Photosynthesis
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Photosynthesis is the process by which plants and other organisms use sunlight, water and carbon dioxide to produce oxygen and energy in the form of glucose. Chlorophyll, located in chloroplasts, absorbs sunlight and uses the energy to convert carbon dioxide and water into oxygen and glucose through a two-step process - the light reactions and Calvin cycle. Plants appear green because chlorophyll, the main photosynthetic pigment, absorbs most wavelengths of visible light except green, which it reflects, giving leaves their green color.
Photosynthesis
- 2. THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH
- 3. Almost all plants are photosynthetic autotrophs, as are some bacteria and protists Autotrophs generate their own organic matter through photosynthesis Sunlight energy is transformed to energy stored in the form of chemical bonds (a) Mosses, ferns, and flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria THE BASICS OF PHOTOSYNTHESIS
- 4. Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO 2 + 6 H 2 O + light energy -> C 6 H 12 O 6 + 6 O 2
- 5. Food Chain
- 6. THE FOOD WEB
- 7. WH Y AR E P LAN TS G RE EN?
- 8. Electromagnetic Spectrum and Visible Light Gamma rays X-rays UV Infrared & Microwaves Radio waves Visible light Wavelength (nm)
- 9. Different wavelengths of visible light are seen by the human eye as different colors. WHY ARE PLA NTS GRE EN? Gamma rays X-rays UV Infrared Micro- waves Radio waves Visible light Wavelength (nm)
- 10. Sunlight minus absorbed wavelengths or colors equals the apparent color of an object. The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Reflected light
- 11. WHY ARE PLA NTS GRE EN? Plant Cells have Green Chloroplasts The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids).
- 12. Chloroplasts absorb light energy and convert it to chemical energy Light Reflected light Absorbed light Transmitted light Chloroplast THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED
- 13. What colors are being absorbed and what colors are being reflected?
- 14. Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water AN OVERVIEW OF PHOTOSYNTHESIS Carbon dioxide Water Glucose Oxygen gas PHOTOSYNTHESIS
- 15. Chloroplasts: Sites of Photosynthesis Photosynthesis Occurs in chloroplasts, organelles in certain plants All green plant parts have chloroplasts and carry out photosynthesis The leaves have the most chloroplasts The green color comes from chlorophyll in the chloroplasts The pigments absorb light energy
- 16. In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts A chloroplast contains: stroma, a fluid grana, stacks of thylakoids The thylakoids contain chlorophyll Chlorophyll is the green pigment that captures light for photosynthesis Photosynthesis occurs in chloroplasts
- 17. The location and structure of chloroplasts LEAF CROSS SECTION MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane space Outer membrane Inner membrane Thylakoid compartment Thylakoid Stroma Granum Stroma Grana
- 18. Chloroplasts contain several pigments Chloroplast Pigments Chlorophyll a Chlorophyll b Carotenoids Figure 7.7
- 19. Different pigments absorb light differently
- 20. A Photosynthesis Road Map Chloroplast Light Stack of thylakoids ADP + P NADP Stroma Light reactions Calvin cycle Sugar used for Cellular respiration Cellulose Starch Other organic compounds
- 21. The O 2 liberated by photosynthesis is made from the oxygen in water (H + and e - ) Plants produce O 2 gas by splitting H 2 O
- 22. Review: Photosynthesis uses light energy to make food molecules Light Chloroplast Photosystem II Electron transport chains Photosystem I CALVIN CYCLE Stroma Electrons LIGHT REACTIONS CALVIN CYCLE Cellular respiration Cellulose Starch Other organic compounds
- 23. Review What is the ultimate source of all energy? In what form does light energy come to the earth? What compounds absorbs wavelengths? How do we see colors?
- 24. Review Which compound reflects the green wavelengths thereby making plants green? Where would we find this compound? Where in a leaf do we find pigments? What are the small openings in leaves for gas exchange called?
Editor's Notes
- #14: The green plant reflects the color green and absorbs all other wavelengths. The purple flower reflects the color purple and absorbs all other wavelengths. The white flower reflects all colors and absorbs no wavelengths. The orange flower reflects the color orange and absorbs all other wavelengths. The red rose reflects the color red and absorbs all other wavelengths. Photos courtesy of flowerpictures.net and picturesof.net
- #24: Ask these questions one at a time as review. Click to get to the next question 1. The sun Wavelengths Pigments The wavelengths not absorbed by pigments are reflected as color In the chloroplast
- #25: Pigments Chlorophyll Chloroplast