1. Photosynthesis: Energy From Sunlight
Chapter 8
Photosynthesis: Energy From Sunlight
CH 8
Photo Credit: ©Stone
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2. The Photosynthesis Equation
The equation for photosynthesis is:
6CO2 + 6H2O C6H12O6 + 6O2
Light
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3. Where does photosynthesis occur?
In plants, photosynthesis takes place inside chloroplasts.
Function – convert solar energy into chemical energy
Chloroplast
Plant cells
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Inside a Chloroplast
thylakoids—saclike membranes inside the chloroplasts.
Structure – thylakoid membranes are stacked; they contain pigments such as chlorophyll
Single
thylakoid
Chloroplast
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Inside a Chloroplast
A stack of thylakoids is called a granum.
Granum
Chloroplast
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Inside a Chloroplast
The fluid that fills the chloroplast and surrounds the thylakoids is called the Stroma
Stroma
Chloroplast
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7. How do chloroplasts harvest light energy?
Chlorophyll absorbs light well in the blue-violet and red regions of the visible spectrum.
Chlorophyll does not absorb light well in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green.
Photosynthesis requires light and chlorophyll. In the graph above, notice how chlorophyll a absorbs light mostly in the blue-violet and red regions of the visible spectrum, whereas chlorophyll b absorbs light in the blue and red regions of the visible spectrum.
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8. Photosynthesis Occurs in Two Steps
The Light Reaction
Uses sunlight & H2O to make ATP and NADPH and releases O2
The Calvin Cycle
Light-independent reaction
Uses ATP, CO2 and NADPH to produce high energy sugars 8

9. The Light Reaction Takes place in the Thylakoid membrane
Also called the Electron Transport Chain.
Requires:
Light
Water
NADP+ and H+
ADP and P
Produces:
ATP
Oxygen (O2)
NADPH 9

10. The Calvin Cycle Takes place in the Stroma
Also called the “Dark Reaction”
Requires:
NADPH and ATP from light reaction
CO2
Produces:
ADP + P
NADP+
3C sugar (G3P) glucose, fatty acids, or cellulose 10

11. Light- dependent reactions
H2O
CO2
Light
NADP+
ADP + P
Light- dependent reactions
Calvin cycle
Calvin Cycle
The process of photosynthesis includes the light-dependent reactions as well as the Calvin cycle. O2
Sugars
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