1. Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce oxygen and energy in the form of glucose. 2. The chemical equation for photosynthesis is: 6CO2 + 6H2O + sunlight → C6H12O6 + 6O2, where carbon dioxide and water are converted into glucose and oxygen. 3. The machinery of photosynthesis includes chloroplasts, which contain chlorophyll, and two photosystems that absorb light energy and generate ATP and NADPH through electron transport chains.

2. carbon dioxide
sunlight
oxygenREACTANT
FROM AIR
TO AIR OR
USED FOR
RESPIRATION
PRODUCT
1. Definition of Photosynthesis
Photo means
‘light’ and
synthesis means
‘to make’
Process in which
plants convert
carbon dioxide
and water into
sugars using
solar energy
water
glucose
photosynthesis
REACTANT
FROM SOIL
USED BY PLANT
PRODUCT
Photo means
‘light’ and
synthesis means
‘to make’
Process in which
plants convert
carbon dioxide
and water into
sugars using
solar energy

3. 2. Chemical process of photosynthesis
6H2O + 6CO2 C6H12O6 + 6O2 + 6H2O
Sun lightSun light
ChlorophyllChlorophyll

4. 3. Photosynthesis Machinery

5. a. Chloroplasts

6. b. Chlorophyll
- Absorbs red & blue light
- Reflects green light

8. 4. Mechanism of Photosynthesis
1. Happen only in
sunlight
– Hence they depend on
light.
2. Light is absorbed by
chlorophyll molecules
3. The energy generates
molecules of ATP
4. Including PS I and PS
II
a. Light (dependent)Reactionsa. Light (dependent)Reactions
1. Happen only in
sunlight
– Hence they depend on
light.
2. Light is absorbed by
chlorophyll molecules
3. The energy generates
molecules of ATP
4. Including PS I and PS
II

9. Components Inside the Thylakoid
1. PS II : absorb wavelength 680 nm. Composed
of complex antenna and chlorophyll.
2. Plastoquinon (PQ)enzyme.
3. Cytochrome b6f Complex.
4. Plastocyanin enzyme
5. PS I : absorb wavelength 700 nm. Composed
of complex antenna and chlorophyll.
6. Ferredoxin (Fd) enzyme.
7. Ferredoxin NADP Reductase.
8. ATP Synthase Complex.
1. PS II : absorb wavelength 680 nm. Composed
of complex antenna and chlorophyll.
2. Plastoquinon (PQ)enzyme.
3. Cytochrome b6f Complex.
4. Plastocyanin enzyme
5. PS I : absorb wavelength 700 nm. Composed
of complex antenna and chlorophyll.
6. Ferredoxin (Fd) enzyme.
7. Ferredoxin NADP Reductase.
8. ATP Synthase Complex.

10. The differences between PS I and PS II
Photosystem I Photosystem II
Used
4 photons
1 ADP
1 Phosphate
1 H2O
1NADP+
2 photons
1 ADP
1 Phosphate
Product
1 ATP
1 NADPH + H+
½ O2
Product
1 ATP
1 NADPH + H+
½ O2
1 ATP
Reaction
Capture energy in the
formation of ATP and
NADPH, hydrogen
transfer in dark reaction
Capture energy in the
formation of ATP
Wavelength 700 nm 680 nm

12. b. Light Independent Reactions
• Happen in sunlight, and
in the dark.
– Hence “independent of
light”
1. ATP generated by
sunlight drives the
Calvin Cycle.
2. Monosaccarides (eg.
glucose) are
manufactured in the
cycle.
3. Monosaccarides are
used to “build”
polysaccharides (eg.
Starch).
• Happen in sunlight, and
in the dark.
– Hence “independent of
light”
1. ATP generated by
sunlight drives the
Calvin Cycle.
2. Monosaccarides (eg.
glucose) are
manufactured in the
cycle.
3. Monosaccarides are
used to “build”
polysaccharides (eg.
Starch).

14. C4 Cycle
• In C4 plants, it increase photosynthetic yield two to
three times more than C3 plants.
• In C4 plants, it performs a high rate of photosynthesis
even when the stomata are nearly closed.
• It increases the adaptability of C4 plant to high
temperature and light intensity.
• It increases the rate of CO2 fixation at 25° - 30°C in
C4 plants as compared to C3 plants.
• It reduces the rate of photorespiration at 25° - 30°C.
• Example of C4 plants : rice, corn, weat, sugarcane,
etc.
• In C4 plants, it increase photosynthetic yield two to
three times more than C3 plants.
• In C4 plants, it performs a high rate of photosynthesis
even when the stomata are nearly closed.
• It increases the adaptability of C4 plant to high
temperature and light intensity.
• It increases the rate of CO2 fixation at 25° - 30°C in
C4 plants as compared to C3 plants.
• It reduces the rate of photorespiration at 25° - 30°C.
• Example of C4 plants : rice, corn, weat, sugarcane,
etc.

15. Hatch-Slack Cycle

16. The Differences Between C3 Cycle with C4 Cycle
No. C3 Cycle C4 Cycle
1. The primary CO2 acceptor is a
5C compound ribulose
biphosphate (RuBP).
The primary CO2 acceptor is a 3C
compound phosphoenol pyruvic acid
(PEP).
2. The first stable compound
formed is phosphoglyceric acid
(PGA) which contain 3C atoms.
The first stable compound formed is
a 4C Oxaloacetic acid (OAA).
3. C3 cycle is completed in only
one type of chloroplast present
in mesophyll cell.
C3 cycle is completed in to types of
chloroplast, one occurring in
mesophyll cells and other in bundle
sheath cells.
C3 cycle is completed in only
one type of chloroplast present
in mesophyll cell.
C3 cycle is completed in to types of
chloroplast, one occurring in
mesophyll cells and other in bundle
sheath cells.
4. It takes place at comparatively
low temperature.
It takes place at high temperature and
more light intensities.
5. Photorespiration occurs in C3
plants.
Photorespiration is not occurs in C4
plants.
6. The rate of photosynthesis is
comparatively lower.
The rate of photosynthesis is
comparatively higher.
7. It occurs in C3 plants which
show normal anatomy.
It occurs in C3 plants which show
Kranz anatomy.

17. 5. Factors Affecting Photosynthesis Rate
External factors
1. Light intensity
2. Carbondioxide
concentration
3. Temperature
4. Water
Internal factors
1. Chlorophyll
2. Protoplasm
3. Photosynthesis product
(photosynthate)
1. Light intensity
2. Carbondioxide
concentration
3. Temperature
4. Water
1. Chlorophyll
2. Protoplasm
3. Photosynthesis product
(photosynthate)

18. 6. Photosynthesis Experiment
Ingenhousz experiment
(1799) photosynthesis
produces Oxygen (O2)

19. Sachs experiment (1860)
“Photosynthesis
produces amilum”