1. Photosynthesis: Life from Light and Air

2. Trapping Energy from Sunlight
The process that uses the sun’s energy to make simple sugars is called photosynthesis.

3. AN OVERVIEW OF PHOTOSYNTHESIS
Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water
PHOTOSYNTHESIS

4. Plants are energy producers
Like animals, plants need energy to live
unlike animals, plants don’t need to eat food to make that energy
Plants make both FOOD & ENERGY
animals are heterotrophs(consumers)
plants are autotrophs (producers)

5. What do plants need to grow?
The “factory” for trapping energy & making sugars
chloroplast
Fuels
sunlight
carbon dioxide
water
The Products
- Oxygen & Glucose
The Helpers
Enzymes
sun
CO2 O2
enzymes
sugars
H2O

6. Bring In Let Out Move Around leaves shoot roots  light CO2 H2O O2
sugars
leaves
shoot
roots
6CO2
6H2O
C6H12O6
6O2
light
energy  +

7. Chloroplasts absorb sunlight & CO2 Leaf Leaves CO2
Chloroplasts in cell
Chloroplast
Chloroplast
Chloroplasts
contain
Chlorophyll
make ENERGY & SUGAR

8. Stomates & Guard Cells in the leaf
Function of stomates
CO2 in
O2 out
H2O out
gets to leaves for photosynthesis
Function of guard cells
open & close stomates
guard cell
stomate

9. THE LIGHT REACTIONS: CONVERTING SOLAR ENERGY TO CHEMICAL ENERGY Visible radiation drives the light reactions
Certain wavelengths of visible light drive the light reactions of photosynthesis
X-rays
Micro- waves
Radio
waves
Gamma rays UV
Infrared
Visible light
Wavelength (nm)

10. pigments in the chloroplast
To trap the energy in the sun’s light, the thylakoid membranes contain pigments, molecules that absorb specific wavelengths of sunlight.
Wavelengths that are NOT absorbed are reflected (bounce off) or transmitted (pass through)
So the material in which the pigment is found appears to be the color of the wavelengths that are NOT absorbed
Photosynthetic pigments: can absorb light energy & make it available for conversion to chemical energy .
Light
Reflected light
Chloroplast
Absorbed light

11. pigments in the chloroplast
Chlorophyll a: most common pigment in chloroplast (absorbs blue &red light and reflects green light thus giving the chloroplast a green color)(chloro = green phylla + leaf)
Accessory pigments: additional pigments that absorb different wavelengths (carotene, chlorophyll b, & xanthophyll)

13. Factors Affecting Rate of Photosynthesis
Temperature: increases rate up to a certain point
Light Intensity: increases rate up to a certain point
CO2 level: Increases rate up to a certain point
Water: decrease water, decrease photosynthesis
Minerals; Ex. Magnesium, Nitrogen