2. Contents
What is photosynthesis?
Overview
Where does photosynthesis occur?(Leaf)
Structure of leaf
Why do plants need photosynthesis?
Requirements
Photosynthesis: the chemical process
Benefits of photosynthesis
3. What is photosynthesis?
The biochemical process in which
sun light fixes carbon dioxide into
glucose in the
presence of water is
called photosynthesis.
4. Photosynthesis in Overview
• Process by which plants and other autotrophs
store the energy of sunlight into sugars.
• Requires sunlight, water, and carbon dioxide.
• Overall equation:
6 CO2 + 6 H20 + sunlight C6H12O6 + 6 O2
• Occurs in the leaves of plants in organelles called
chloroplasts.
6. Leaf Structure
• Most photosynthesis occurs in the palisade layer.
• Gas exchange of CO2 and O2 occurs at openings
called stomata surrounded by guard cells on the
lower leaf surface.
Palisade
Spongy
7. Chloroplast Structure
• Inner membrane
called the thylakoid
membrane.
• Thickened regions
called thylakoids. A
stack of thylakoids
is called a granum.
(Plural – grana)
• Stroma is a liquid
surrounding the
thylakoids.
8. Pigments
• Chlorophyll A is the most important
photosynthetic pigment.
• Other pigments called antenna or accessory
pigments are also present in the leaf.
– Chlorophyll B
– Carotenoids (orange / red)
– Xanthophylls (yellow / brown)
• These pigments are embedded in the
membranes of the chloroplast in groups called
photosystems.
9.
10. Why do plants need
photosynthesis?
• Glucose is the food for the plant. It gives
the plant energy to grow.
• They do photosynthesis to gain energy.
11. Requirements for
photosynthesis to occur.
• Light
• Carbon Dioxide
• Water
• But the most important among these is
sunlight
12. Photosynthesis: The Chemical Process
• Photosynthesis is a chemical process.
• It occurs in two main phases.
– Light reactions
– Dark reactions (the Calvin Cycle)
13. Light Reactions
• Light-dependent reactions occur on the
thylakoid membranes.
– Light and water are required for this
process.
– Light reactions are the “photo” part of
photosynthesis.
– Light is absorbed by pigments and is
transformed into ATP and NADPH
molecules
14. Dark Reactions
• Dark reactions (light-independent) occur in the
stroma.
– Dark reactions are the synthesis parts of
photosynthesis
– Trapped energy by pigments is converted
into chemical ennergy
– Carbon dioxide is “fixed” into glucose
– ATP and NADPH molecules created during
the reaction is responsible for production of
this glucose
15. EQUATION FOR
PHOTOSYNTHESIS
WATER OXYGEN
6CO2 + 6H2O + ENERGY C6H12O6 +
6O2
GLUCOSE
CARBON
DIOXIDE
16. How much glucose does a plant
make?
• Plants make enough glucose to be used
during the night and on cloudy days when
they don’t get sunlight
• The extra glucose is stored in the
plant’s leaves and other parts.
17. Advantages
Basic source of energy for all livings
Production of oxygen
Healthy environment
Lessen global warming
18. PHOTOSYNTHESIS AND
LIFE
• During the process of photosynthesis,
oxygen is produced. We use this oxygen
to breathe.
19. photosynthesis and
respiration
SUN
RADIANT
ENERGY
PHOTOSYNTHESIS RESPIRATION CELL
ACTIVITIES
GLUCOSE ATP(ENERGY)
