1. Photosynthesis

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

3. How do plants make energy & food?
Plants use the energy from the sun
to make ATP energy
to make sugars
glucose, sucrose, cellulose, starch, & more
sun
ATP
sugars

4. What do plants need to grow?
The “factory” for making energy & sugars
chloroplast
Fuels
sunlight
carbon dioxide
water
The Helpers
enzymes
Make ATP! Make sugar! I can do it all… And no one even notices!
sun
CO2
ATP
enzymes
sugars
H2O

5. Energy and Life
Plants and some other types of organism are able to use light energy from the sun to produce organic compounds (glucose).
Autotrophs – organisms that are able to synthesize their own food.
Heterotrophs – obtain energy by consuming other organisms.

6. Photosynthesis
Plants use the energy of sunlight to convert water and carbon dioxide into oxygen and high energy carbohydrates.

7. 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

8. Structure of a Leaf Xylem – carries water from the roots to leaves.
Phloem – carries food (glucose) from leaves to the roots.
Stomata – tiny holes in bottom of the leaf that function in gas exchange.
Guard cells – control the opening and closing of guard cells.

9. Trapping Energy from Sunlight
Photosynthesis happens in two phases.
The light-dependent reactions convert light energy into chemical energy. (ATP)
2. The molecules of ATP produced in the light-dependent reactions are then used to fuel the Calvin Cycle or light-independent reactions that produce simple sugars.
The general equation for photosynthesis is written as CO2 + 6H2O→C6H12O6 + 6O2

10. 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)

11. Light and Pigments
In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll, a molecule found in chloroplasts.
Plants gather the suns energy with light absorbing molecules called pigments (chlorophyll).

12. Why are leafs green?
There are two types of chlorophyll, chlorophyll a and chlorophyll b. These pigments absorb red and blue light, and reflect green.

13. Other Pigments
Carotenoids, which produce yellow, orange, and brown colors in such things as corn, carrots, and daffodils.
Anthocyanins, which give color to such familiar things as cranberries, red apples, concord grapes, blueberries, cherries, strawberries, and plums.
Why do leaves change colors in the autumn?
During the growing season, chlorophyll is continually being produced and broken down and leaves appear green. As night length increases in the autumn, chlorophyll production slows down and then stops and eventually all the chlorophyll is destroyed. The carotenoids and anthocyanins that are present in the leaf are then unmasked and show their colors.

14. Paper Chromotography
Paper chromatography is a technique for separating and identifying mixtures that are or can be colored, especially pigments found in plants.

15. Rate of Photosynthesis
Amount of Water available
Temperature
Light Intensity

16. Comparing photosynthesis and Cellular Respiration