Photosynthesis. Plants = Producers All energy on earth comes from the sun. Solar energy is converted...
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Transcript of Photosynthesis. Plants = Producers All energy on earth comes from the sun. Solar energy is converted...
Photosynthesis
Plants = Producers• All energy on earth comes from the sun.
• Solar energy is converted by:– Plants
– Algae (underwater plants)
– Cyanobacteria (photosynthetic bacteria – sometimes called blue-green algae)
Overview – draw this diagram
Overview – write this in your notes
1. Carbon dioxide and water are taken in by plants
2. Plants absorb light energy and convert it to cellular energy called “ATP”
3. Energy is used to change carbon dioxide and water into sugar molecules called glucose.
4. Sugar is converted to starch and stored for use by the plant, and by animals when they eat plants.
Chloroplasts• Chloroplasts in plant
cells are where photosynthesis takes place.
• Chloroplasts look green because they contain the pigment CHLOROPHYLL.
• Chlorophyll reflects green light and absorbs the other colors of visible light.
Photosynthesis is a Chemical Change
• It changes carbon dioxide and water into two new substances – oxygen and sugar.
Photosynthesis is a Chemical Change
Chemical Changes can be written using words in a CHEMICAL EQUATION
• carbon + water makes oxygen + glucose dioxide
Photosynthesis is a Chemical Change
Chemical changes can also be written with symbols instead of words
• carbon + water makes oxygen + glucose dioxide
• CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
When we use numbers and symbols to represent a chemical change, this is
called a CHEMICAL EQUATION
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
On the left side of an equation are the REACTANTS, or the ingredients needed
for the chemical reaction to happen.
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
On the right side of an equation are the PRODUCTS, or the substances that are
produced as a result of the reaction.
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
The ARROW always goes left – to – right and shows how the reaction happens.
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
In any chemical reaction, the atoms in the ingredients have to be the same as the atoms in the products, just re-arranged.
What 3 kinds of atoms are involved in photosynthesis?
Photosynthesis is a Chemical Change
There are only carbon, hydrogen, and oxygen atoms in the reactants and in the
products.
Reactants Products
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
But count the NUMBERS of each atom. Are they the same on both sides of the
equation?
Reactants Products
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
2 Carbon 6
3 Hydrogen 12
3 Oxygen 8
Reactants Products
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change1 Carbon 6
2 Hydrogen 12
3 Oxygen 8
THIS CAN’T BE – ATOMS CAN’T BE CREATED!
Reactants Products
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change2 Carbon 6
3 Hydrogen 12
3 Oxygen 8
THERE MUST BE MORE THAN ONE MOLECULE OF SOME OF THESEReactants Products
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
We need to “balance” the chemical equation to make the same numbers and kinds of
atoms on each side.
Reactants Products
CO2 + H2O O2 + C6H12O6
Photosynthesis is a Chemical Change
We need to “balance” the chemical equation to make the same numbers and kinds of
atoms on each side.(Adding a number in front of the molecule is like multiplying every
atom by that number)
Reactants Products
6CO2 + 6H2O 6O2 + C6H12O6
Photosynthesis is a Chemical Change
___ Carbon ___
___ Hydrogen ___
___ Oxygen ___
Now count the atoms on each side…
Reactants Products
6CO2 + 6H2O 6O2 + C6H12O6
Even though we can explain it, photosynthesis is still
miraculous!
