Chapter 8: Photosynthesis

1. Chapter 8: Photosynthesis Energy and Life

2. Rainy Day • Suppose you earned extra money from a part-time job. You might be tempted to spend all the money, but instead, you decide to open a savings account. • 1. What are the benefits to having a bank account? • 2. What might you need to do if you need some of this money? • 3. What might your body do if it has more energy than it needs to carry out its activities? • 4. What would your body do if it needed more energy?

3. Energy and Life A. Autotrophs and heterotrophs • Autotrophs can make own food directly with aid of the sunlight. a. plants • Heterotrophs cannot make own food directly. Depends on others such as plants for food. • Humans • Mushrooms-need to decompose other organisms

4. Chemical NRG and ATP • Energy=in the form of light, heat, electricity • ATP (Adenosine Tri Phosphate) • Most important energy storing compound

5. ATP and ADP • ATP (Adenosine Tri Phosphate) • Fully charged energy • Uses enzymes to break down to make energy • Energy is released when ATP breaks down to ADP and a phosphate group • ADP (Adenosine Di Phosphate) • Not fully charged energy • Needs enzymes to help add one more Phosphate to make ATP

6. ATP and cells • Cells use ATP when they move and during active transport • Most cells have a little amount of ATP, enough to last for seconds. • ATP is not good at storing over a long period of time but it is VERY efficient when used.

7. Glucose • A monosaccharide sugar, C6H12O6, occurring widely in most plant and animal tissue. It is the principal circulating sugar in the blood and the major energy source of the body. • Stores more than 90 times more chemical energy than ATP • Cells can get ATP and ADP from carbs.

8. Photosynthesis • Photosynthesis-plants use energy of the sun to make food such as, glucose.

9. Scientists • van Helmont • How does a seed grow into a tree? • Weighed a pot of soil and seed = 5 kg • Watered for 5 years • Seed gained about 75 kg • The soil was unchanged throughout • He concluded that water made the seed grow into a tree. Is that all that is needed to make plants grow?

10. NO!!! Plants need: REACTANTSPRODUCTS

11. Scientists continued… • Priestly • Joseph Priestly (1733 – 1804)    Priestly was a Unitarian minister and chemist.  He did the following experiments: • Summary: • burning candle + bell jar →  candle goes out + add a mint plant  →  candle can be relit • mouse + bell jar →  dead mouse + add a mint plant →  mouse lives

12. For the visual learner

13. Questions • Why did the candle burn out when placed under bell jar? • Why could the candle be relit after allowing it growth with a mint plant? • Why does a mouse die when it is placed under a bell jar? • Why was the mouse able to survive when placed in the jar with a mint plant? • Assuming a supply of water was available to both mint plant and mouse; could the mouse and plant survive indefinitely under the jar?  Explain.

14. And yet…one more scientist • Ingenhousz • Finds that aquatic plants produce oxygen bubbles in the light but not in the dark. • Concludes that plants need SUNLIGHT to produce OXYGEN

15. Light and Pigment • Pigment is light absorbing material • Chlorophyll • 2 types of chlorophyll • Chlorophyll a • Chlorophyll b • Chlorophyll absorbs light in the red and blue regions • WHY are plants green? • Other plants contain different pigments to absorb other parts of the spectrum…ex. carotene

16. 8.3 Rxns of Photosynthesis • Photosynthesis takes place in the chloroplast.

17. Thylakoid • Contains photosynthetic membranes • Photosystems 1 and 2

18. Grana • Stack of Thylakoids

19. 2 Stages of Photosynthesis • 1.Light Dependent Reaction • Energy is captured to make storing compounds. • Occurs inside the photosynthetic membrane • Thylakoid membrane • 2.Light Independent Reaction • Does not require light directly • Can occur in the light • Uses stored energy from Light Rxn to make glucose in the absence of light. • Occurs outside the photosynthetic membrane • Stroma

20. Light Dependent Rxn • 4 processes • 1. Light Absorption- photosystems capture light in membrane • 2. Electron Transport- NADP+ (enzyme carrier that makes NADPH) NADPH helps build molecules in the cell. • 3. O2 Production- takes electrons from H2O forms O2 gas (released into the air) • 4. ATP Formation- H2O splits, inside the + charges collide with the – charges outside. Produces energy to attach P+ADP=ATP.

21. Light Independent Rxn(Calvin Cycle or Dark Rxn) • Calvin Cycle uses 6 molecules of CO2 to make a single 6-carbon sugar • Plants use the sugar to make more complex carbs like starches and cellulose. • Uses ATP and NADPH from Light Rxn to carry on Dark Rxn.

22. Factors affecting Photosynthesis • Shortage of water • Temperature • Intensity or amount of light

23. Plants • Multicellular eukaryotes • Carry out photosynthesis using green pigments…chlorophyll a & b What is the advantage of two different chlorophylls?

24. What do plants need to survive? • Water, carbon dioxide, sunlight

25. How plants get nutrients • Xylem- vascular tissue that carries water UP from the roots to every part of the plant. (xy-hi) • Phloem- vascular tissue responsible for transport of nutrients and the carbs produced by photosynthesis. (ploe-low)

26. Classification • Gymnosperms-cone bearing • Most common are: spruce, pine, firs, cedars, evergreens.

27. Female-actual cone Male-pollen cones Reproduction of Gymnosperms

28. Classification • Angiosperm- flowering plants (flowers or fruit bearing)

29. Reproduction of Angiosperms

30. Important Terms • Annuals- plant yearly • Biennials- 2 years • Perennials- through the years