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Photosynthesis. autotrophs – make their own food from the sun’s energy **ALL LIFE DEPENDS ON AUTOTROPHS**. Importance of plants: foodshelterdrugsO 2 soil fertilityclean H 2 O fossil fuel wood prevent soil erosion. heterotrophs – - PowerPoint PPT Presentation
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Photosynthesis
autotrophs –
make their own food from the sun’s energy
**ALL LIFE DEPENDS ON AUTOTROPHS**
Importance of plants:food shelter drugs O2
soil fertility clean H2O fossil fuel wood prevent soil erosion
heterotrophs – cannot make their own food from the sun’s energy, they rely on autotrophs
Cells need EnergyATP = Adenosine Triphosphate
low energy bond
A—P—P—P high energy bonds
When a cell needs energy, high energy bonds are broken by an enzyme.
+ PA—P—P—P A—P—P (ATP) (ADP)
energy
Partially charged
Jan Van Helmont Planted a seed in a pot of soil (mass = 2g)
5 years later the mass of the tree was 75,000g
Where did the increase in mass come from?
His conclusion was from the
H2O = hydrate
That’s only partly correct.Most of the mass comes from CO2
Joseph Priestley
Discovered that plants
released oxygen (O2)
Photosynthesis Reaction
Photosynthesis -- plants convert sunlight (chemical energy) into sugar (carbohydrates)
photo = light
synthesis = to make
The Balanced Photosynthesis Equation
CO2 H2O C6H12O6 O2LightLight
+ +6 6 6
Visible Light SpectrumThe suns energy travels in waves
The distance between waves = wavelength
Different wavelengths of light are visible as different colors
ROY G BIVLongest wavelength = Least amount of energy
Shortest wavelength = larger amount of energy
ChloroplastsHave chlorophyll and accessory pigments that trap
different wavelengths of light
Chlorophyll – reflects GreenGreen light
Accessory pigments -- Carotenoids (Kuh-RAHT-uhn-OYDZ)
reflect YellowYellow, OrangeOrange, & RedRed light
Elodea leaf
Why do plants lookWhy do plants look Green??There is much more chlorophyll than the other pigments (the other colors are masked).
In the FallFall, chlorophyll is broken down and the accessory pigment colors are shownshown.
Why do trees lose leaves in the winter?Why do trees lose leaves in the winter?It’s difficult to absorb H2O from frozen ground so leaves drop off to save water.
8-1
As the chlorophyll in leaves decays in the Fall, the green color fades and is replaced by the oranges and reds of carotenoids
PhotosynthesisThere are two reactions to photosynthesis1.1. Light-Dependent reaction Light-Dependent reaction “ “LIGHT”LIGHT”
* only occurs in light* occurs in the thylakoid membrane
chloroplast
* photosystem II* photosystem I
* H2O & sunlight make (ATP) & release (O2)
2.2. Light-Independent reaction Light-Independent reaction (Calvin Cycle)“DARK Reaction”
* can occur in the light or dark* occurs in the stroma of the chloroplasts
* Reactant CO2
* Energy ATP (from the light-dependent reaction)
* Product C6H12O6 (glucose)
Factors Affecting Photosynthesis
Water
Temperature
Light intensity
Use the following words to fill in the drawing:
C6H12O6 - (5)
Sunlight - (4)
CO2 - (4)
H20 - (5)
O2 - (4)
PhotosynthesisSummary
Light reactionLight reaction (Location: thylakoid)Reactants Processes Products
1. 1.2. 2.
1.
2.
PhotosynthesisSummary
Light reactionLight reaction (Location: thylakoid)Reactants Processes Products
1. light 1. O2
2. H2O 2. energy (ATP)
1. Photosystem II
2. Photosystem I
