1. The process of making food
Photosynthesis
The process of making food

2. Overview: The Process That Feeds the Biosphere Photosynthesis
Is the process that converts solar energy into chemical energy

3. Plants are photoautotrophs
They use the energy of sunlight to make organic molecules from water and carbon dioxide

4. (b) Multicellular algae (c) Unicellular protist
Photosynthesis
Occurs in plants, algae, certain other protists, and some prokaryotes
These organisms use light energy to drive the
synthesis of organic molecules from carbon dioxide
and (in most cases) water. They feed not only
themselves, but the entire living world. (a) On
land, plants are the predominant producers of
food. In aquatic environments, photosynthetic
organisms include (b) multicellular algae, such
as this kelp; (c) some unicellular protists, such
as Euglena; (d) the prokaryotes called
cyanobacteria; and (e) other photosynthetic
prokaryotes, such as these purple sulfur
bacteria, which produce sulfur (spherical
globules) (c, d, e: LMs).
(a) Plants
(b) Multicellular algae
(c) Unicellular protist
10 μm
40 μm
(d) Cyanobacteria
1.5 μm
(e) Pruple sulfur
bacteria
Figure 10.2

5. Heterotrophs Obtain their organic material from other organisms
Are the consumers of the biosphere

6. Chloroplasts: The Sites of Photosynthesis in Plants
The leaves of plants
Are the major sites of photosynthesis
Vein
Leaf cross section
Figure 10.3
Mesophyll
CO2 O2
Stomata

7. Chloroplasts Are the organelles in which photosynthesis occurs
Contain thylakoids and grana
Chloroplast
Mesophyll
5 µm
Outer
membrane
Intermembrane
space
Inner
Thylakoid
Granum
Stroma
1 µm

8. Tracking Atoms Through Photosynthesis: Scientific Inquiry
Photosynthesis is summarized as

9. The Two Stages of Photosynthesis: A Preview
Photosynthesis consists of two processes
The light reactions (light-dependent)
-Needs Light!
The Calvin cycle (light-independent)
-Does NOT need light!

10. Light-Dependent Reaction
The light reactions
Occur in the grana
Split water, release oxygen, produce ATP

11. The Calvin Cycle (Light-Independent Reaction)
Occurs in the stroma
Forms sugar from carbon dioxide, using ATP for energy
The Calvin Cycle (Light-Independent Reaction)

12. Overview of Photosynthesis
CO2
Light
LIGHT REACTIONS
CALVIN
CYCLE
Chloroplast
[CH2O]
(sugar)
NADPH
NADP +
ADP
+ P O2
Figure 10.5
ATP

13. 3 Factors that Affect Photosynthesis
Carbon Dioxide (CO2)
Without CO2, the plant would not have one of the raw materials needed in the photosynthesis equation
CO2 is used in the first step of the Calvin Cycle
Temperature
The temperature must be in the appropriate range for the plant in order for photosynthesis to properly occur

14. 3 Factors that Affect Photosynthesis
Intensity of Light
If the intensity of light is lower, the available energy for photosynthesis is lower.
If light is not available at all, the light-dependent reactions cannot occur (nor can they provide the materials used in the light-independent reactions)

15. Exit Slip
What are the reactants for photosynthesis and the products?