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Regents Biology
2006-2007
Photosynthesis:
Life from Light and Air
Regents Biology
2006-2007
Energy needs of life
 All life needs a constant input of energy

Animals = Heterotrophs
 get their energy from “eating others”
 eat food = other organisms = organic molecules
 make energy through respiration

Plants = Autotrophs
 get their energy from “self”
 get their energy from sunlight
 build organic molecules (food) from CO2
 make energy through photosynthesis
Regents Biology
Regents Biology
Photosynthesis
carbon + water + energy  glucose + oxygen
dioxide
6CO2 + 6H2O + light  C6H12O6 + 6O2
energy
This is the equation you are used to
seeing, but this is not the whole story…
Regents Biology
How do plants live?
 Photosynthesis

Energy building reactions
 collect sun energy
 make ATP

Sugar building reactions
 use ATP for energy
 use CO2 as carbon for new sugars
 build sugars
 glucose, cellulose, starch
 build all other organic molecules
 proteins, lipids, carbohydrates, DNA
 store energy for future use
 starch in seeds & roots
Regents Biology
Photosynthesis
 Actually 2 separate reactions

Energy building
Energy
building
reactions
 use sunlight
 make energy (ATP)

sun
Sugar building
 use ATP
Sugar
building
reactions
 use CO2
 make sugars (C6H12O6)
Regents Biology
ATP
ADP
CO2
sugar
Chloroplasts
Leaf
Leaf
absorb
sunlight & CO2
CO2
Chloroplasts
Chloroplast
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Chloroplasts
contain
Chlorophyll
make
energy & sugar
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Energy Building Reactions
H2O +
H2O
 makes ATP energy
 releases oxygen
as a waste product
sunlight
Energy Building
Reactions
ATP
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O2
light  ATP + O
2
energy
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Sugar Building Reactions
CO2 + ATP  C6H12O6 + ADP
CO2
ADP
Sugar
Building
Reactions
ATP
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sugars
C6H12O6
 builds sugars
 uses ATP
 cycles ADP
back to make
more ATP
Putting it all together
CO2 + H2O + light  C6H12O6 +
energy
H2O
CO2
sunlight
ADP
Sugar
Building
Reactions
Energy
Building
Reactions
ATP
Regents Biology
O2
sugars
C6H12O6
O2
Plants make both:
 ATP
 sugars
So what does a plant
need?
 Bring In
leaves
CO2
 H2O
 light

 Let Out

O2
 Move Around

shoot
roots
sugars
6CO2 + 6H2O + light  C6H12O6 + 6O2
Regents Biology
energy
Regents Biology
Leaf Structure
cuticle
epidermis
xylem (water)
phloem (sugar)
palisades
layer
spongy
layer
O2 H O
2
 gases in & out
 water out
O2
Regents
Biology
 transpiration
CO2
stomate
H 2O
CO2
guard
cell
Stomates
 Function of stomates
CO2 in
 O2 out
 H2O out

guard cell
stomate
Regents Biology
Regents Biology
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Xylem
carry water up from roots
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Phloem: food-conducting cells
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 carry sugars around the
plant wherever they are
needed
 new leaves
 fruit
 seeds
Putting it all together
 Making a living…

sunlight
 leaves = solar collectors
 photosynthesis

gases: CO2 in & O2 out
 stomates = gases in & out

H2O
 roots take in water from soil
 pulled up by leaf evaporation

nutrients
 roots take in from soil
Regents Biology
Regents Biology
How are they connected?
Respiration
glucose + oxygen  carbon + water + energy
dioxide
C6H12O6 +
6O2
 6CO2 + 6H2O + ATP
Photosynthesis
carbon + water + energy  glucose + oxygen
dioxide
6CO2 + 6H2O + light  C6H12O6 + 6O2
energy
Regents Biology
Regents Biology
Energy cycle
sun
Photosynthesis
plants
CO2
glucose
H2O
animals, plants
Cellular Respiration
The Great Circle
of Life!
Where’s Mufasa?
Regents Biology
ATP
O2
Regents Biology
The poetic perspective
 All of the solid material of every plant
was built out of thin air
 All of the solid material of every animal
was built from plant material
air
Regents Biology
Then all the cats, dogs,
mice, people & elephants…
are really strands of air woven
together by sunlight!
sun