsTransformations

Early Investigations of Photosynthesis 1600-1779

• 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

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Van Helmont Priestley Ingenhousz

AutotrophsAutotrophs

• What is an What is an autotrotropautotrotroph?h?

• A plant or other A plant or other type of type of organism able organism able to use energy to use energy from the sun or from the sun or chemicals to chemicals to produce foodproduce food

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PhotosynthesisPhotosynthesis• Define Define

photosynthesisphotosynthesis::

• Examples of Examples of high-energy high-energy carbs:carbs:

• the use of light the use of light Energy to convert Energy to convert Water (HWater (H220) and 0) and Carbon Dioxide Carbon Dioxide (CO(CO22) into Oxygen ) into Oxygen (O(O22) and High ) and High Energy Energy CarbohydratesCarbohydrates

• Sugars and StarchesSugars and Starches5

EnergyEnergy• Forms of Forms of

energy:energy:

• Energy can Energy can be:be:

• Energy can Energy can be stored:be stored:

• light, heat, light, heat, electrical, electrical, chemical & chemical & mechanicalmechanical

• changed from one changed from one form to anotherform to another

• in chemical bonds in chemical bonds & then released & then released laterlater

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EnergyEnergy• 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

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The Chloroplast

• What is the first step in photosynthesis?

• What organelle does this?

• Light energy must be captured

• The chloroplast

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The Chloroplast

• What are pigments?

• What is chlorophyll?

•Light-absorbing molecules

•The primary light-absorbing pigment in autotrophs

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The Chloroplast• Chlorophyll a

absorbs:• Chlorophyll b

absorbs:• Accessory

pigments absorb:

• Green wavelengths are reflected so:

• Red and violet Red and violet wavelengthswavelengths

• Blue wavelengthsBlue wavelengths

• Orange, yellow Orange, yellow and indigo and indigo wavelengthswavelengths

• This is why This is why leaves are greenleaves are green

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The ChloroplastThe 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

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The Chloroplast• What does the

chloroplast mix with light energy?

• How is H2O supplied?

• How is CO2 supplied?

• What controls opening of guard cells?

• Water and carbon dioxide

• Carried by xylem

• Diffuses through stomata

• Osmotic pressure

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Photosynthesis OverviewPhotosynthesis Overview• What is the 1What is the 1stst

stage?stage?• Where does it Where does it

take place?take place?• What happens?What happens?

• What is What is released released through the through the stomata?stomata?

• Light Dependent Light Dependent ReactionsReactions

• In the granaIn the grana

• Light energy Light energy breaks the bonds breaks the bonds in Hin H22O moleculesO molecules

• Oxygen gas (OOxygen gas (O22))

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Photosynthesis OverviewPhotosynthesis Overview

• What is the What is the 22ndnd stage? stage?

• Where does Where does it take place?it take place?

• What What happens?happens?

• What is What is produced?produced?

• Light Independent Light Independent Reactions or The Reactions or The Calvin Cycle Calvin Cycle

• In the stromaIn the stroma

• COCO22 molecules bond molecules bond with Hydrogen with Hydrogen atomsatoms

• Glucose - CGlucose - C66HH1212OO66

• Oxygen gas14

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The Photosynthesis The Photosynthesis EquationEquation6H2O + 6CO2 C6H12O6 + 6O2

Light Energy

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What Factors Affect the What Factors Affect the Rate of Photosynthesis?Rate of Photosynthesis?

•Amount of Amount of available available waterwater

• TemperatureTemperature•Amount of Amount of

available available light energylight 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

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The Carbon Cycle• What is

carbon?

• Where is CO2 found?

• How does CO2 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 fuels19

The Carbon Cycle• How is

carbon brought into the food web?

• How does carbon move through food web?

• Taken in as CO2 & converted to glucose by producers

• Transferred to the tissues of consumers that eat producers and/or other consumers

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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 (CO2 & H2O)

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