Photosynthesis

(Life from )Light

A little backgroundOrganisms

autotrophs heterotrophs

Make own food Obtain food from others

The fuel of living things

Adenosine triphosphate

Energy needs of Life

• All life needs a constant input of energy– Heterotrophs (animals, fungi, most bacteria)

• get their energy from “eating others”• consumers of other organisms• consume organic molecules

– Autotrophs (plants, some bacteria)• get their energy from “self”• use sunlight energy to synthesize

organic molecules - PHOTOSYNTHESIS

PHOTOSYNTHESIS

• The process by which light energy is converted into chemical energy [ATP] and stored in organic compounds (sugar).

CO2

Where does photosynthesis occur? In the chloroplasts!

absorbsunlight & CO2

makeenergy & sugar

Light: absorption spectrum– Different types of chlorophyll can absorb different

wavelengths of light

Chloroplasts

• Green because absorb light wavelengths in red & blue and reflect green back out

THAT IS WHY PLANTS LOOK GREEN TO US! WE SEE WHAT IS RELFECTED.

In a Chemical Equation….

• REACTANTS are what is put in• PRODUCTS are what you get out

• REACTANTS PRODUCTS

6CO2 6H2O C6H12O6 6O2light

energy+ ++

Photosynthesis: Overall Equation

+ water + energy glucose + oxygencarbondioxide

6CO2 6H2O C6H12O6 6O2light

energy+ ++

So what does a plant need?

• Takes in– CO2– H2O– light

• Releases– O2

• Produced and moved around– sugars

roots

shoot

leaves

How can a leaf do this? Let’s briefly examine the leaf structure

H2O CO2

CO2

O2 H2O

Stoma (pore/hole)

O2

Stomata • Function of stomata

– CO2 in

– O2 out

– H2O out

guard cell

Stomata (pore or hole)

Putting it all together • Making a living…

– sunlight• leaves = solar collectors• photosynthesis

– gases: CO2 in & O2 out • stomata = gases in & out

– H2O• roots take in water from soil• pulled up by leaf evaporation

– nutrients• roots take in from soil

Resources

• www.bio.kimunity.com• Miller, Ken and Joe Levine. Prentice hall

Biology. Pearson Education Inc. New Jersey, 2005.