1. Photosynthesis

2. THE BIG PICTURE Scientists discovered that in the presence of light, plants transform CO 2 and water into carbohydrates and release oxygen. _____________ + ____________ _______________ + ____________ Carbon dioxide WATERSugars Oxygen 6 CO 2 _____________ + ____________ _______________ + ____________ 6 H 2 OC 6 H 12 O 6 6 O 2 →

3. PHOTOSYNTHESIS: Reactants & Products LIGHT ENERGY 6CO 2 + 6H 2 O SUGAR + 6O 2

4. In addition to water and carbon dioxide, __________________ and __________________ are needed for photosynthesis to happen. chlorophyll light energy

5. Because light is a form of ___________, any molecule that absorbs light also ___________the energy from the light. ENERGY ABSORBS

6. Pigments Chlorophyll A is the most important photosynthetic pigment. The pigments are embedded in the membranes of the chloroplast in groups called photosystems.

7. Chlorophyll a Chlorophyll b Absorption of Light by Chlorophyll a and Chlorophyll b SO WHAT WAVELENGTHS ARE BEST FOR PHOTOSYNTHESIS? THE ONES CHLOROPHYLL ABSORBS THE BEST ________ and _______________ red Blue-violet

8. Chlorophyll a Chlorophyll b Absorption of Light by Chlorophyll a and Chlorophyll b NEITHER KIND OF CHLOROPHYL L IS VERY GOOD AT ABSORBING _________ LIGHT! GREEN

9. That’s why leaves LOOK GREEN….. Chlorophyll doesn’t absorb…. it ___________ GREEN light! REFLECTS

10. PHOTOSYNTHESIS OVERVIEW

11. Photosynthesis: The Chemical Process Occurs in two main phases. –Light reactions –Dark reactions (aka – the Calvin Cycle) Light reactions are the “photo” part of photosynthesis. Light is absorbed by pigments. Dark reactions are the “synthesis” part of photosynthesis. Trapped energy from the sun is converted to the chemical energy of sugars.

12. PHOTOSYNTHESIS Light-Dependent Reaction Light-Independent Reactions CALVIN CYCLE Light & Water Oxygen ATP NADPH Carbon Dioxide (CH 2 O) n

13. Factors that Affect Photosynthesis ____________________ Water is one of the raw materials needed, so A shortage of water can ________________ photosynthesis AMOUNT OF WATER Desert plants and conifers that live in dry conditions have a waxy coating on their leaves to prevent water loss. slow or stop

14. Factors that Affect Photosynthesis Photosynthesis enzymes function best between 0° C - 35° C At temperatures above or below this range, photosynthesis will slow or stop Conifers in winter may carry out photosynthesis only occasionally TEMPERATURE http://www.sustland.umn.edu/maint/images/evergreen10.jpg

15. Factors that Affect Photosynthesis ____________________ More light increases rate of photosynthesis up to a certain level until plant reaches its maximum rate of photosynthesis LIGHT INTENSITY

16. THE BIG PICTURE These experiments led to work by later scientists who finally discovered that in the presence of light, plants transform CO 2 and water into carbohydrates and release oxygen. _____________ + ____________ _______________ + ____________ Carbon dioxide WATERSugars Oxygen 6 CO 2 _____________ + ____________ _______________ + ____________ 6 H 2 OC 6 H 12 O 6 6 O 2 →

17. Photosynthesis is the process by which plants and few other organisms use to transform light energy into chemical energy. Plants use chlorophyll to collect the energy from the sun rays to create the food they need, the food we eat, the oxygen we, all living creatures need to breath, and fossil fuels, like coal, oil and gas that the industrialized world needs. Without this process, life on earth would end, and the only organisms left would be the chemosynthesis bacteria. Photosynthesis is basic in the maintenance of life on earth. THE BIG PICTURE Why Should You Care?