1. End Show Slide 1 of 28 Copyright Pearson Prentice Hall Biology

2. End Show Slide 2 of 28 Copyright Pearson Prentice Hall 8-2 Photosynthesis: An Overview

3. End Show Slide 3 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall 8-2 Photosynthesis: An Overview The key cellular process identified with energy production is photosynthesis. Photosynthesis is the process in which green plants use the energy of sunlight to convert water and carbon dioxide into high-energy carbohydrates and oxygen.

4. End Show Slide 4 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall The Photosynthesis Equation What is the overall equation for photosynthesis?

5. End Show Slide 5 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall The Photosynthesis Equation The equation for photosynthesis is: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 carbon dioxide + water sugars + oxygen Light

6. End Show Slide 6 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall The Photosynthesis Equation Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen.

7. End Show Slide 7 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall The Photosynthesis Equation O2O2 CO 2 + H 2 0 Sugar ADP NADP + Light-Dependent Reactions (thylakoids) H2OH2O ATP NADPH Calvin Cycle (stroma) Light energy

8. End Show Slide 8 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall Light and Pigments What is the role of light and chlorophyll in photosynthesis?

9. End Show Slide 9 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall Light and Pigments How do plants capture the energy of sunlight? In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll.

10. End Show Slide 10 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall Light and Pigments Plants gather the sun's energy with light-absorbing molecules called pigments. The main pigment in plants is chlorophyll. There are two main types of chlorophyll: chlorophyll a chlorophyll b

11. End Show Slide 11 of 28 8-2 Photosynthesis: An Overview Chlorophyll absorbs light well in the blue-violet and red regions of the visible spectrum. Copyright Pearson Prentice Hall Light and Pigments Wavelength (nm) Estimated Absorption (%) 100 80 60 40 20 0 400 450 500 550 600 650 700 750 Chlorophyll b Chlorophyll a Wavelength (nm)

12. End Show Slide 12 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall Light and Pigments Chlorophyll does not absorb light will in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green. Estimated Absorption (%) 100 80 60 40 20 0 400 450 500 550 600 650 700 750 Chlorophyll b Chlorophyll a Wavelength (nm)

13. End Show Slide 13 of 28 8-2 Photosynthesis: An Overview Copyright Pearson Prentice Hall Light and Pigments Light is a form of energy, so any compound that absorbs light also absorbs energy from that light. When chlorophyll absorbs light, much of the energy is transferred directly to electrons in the chlorophyll molecule, raising the energy levels of these electrons. These high-energy electrons are what make photosynthesis work.

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