2. Introduction to Photosynthesis

3. Objectives Discuss energy flow through living systems
Identify the parts of a leaf
Outline the process of photosynthesis

4. Overview
Plants convert the energy of sunlight into the energy of chemical bonds of carbohydrates

5. Importance of Photosynthesis
Provides energy for plants
Provides energy for animals that eat plants
Provides energy for animals that eat animals that ate plants
Provides energy for organisms that break down all of the above
Provides the energy for most ecosystems on earth

6. But that’s not all.. Gives us food
Provides wood, paper, other wood based products
Provides cotton, hemp, other fibers
Is the original source of energy in coal and oil
Plants are pretty

7. Photosynthesis consumes Carbon Dioxide
But wait, there’s more..
Photosynthesis consumes Carbon Dioxide
And Produces Oxygen

8. History Jan Van Helmont
Found the mass of a pot of soil and a seedling. Watered the seedling for five years. Found the mass again
Concluded that the increase in mass came from water

9. History Joseph Priestly
Found that a candle goes out when placed in a jar. However, the candle keeps burning if a sprig of mint is also placed in the jar.
Concluded that plants produce [Oxygen]

10. History Jan Ingenhousz
Showed that Priestley’s experiment only works in the light.
Concludes that light is necessary for plants to produce oxygen

11. History
Magic School Bus class

12. Chemical basis of photosynthesis
CO2+H C(H2O)+O2
Light

13. Balanced Equation
Light
6CO2+6H C6H12O6+6O2

14. CO2+H20 C(H2O)+ O2 Sun Entropy Photosynthesis Respiration
The BIG Picture

15. Leaf Structure – p.655

16. Leaf structure

17. Requirements for Photosynthesis
                        

18. Light
Mostly violet, blue and red wavelengths from the visible spectrum

19. Chlorophyll (a and b) – green
Pigments
Substances that absorb certain wavelengths of light and reflect other wavelengths
Thus they are colored
Examples:
Chlorophyll (a and b) – green
Carotene – red/orange
Xanthophylls - yellow

20. Energy Storing Compounds
Energy trapped by molecules can be used to lift electrons to a higher energy level.
From that higher energy level the electrons can fall down to their original energy level and do work along the way.
Example – a solar cell that powers a calculator

21. Or… The high-energy electrons can be bound to an electron carrier.
Nicotinamide Adenine Dinucleotide Phosphate
NADP+ accepts a pair of high energy electrons and a Hydrogen ion to become NADPH

22. Energetics ATP – Adenosine Triphosphate
Energy storing compound used by every living cell
Energy harvested via the light reaction is stored in ATP and used to convert CO2 into sugar by using the H obtained from splitting water.

23. Function of ATP ATP If the cell need energy it breaks ATP into ADP+P
If the cell has energy to store it makes ATP

24. Overview of Photosynthesis
Light reactions
Dark reactions – Calvin Cycle

25. Light Reactions Energy from sunlight is trapped,
water molecules are split,
NADPH and ATP are formed,
O2 is given off as a waste gas

26. Calvin Cycle
Products from the light reactions and CO2 from the atmosphere are used to produce carbohydrates

27. Objectives Discuss energy flow through living systems
Identify the parts of a leaf
Outline the process of photosynthesis

28. Homework
See planner.

29. Have a nice day