1. Photosynthesis Where does all that glucose come from? Chapter 3

2. How does it do that?

3.  Photosynthesis uses radiant energy from the sun to fix carbon dioxide into carbohydrates  The captured radiant energy is stored within the bonds of the carbohydrate as chemical energy What is it? CO 2 radiant energy Photosynthesis glucose

4.  Photosynthesis is used by many autotrophs to make their own food  egs. vascular plants, algae, cyanobacteria

5. That’s a lot of photosynthesis

6. http://www.smhi.se/weather/baws_ext/info/2004/Baltic_algae_2004_en.htm

7. Overall (Net) Equation O2O2 glucose CO 2 H2OH2O H+H+ H+H+ Energy CO 2 + H 2 O + energy  glucose + O 2 Photosynthesis

8. glucose + O 2  CO 2 + H 2 O + energy Overall (Net) Equation CO 2 H2OH2O H+H+ H+H+ Energy O2O2 glucose Cellular RespirationPhotosynthesis Photosynthesis and Cellular Respiration appear to be reverse processes, but they use very different mechanisms

9. Similarities  Both cellular respiration and Photosynthesis are similar in that both use: 1.electron transport chains 2.dissolved enzymes 3.membrane-enclosed space for chemiosmosis

10. Plant Tissues  Plants are made of various types of tissues  egs. Stem, leaves, roots, reproductive organs  The main site of photosynthesis is the leaves, although chloroplasts are found in all green plant parts

11. Leaves vascular bundle palisade mesophyll spongy mesophyll epidermis cuticle stomate EpidermisMesophyllVascular Bundles

12. Leaves  Leaves have 3 main types of tissues: 1.Epidermis  Usually one cell thick and secrets a waxy cuticle to prevent water loss  Pores called stomata found in lower epidermis epidermis vascular bundle palisade mesophyll cuticle spongy mesophyll stomate

13. Leaves 2.Mesophyll  Most photosynthesis occurs here  Two layers of parenchyma cells Palisade layer ◦Cell arrangement maximizes exposure to light Spongy layer ◦Loose arrangement of cells leaving air spaces for gas exchange epidermis vascular bundle palisade mesophyll cuticle spongy mesophyll stomate

14. Leaves 3.Vascular Bundles  Transport system of the plants  Contains xylem (water transport) and phloem (sugar transport) epidermis vascular bundle palisade mesophyll cuticle spongy mesophyll stomate

15. Opening/Closing Stomata  The guard cells (stomata) can be opened and closed to regulate gas exchange and minimize water loss in leaves Chloroplast Pore Guard Cells OPENCLOSED

16. Opening Stomata  To open the stomata:  Potassium ions (K + ) are actively pumped into the guard cells (uses ATP)  This causes the GCs to become hypertonic to their surroundings  Water is drawn into the GCs, increasing turgor pressure OPEN ATP K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ H2OH2O H+H+ H+H+ H2OH2O H+H+ H+H+ Cell is now hypertonic to surroundings

17. Closing Stomata  To close the stomata:  K + pumps deactivated allowing ions to diffuse out  Water drawn back out of the GC with the K + ions  Decrease in turgor pressure makes GCs go limp (flacid) ATP K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ OPEN

18. Closing Stomata  To close the stomata:  K + pumps deactivated allowing ions to diffuse out  Water drawn back out of the GC with the K + ions  Decrease in turgor pressure makes GCs go limp (flacid) K+K+ K+K+ K+K+ K+K+ K+K+ K+K+ OPEN H2OH2O H+H+ H+H+ H2OH2O H+H+ H+H+ Cell is now hypotonic to surroundings

19. Closing Stomata  To close the stomata:  K + pumps deactivated allowing ions to diffuse out  Water drawn back out of the GC with the K + ions  Decrease in turgor pressure makes GCs go limp (flacid) OPEN H2OH2O H+H+ H+H+ H2OH2O H+H+ H+H+ CLOSED