1. How autotrophs (plants) manufacture their own food
Photosynthesis
How autotrophs (plants) manufacture their own food

2. What is photosynthesis?
Photosynthesis is the process by which autotrophs manufacture their own food (glucose) using sunlight, carbon dioxide and water.

3. Energy Conversion
During the process of photosynthesis, light energy from the sun is converted into chemical energy that can be stored and transported in plants.

4. Requirements for Photosynthesis
Chlorophyll or other pigment (found in autotrophs)
Carbon dioxide (CO2) from the atmosphere
Water (H2O) from the soil or atmosphere
Light, usually as solar energy from the sun
CO2
Photosynthesis

5. Products of Photosynthesis
Glucose (C6H12O6) - sugar
Oxygen gas (O2)

6. Chemical Equation 6CO2 + 6H2O C6H12O6 + 6O2 light dioxide
carbon water glucose oxygen
dioxide
In the presence of light energy, six molecules of carbon dioxide combine with six molecules of water to produce one molecule of glucose and six molecules of oxygen.

7. Factors Affecting the Rate of Photosynthesis
1. Light intensity (very high intensity can damage the chlorophyll)
2. Availability of raw materials (CO2, H2O)
3. Temperature (optimum is ºC)

8. Site of Photosynthesis: The Chloroplast
Photosynthesis takes place in the chloroplasts of plant cells.
It primarily occurs in the leaves.

9. Structure of a Chloroplast
Thylakoids are the saclike membranes that contain chlorophyll.
A granum is a stack of thylakoids
The stroma is the liquid-filled space inside the chloroplast.
granum
stroma
thylakoids

10. Two phases of Photosynthesis
Light-dependent phase
Light-independent Phase (Calvin Cycle)

11. 1. Light-Dependent Phase (take place in thylakoids)
a. Light energy is absorbed by chlorophyll and changes into ATP.
b. Some ATP is used to split the water molecule (H2O) into hydrogen & oxygen.
c. Oxygen (O2) is released into the atmosphere.

12. Light-Independent Phase (Calvin Cycle) – takes place in stroma
May happen in the light or in the dark
a. ATP (from previous phase) and hydrogen (from the water molecule that was split) combine with CO2 (from the atmosphere).
b. The end result is glucose: C6H12O6

14. Remember, if you like to eat and breathe…thank a plant!