1. Ch 8 Energy From Sunlight

2. 8.1.2.3 Photosynthesis uses light energy to make food
Where?
Chloroplasts
Grana
Thylakoid

3. Structure of Leaf and Chloroplast
Mesophyll is leaf layer
Stomata (stoma)
CO2 in
O2 out
Veins
Carry H2O and nutrients
Chloroplast in the mesophyll

4. Structure of Chloroplast cont’
Stroma
Thick fluid that rxns occur in
Photosynthesis takes place in the chloroplast
Usually in leaves
Chlorophyll
Chemical that gives green color; uses light in photosynthesis
Light hits plant – 3 things:
Thylakoids (form stacks)
Stacks of thylakoids (grana/granum) that rxns occur in
Absorb

5. Overview of Photosynthesis
Chloroplast use e-, CO2 and H+
Produce sugar
Opposite of cellular respiration
(Glucose + O2  CO2 + H2O + “energy”)
e- are boosted “uphill”
Sunlight energy
CO2 + H2O  C6H12O6 + O2
6CO2 + 6H2O  C6H12O6 + 6O2
LIGHT

6. Light Reactions Chlorophyll in grana capture light Remove e- from H2O
H+ used
O2 is “waste product”
e- and H+ used to make NADPH
Chloroplast generate ATP
Light energy stored as:
NADPH and ATP
Convert light energy to chemical energy

7. Calvin Cycle ATP made in L.R. provides energy
Enzymes needed are in stroma
Can complete in the dark
Does not require light to begin
Makes sugar from CO2, H+ and e- (from NADPH)

8. 8.4 Photosynthesis has a global impact
Carbon Cycle
C moves from inorganic to organic compounds and back

9. Photosynthesis and Global Climate
Key molecule of Carbon cycle:
CO2
Most organisms (including plants) give off some CO2
Plants go through cellular respiration!!
CO2 traps heat in
Greenhouse effect
About 10° C warmer

10. Photosynthesis and Global Climate cont’
Prior to ~1900 CO2 made up 300 ppm of atmosphere
Now 360 ppm
Pg 173
Issues to consider…
Global Warming
Deforestation
Fossil Fuels
Alternative Fuel
Alternative Transportation

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