Chapter 6

1. Chapter 6 Photosynthesis

2. “Let it Burn!” The forest fire surged ahead as foresters, a professor, and some state officials hold a hurried conference. The officer in charge trots over to the firefighters. “Get your crews out of here!” he orders. “We are going to let it burn!”

4. Only recently, letting a fire burn would have been unthinkable! Conservationists now recognize that fires are a natural part of the environment, and they are not always bad.

5. Experts may decide to let fire recycle forest. Calcium, phosphates, nitrogen, trace elements, and other natural materials left after a forest fire nourish new growth. A LOT of animals may die but a few may prosper from the new plant growth that springs from the ashes. Sometimes the best thing to do with a forest fire is to let it burn.

7. Do you agree with the “let it burn” philosophy?

8. The very air we breath… • You have learned in science class that plants take in CO2 and give off O2, and animals take in O2 and give off CO2. Did you know that the plants that give you the most oxygen are not the familiar farms, fields or forests.

9. By far, most of the oxygen we breath comes from photosynthesis. This process is the way plants, including tiny marine algae, make their own food. Do you know that these microscopic marine algae produce most of the oxygen we breathe? • If you ever wondered how important algae is, consider how important breathing is!

11. What would happen if no more sunlight?

12. What would happen if there were no more green plants on Earth?

13. What happens when plants shut down in the winter  how do we still survive?

14. Photosynthesis • Photosynthesis – A series of chemical reactions where light energy is converted into chemical energy (glucose ~ C6H12O6) for plants to use. • Glucose is the basic fuel or energy source for all cells.

15. Two Problems • Plants receive sunlight faster than they can convert it to glucose. • Energy is released from glucose faster than a plant can use it.

16. What do plant cells do with all the excess energy? • They store it! • Energy is stored in ATP (Adenosine Triphosphate) • Made in the mitochondria. • Its chemical structure can be quickly changed to store & release energy. • Removing a phosphate releases energy. • ATP  A – P – P • Adding a phosphate stores energy. • A – P – P  ATP

17. Equation for Photosynthesis 6CO2 + 6H2O + light energy  C6H12O6 + 6O2 Carbon dioxide + water + sunlight  glucose + oxygen Photosynthesis occurs in 2 stages…

18. Chlorophyll • acts as an NRG trap. • Captures light NRG and makes it available for producing food. • Photosynthesis can only occur in the presence of chlorophyll (chloroplasts)

19. 1st Stage: Light Reactions • Plants receive light energy from the sun. • Chlorophyll becomes energized & traps light energy. • That energy is used to split H2O molecules. • Oxygen from H2O is released into the air. • Excess energy is stored in ATP • 2 Hydrogen molecules (from H2O) & ATP are used later in the 2nd stage.

20. 2nd Stage: Dark Reactions • Plants receive Carbon Dioxide CO2 from the air. • Carbon & Hydrogen molecules combine using the energy from ATP to form Glucose. • Glucose provides the plant with ENERGY!

21. Light Reactions & Dark Reactions

23. http://photoscience.la.asu.edu/photosyn/education/colorchange.htmlhttp://photoscience.la.asu.edu/photosyn/education/colorchange.html