Name:___________________________________________________
Photosynthesis- A Chemical Reaction in the Chloroplast
READ, UNDERLINE, HIGHLIGHT, CIRCLE:
One of the main ideas about photosynthesis is that
plants use light energy from the sun to turn
inorganic reactants into organic products.
Remember that photosynthesis is a chemical
reaction.
Chemical reactions use energy to turn reactants
into totally different products. Let’s review what a
chemical reaction looks like again.
Water (H2O)
Carbon Dioxide
(CO2)
Glucose (C6H12O6)
Oxygen (O2)
Light energy
(from the sun)
The reactants are the molecules that go into a
chemical reaction. The products are what the
reactants change into.
In the photosynthesis chemical reaction, a plant
starts with carbon dioxide (CO2) and water
(H2O). The plants get carbon dioxide from the air.
Animals, like humans, breathe in oxygen and breath
out carbon dioxide. Plants get water from the
ground through their roots. Carbon dioxide and
water are reactants that are turned into glucose
(C6H12O6) and oxygen (O2), the products of
photosynthesis. The energy needed to turn these
reactants into products comes from the sun.
Class Period:_____________
TAKE NOTES, ASK QUESTIONS:
By definition, an organic substance is something
that contains BOTH Carbon (C) and Hydrogen
(H). Looking at the chemical formulas of the
reactants and products in photosynthesis, we can
see that glucose is the only molecule that contains
both Carbon (C) and Hydrogen (H). Therefore,
glucose is an organic molecule.
Water
Carbon Dioxide
H2O + CO2
REACTANTS
Light Energy
Glucose
Oxygen
C6H12O6 + O2
PRODUCTS
Organic molecules store energy in the bonds
between their atoms. Remember how different
atoms and elements can form bonds with one
another? Well, these bonds can also be broken
apart. When the bonds in organic molecules are
broken apart, energy is released.
Plants break down glucose to release energy.
Since glucose is an organic molecule, it has energy
stored in the bonds. Remember that glucose is plant
food made by photosynthesis in the chloroplast, but
the mitochondria is the organelle that breaks
down food, like glucose, to release energy for the cell.
QUESTIONS:
1. What are the reactants of photosynthesis?
2. What are the products?
3. Where does the energy come from to drive the photosynthesis reaction?
4. What is an organic molecule?
5. Which product of photosynthesis is organic?
6. What is the chemical formula for glucose?