Photosynthesis is the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to produce glucose and oxygen. It occurs in the chloroplasts of photosynthetic organisms, where chlorophyll absorbs sunlight and thylakoids split water to produce oxygen, while the stroma converts carbon dioxide into sugar. Photosynthesis converts sunlight into chemical energy stored in glucose and transforms carbon dioxide and water into oxygen and energy-storing sugars that all organisms can use.

1. BIOLOGY
Unit 3 Notes:
Photosynthesis

2. (1) What is Photosynthesis?
The reacting of sunlight,
carbon dioxide gas, and
water in order to produce
glucose (sugar) and
oxygen gas.

4. (2) The Chemical Equation
REACTANTS
PRODUCTS
Sunlight + CO2 + H2O 
Carbon
Dioxide
Water
C6H12O6 + O2
Glucose
(Sugar)
Oxygen

5. (3) Where does it happen?
• Photosynthetic organisms only.
• Inside the organelle called the CHLOROPLAST.
– Light is absorbed by the chloroplast’s Thylakoids.
– Water is broken apart in the thylakoids, forming oxygen
gas.
– Carbon dioxide is converted to sugar in the stroma.
• Chlorophyll (a green pigment) in chloroplasts
absorb the light energy.

6. (Let’s Draw a Picture of the
Chloroplast & Its Parts )

9. (4) How Does It Cycle Matter + Energy?
• ENERGY:
– Converts electromagnetic energy (from the sun) into
chemical potential energy (stored in the sugar).
– Makes un-useable energy, useable for all nonphotosynthetic life forms.
• MATTER:
– Takes CO2 and H2O… breaks the bonds, rearranges the
atoms, and forms new compounds.
– Makes un-useable gas compounds, into energy storing
sugars for all living things.

10. (5) Connecting Photosynthesis
& Respiration
• The glucose and oxygen produced in
photosynthesis is necessary to begin
cellular respiration.
• The carbon dioxide and water needed to
begin photosynthesis, is made during
cellular respiration.