Balancing Equations??? Not Again…..Writing Prompt ~ 03.11.2009

• Look carefully at this equation. What does this equation relate to? Explain how you came up with your answer…

CO2 + H2O + light Glucose + O2

Reactants Products

Balance the equation…..

• ____CO2 + ____H2O + Light 1C6H12O6 + ___O2

Where does this reaction occur?

Photosynthesis

• It is the conversion of solar energy to chemical energy in a form that can be utilized by living organisms.

• 2 steps– Light reaction - Light Dependent reaction– Calvin cycle - Light Independent reaction

• occurs in the light as well as the dark

What’s the Ultimate energy source?• The sun is ultimate energy

source for virtually ALL life on earth.

• Plants and Cyanobacteria generate their own food by converting SOLAR energy to the stored energy of glucose (food & building materials).

• Plants and animals must then convert that food to an energy form useable at the cellular level.

Equation for Photosynthesis

CO2 + H2O + light -----> Glucose + O2

Reactants Products

Where does this reaction occur?

Where do these inputs come from?

• Energy (light) comes from the sun (or some other artificial light source.

• Water comes from the soil into the plant roots & through the plant to the leaves.

• Carbon Dioxide comes from the air and enters the leaves through stomata.

Light Dependent Reaction

• Light strikes chloroplasts of a leaf cell

• Energy from light energizes chlorophyll

• Energized chlorophyll splits a water molecule, giving off the oxygen as a gas (waste) and capturing the hydrogen atoms to use later.

• This is the place where you’ve learned that plants give off oxygen!!

Calvin Cycle(Light Independent Reaction)

• The fixation of carbon dioxide from atmosphere to make sugar (storing carbon to use for building / growing)

• Light is NOT necessary for this reaction- it takes place both during the day and at night

• Combines CO2 with other carbon containing compounds form to sugar - Glucose (6 carbons)

• When you learned that plants take in CO2

(carbon dioxide) this is where its used.

What kinds of light are involved?

Check it out…..