1. © 2013 Pearson Education, Inc. Lectures by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fifth Edition, and Campbell Essential Biology with Physiology, Fourth Edition – Eric J. Simon, Jean L. Dickey, and Jane B. Reece Chapter 7 Photosynthesis: Using Light to Make Food

2. Figure 7.0

3. THE BASICS OF PHOTOSYNTHESIS – Photosynthesis is used by plants, algae (protists), and some bacteria, transforms light energy into chemical energy, and uses carbon dioxide and water as starting materials. © 2013 Pearson Education, Inc.

4. – The chemical energy produced via photosynthesis is stored in the bonds of sugar molecules. – Organisms that use photosynthesis are photosynthetic autotrophs and the producers for most ecosystems. THE BASICS OF PHOTOSYNTHESIS © 2013 Pearson Education, Inc.

5. Figure 7.1 Plants (mostly on land) Photosynthetic Protists (aquatic) PHOTOSYNTHETIC AUTOTROPHS Photosynthetic Bacteria (aquatic) Micrograph of cyanobacteria Kelp, a large, multicellular alga Forest plants LM

6. Chloroplasts: Sites of Photosynthesis – Chloroplasts are the site of photosynthesis and found mostly in the interior cells of leaves. – Inside chloroplasts are interconnected, membranous sacs called thylakoids, which are suspended in a thick fluid called stroma. – Thylakoids are concentrated in stacks called grana. © 2013 Pearson Education, Inc.

7. – The green color of chloroplasts is from chlorophyll, a light-absorbing pigment that plays a central role in converting solar energy to chemical energy. – Stomata are tiny pores in leaves where carbon dioxide enters and oxygen exits. Chloroplasts: Sites of Photosynthesis © 2013 Pearson Education, Inc.

8. Figure 7.2-3 Interior cell LM Stroma Granum Thylakoid space Chloroplast Inner and outer membranes Colorized TEM Leaf cross section Stomata Vein CO 2 O2O2 Photosynthetic cells

9. The Simplified Equation for Photosynthesis – In the overall equation for photosynthesis, notice that the reactants of photosynthesis are the waste products of cellular respiration. © 2013 Pearson Education, Inc.

10. Figure 7-UN01 Carbon dioxide 6 O 2 6 CO 2 6 H 2 O C 6 H 12 O 6 Water Glucose Photo- synthesis Oxygen gas Light energy

11. – In photosynthesis, sunlight provides the energy, electrons are boosted “uphill” and added to carbon dioxide, and sugar is produced. The Simplified Equation for Photosynthesis © 2013 Pearson Education, Inc.

12. – During photosynthesis, water is split into hydrogen and oxygen. – Hydrogen is transferred along with electrons and added to carbon dioxide to produce sugar. – Oxygen escapes through stomata into the atmosphere. The Simplified Equation for Photosynthesis © 2013 Pearson Education, Inc.

13. A Photosynthesis Road Map – Photosynthesis occurs in two multistep stages: 1.the light reactions convert solar energy to chemical energy and 2.the Calvin cycle uses the products of the light reactions to make sugar from carbon dioxide. © 2013 Pearson Education, Inc.

14. Figure 7.3-1 Light H2OH2O O2O2 Chloroplast Light reactions NADPH ATP ––

15. Figure 7.3-2 Calvin cycle CO 2 NADP + ADP P Sugar Light H2OH2O O2O2 Chloroplast Light reactions NADPH ATP  ––

16. The Nature of Sunlight – Sunlight is a type of energy called radiation, or electromagnetic energy. – The distance between the crests of two adjacent waves is called a wavelength. – The full range of radiation is called the electromagnetic spectrum. © 2013 Pearson Education, Inc.

17. Figure 7.4 Visible light Wavelength (nm) Radio waves 400 500 600 750 700 Wavelength  580 nm Micro- waves Gamma rays Infrared UV X-rays 10 –5 nm 1 nm 1 m1 m Increasing wavelength 380 10 –3 nm10 3 nm 10 6 nm 10 3 m

18. Figure 7.5 Light Chloroplast Absorbed light Transmitted light (detected by your eye) Reflected light

19. Chloroplast Pigments – Chloroplasts contain several pigments: 1.Chlorophyll a – absorbs mainly blue-violet and red light and – participates directly in the light reactions. 2.Chlorophyll b – absorbs mainly blue and orange light and – participates indirectly in the light reactions. © 2013 Pearson Education, Inc.

20. – Carotenoids absorb mainly blue-green light, participate indirectly in the light reactions, and absorb and dissipate excessive light energy that might damage chlorophyll. – The spectacular colors of fall foliage are due partly to the yellow-orange light reflected from carotenoids. Chloroplast Pigments © 2013 Pearson Education, Inc.

21. Figure 7.7

22. Figure 7-UN04 Carbon dioxide 6 O 2 6 CO 2 6 H 2 O C 6 H 12 O 6 WaterGlucose Photosynthesis Oxygen gas Light energy

23. Figure 7-UN05 Light H2OH2O O2O2 Chloroplast Light reactions NADPH ATP Calvin cycle CO 2 NADP  ADP P Sugar Stack of thylakoids Stroma – – Sugar used for cellular respiration cellulose starch other organic compounds