1. Photosynthesis: Using Light to make Food
Bio Honors
Ch. 7

2. Plants are AUTOTROPHS = create their own food to use for energy.
PHOTOSYNTHESIS Plants convert the energy of sunlight into energy stored in chemical bonds of carbohydrates:
Simple sugars- in the form of glucose
Larger polysaccharides - starch or cellulose

3. REQUIREMENTS FOR PHOTOSYNTHESIS
Reactants Products 6 CO2 + 6 H2O C6H12O6 + 6 O2
Light

4. REQUIREMENTS FOR PHOTOSYNTHESIS
Light
Pigments – colored substances that
absorb or reflect light
Chlorophyll -main pigment used in photosynthesis.
REFLECTS GREEN LIGHT! (absorbs red/blue-violet)
Photons of light hits the chlorophyll and excites the electrons in chlorophyll.

5. Electromagnetic Spectrum

6. REQUIREMENTS FOR PHOTOSYNTHESIS continued…
3) Energy storing compounds
ATP
E- carrier – NADPH
4) Water –absorbed through the ROOTS; transported to the cells with XYLEM
5) Carbon dioxide (CO2) – gas from the surrounding environment are brought into the plant cells through STOMATA, small pores in the leaves.

7. Leaf Stomata

8. Structure of the Chloroplast (site of photosynthesis)
NOT THE SAME!

9. 2 Stages of Photosynthesis: THE LIGHT & DARK REACTIONS

10. Stage 1: Light Reactions
Takes place in the thylakoid membranes, inside the chloroplasts.
Involves an electron transport chain, moving particles across protein channels in the membrane.
Zoom in!

11. Stage 1: LIGHT REACTIONS
1) Light absorption-
clusters of pigment molecules (chlorophyll) absorb photons of light; excites e- in the chemical structure of the chlorophyll molecules with energy.
Electrons move from Photosystem II to Photosystem I.
Electron transport – high energy electrons transported along electron carriers, and then to NADP+ to form NADPH.

12. Stage 1: Light Reactions continued…
3) oxygen production – splitting 2 water molecules, leaving 4 H+ and O2 .
* REMEMBER: PLANTS PRODUCE THE OXYGEN THAT WE BREATHE!
ATP formation-
Move H+ ions through ATP synthase (same as seen in cellular respiration!)
Movement of H+ through the ATP synthase moves energy used to bond a P to ADP, forming ATP

13. Light reactions: Quick Animation)
2) Detailed Animation of Light reactions

14. STAGE 2: Calvin Cycle (Dark Reactions)
Called “dark” because sunlight does not play a role!
Takes place in the STROMA, area around the thylakoids in the chloroplast.
Basic Steps:
CO2 absorb from atmosphere; enter ATP/NADPH produced in the light reactions.
CO2 enters and attaches to RuBP with the help of rubisco (enzyme)
Moves around the cycle, ATP and NADPH become ADP and NADP+ and a G3P (half glucose) is released
* 2 turns of cycle = 1 glucose
Animation of Calvin Cycle (Dark Reactions)

16. Photosynthesis and Global Warming

17. How does photosynthesis help regulate global temperatures?

18. So how could we help reduce
ANSWER:
Photosynthesis absorbs CO2 from the atmosphere.
DECREASES the amount of CO2 in the atmosphere, which can trap radiation and increase temperatures.
So how could we help reduce
global warming???

19. PLANT MORE TREES AND OTHER PLANTS!!!

20. Plant Structures
Chapters 31 and 32 notes

21. Objs Plant Tissues

22. Root cap - Meristematic tissue

23. Meristem= MITOSIS HOTSPOT! (cell growth/reproduction center)
Meristematic tissue

24. Viewing Leaf Stomata