Photosynthesis (8.2)
State Standard
SB3A. Explain the cycling of energy through
the processes of photosynthesis and
respiration.
8.2 Photosynthesis
Overview
Photosynthesis traps light (solar) energy & converts it
to chemical energy in the form of carbohydrates
(food).
*Don’t forget – photosynthetic organisms must also break down
some of those carbohydrates to form ATP for themselves.
8.2 Photosynthesis
Overview cont’d
*Label the reactants & products in
the equation below
The trapped light energy is used to convert the raw
materials CO2 & H2O into carbohydrates & O2
PHOTOSYNTHESIS EQUATION
8.2 Photosynthesis
Overview cont’d
The key to absorbing light is a green pigment called
chlorophyll, found in chloroplasts.
Chloroplast Parts
Thylakoid – looks like
a pancake (flattened sac)
Granum (pl. grana) –
stack of thylakoids
Stroma – space
between grana – gellike matrix
8.2 Photosynthesis
Overview cont’d
Photosynthesis…
• requires absorption of light energy.
– broad, flat leaves increase the amount of light
that can be absorbed
• supports almost all life on Earth either directly or
indirectly.
• converts light energy to chemical energy usually in
the form of glucose (carb).
• Occurs in the chloroplasts.
Chapter 8
Cellular Energy
8.2 Photosynthesis
Overview cont’d
Photosynthesis occurs in 2 phases.
 Light-Dependent reactions
* also called light reactions
* occur in the thylakoid membrane.
* This is the photo part of photosynthesis.
 Light-Independent reactions
*also called the Calvin Cycle
* occur in the stroma
* This is the synthesis part of photosynthesis
Chapter 8
Cellular Energy
8.2 Photosynthesis
Part 1
Light Dependent Reactions
Location: Thylakoid
•Splits water molecules
•Produces power for the
Calvin Cycle
8.2 Photosynthesis
Part 1 Light Dependent
Reactions Cont’d
•
Products
–
–
–
•
ATP
NADPH (a high energy electron carrier)
Oxygen (formed from the splitting of water by light)
Where do they end up?
–
–
ATP and NADPH go on to power the next group of
reactions
Oxygen is released out of the cell and we breathe it
in.
Chapter 8
Cellular Energy
8.2 Photosynthesis
Part 2: The Calvin Cycle (Light-Independent)
Location: Stroma
 stores energy in
organic molecules
such as glucose.
• powered by the products of
the light dependent
reactions
8.2 Photosynthesis
Part 2: The Calvin Cycle (Light-Ind) cont’d
• Uses carbon dioxide (CO2) from the atmosphere &
energy from the light-dependent reactions to fuel
its processes.
• Products:
– glucose or other sugars (which are stored)
* some are used by the plant
* others are used by heterotrophs
8.2 Photosynthesis
Part 2: Calvin Cycle (Light Ind.) cont’d
8.2 Photosynthesis
Part 2: Calvin Cycle (Light Ind.) cont’d
The Calvin Cycle
is the sugar
factory!
Calvin Cycle
Chocolate Chips
Cotton Candy
Candy Cane
Coca Cola
8.2 Photosynthesis
Photosynthesis Graphic Organizer
Chapter 8
Cellular Energy
Chapter Diagnostic
Questions
At the end of the Calvin cycle, where is energy
stored?
A. NADPH
B. ATP
C. chloroplast
D. glucose
1.
2.
3.
4.
0%
A
0%
B
A
B
C
D
0%
C
0%
D
Chapter 8
Cellular Energy
8.2 Formative
Questions
Where in the plant cell does
photosynthesis take place?
1.
2.
3.
4.
0%
C
0%
B
A
0%
A
B
C
D
0%
D
A. chloroplasts
B. Golgi apparatus
C. mitochondria
D. vacuoles
Chapter 8
Cellular Energy
Chapter Assessment
Questions
Look at the following figure.
Which part of the chloroplast
is a sac-like membrane
arranged in stacks?
A. grana
B. stroma
C. thylakoids
D. Golgi apparatus
1.
2.
3.
4.
0%
D
0%
C
0%
B
A
0%
A
B
C
D
Chapter 8
Cellular Energy
Standardized Test
Practice
Which metabolic process is photosynthesis?
A
1.
2.
A
B
B
0%
B
A
0%
Chapter 8
Cellular Energy
Standardized Test
Practice
At the beginning of photosynthesis, which
molecule is split to produce oxygen (O2) as
a waste product?
1.
2.
3.
4.
0%
C
0%
B
A
0%
A
B
C
D
0%
D
A. CO2
B. H2O
C. C6H12O6
D. 3-PGA
Chapter 8
Cellular Energy
Standardized Test
Practice
Which molecule helps
provide the energy
that drives this cycle?
A. 3-PGA
B. CO2
C. NADPH
D. rubisco
1.
2.
3.
4.
0%
D
0%
C
0%
B
A
0%
A
B
C
D