Photosynthesis
• Process plants utilise to produce their own food
• Take in: water and carbon dioxide• Produce: oxygen and glucose
(light energy)carbon dioxide + water glucose + oxygen
(chlorophyll)
(light energy)6CO2 + 6H2O C6H12O6 + 6O2
(chlorophyll)
cuticle
upper epidermis
palisade mesophyll
spongy mesophyll
air pocket
lower epidermis
guard cellstoma
phloem
xylem
cuticle
sunlight
H 2O
Light-dependent reaction: -light energy converted to chemical energy -water split into oxygen and hydrogen
H+
O2CO2
C6H12O6
Light-independent reaction: hydrogen from water and carbon dioxide react to form glucose
(light energy)6CO2 + 6H2O C6H12O6 + 6O2
(chlorophyll)
How do plants use glucose?
• Convert into cellulose for growth• Convert to other sugars to transport to other
parts of the plant• To produce oils and proteins• Convert to starch for temporary storage in the
leaf (on sunny days when photosynthesis rate is very high)
• Convert back into energy via respiration
Conditions Photosynthesis v respiration Overall result
DarkRespiration No photosynthesis
Oxygen taken in Carbon dioxide given out
Dim lightPhotosynthesis rate equals respiration rate
Neither gas is taken in or given out as each cancels the other out
Bright lightPhotosynthesis rate greater than respiration rate
Carbon dioxide taken in Oxygen given out
What determines the rate of a plant’s respiration and photosynthesis?