1. Energy Comes From Food All living things need energy to function This energy comes from food The ultimate source of energy for al life on earth is the sun Some organisms make their own food by converting energy from the sun into chemical energy in the form of organic molecules such as glucose. This process is photosynthesis  Photo - Light  Synthesis- To make

2. Obtaining Food Autotrophs Produce their Own Food Autotrophs Produce their Own Food Heterotrophs Must Consume Food Heterotrophs Must Consume Food Also called producersAlso called consumers 2

3. Photosynthetic Organisms (a) Mosses, ferns, and flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria (c) Euglena

4. Photosynthesis Photosynthesis is the overall process by which sunlight (solar energy) chemically converts water and carbon dioxide into chemical energy stored in simple sugars (glucose). Anabolic Reaction (small molecules combined)  What molecules are combined  CO 2 +H 2 O Endergonic (uses energy)

5. Where does photosynthesis occur? produce their own food (glucose) Autotrophs: produce their own food (glucose) EX. Plants, some bacteria and protists Location in plants: - Mesophyll cells in leaves contain a high concentration of chloroplasts Stoma Mesophyll Cell Chloroplast

6. How does a plant obtain the needed materials? Vascular Bundle (Vein) Contains the Xylem and Phloem Xylem carries water to the plant Phloem carries food (glucose) to various parts of the plant

7. Stomata (stoma) Pores in a plant’s cuticle through which water and gases are exchanged between the plant and the atmosphere. Guard cells surround the stomata to help reduce the loss of water through transpiration Guard Cell Carbon Dioxide (CO 2 ) Oxygen (O 2 )

8. Photosynthesis Occurs in the Chloroplast Surrounded by a double membrane Contain thylakoids, membranes that are arranged as flattened sacs Connected stacks of thylakoids are called grana (granum, singular) Thylakoids contain chlorophyll A solution called stroma surrounds grana

9. Thylakoid Thylakoid Membrane Thylakoid Space Granum

10. Chloroplast Pigments In addition to water, carbon dioxide, and light energy, photosynthesis requires pigments  Pigments compounds that absorb light Chlorophyll is the primary light-absorbing pigment in autotrophs Absorb violet and blue Reflect green

11. Fall Colors In addition to the chlorophyll pigments, there are other pigments present. During the fall, the green chlorophyll pigments are greatly reduced revealing the other pigments. Carotenoids are pigments that are either red or yellow.

12. Photosynthesis Occurs in Two Stages Light Dependent Reaction  1 st step of photo synthesis that needs light Light Independent Reaction(Calvin Cycle)  2 nd step of photosynthesis does not need light

13. Light Dependent Reaction Sugars are not made Solar energy is absorbed by chloroplasts Water molecules are split to create oxygen, which is release as a waste product. The splitting of water molecules allows for the temporary transfer of the solar energy to electrons released by the broken bonds. This energy is used to make ATP and NADPH.

14. Light Reactions- Specific Steps  Step one: pigments absorb light energy  Step two: pigment electrons gain the energy and jump an energy level (described as “excited electrons”). Electron symbol = e -

15. Light Reactions- Specific Steps  Step three: Excited electrons enter an electron transport chain (a series of proteins).  As the electrons are passed from protein to protein, chemical energy is generated and stored in ATP and NADPH (energy storage molecules or energy “carriers”).

16. Light Reactions- Photolysis Aside from the chain of reactions that occur when pigments absorb light energy, there is another occurrence going on “behind the scenes” during the light reactions. This occurrence is known as photolysis. Photo=lightLysis= to split  During photolysis, water molecules are split apart into hydrogen ions, electrons, and oxygen.  Oxygen gas is released as waste into the atmosphere.

17. The Calvin Cycle or Light-Independent Reactions Does not require solar energy CO 2 from the atmosphere and energy carried by ATP and NADH are used to make glucose Sugars are used to store chemical energy for later Glucose can be used as an energy source through cellular respiration or it can be converted to organic molecules  Proteins, carbohydrates, fats/lipids, DNA/RNA

18. Steps of the Calvin Cycle 1. Carbon fixation: One carbon atom from CO2 is added to a 5-carbon sugar called ribulose biphosphate (RuBP). 2. PGA Formation: The unstable six-carbon sugar formed in step 1 is then split into 2 molecules of phosphoglyceric acid (PGA). 3. Use of ATP and NADPH: A series of reactions involving ATP and NADPH from the light reactions converts a molecule of PGA into PGAL (phosphoglycer-aldehyde), another 3-carbon compound.

19. 4. Glucose production: After several rounds of the Calvin cycle, two molecules of PGAL leave the cycle to form glucose.

20. Photosynthesis Chemical Equation Even though photosynthesis is represented by this equation it does not show all steps that occur in the process 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 6 CO 2 molecules and 6 H 2 O molecules are needed to make one glucose and six O 2 molecules

21. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 In this formula: Each reactant (CO 2 and H 2 O) are broken down at different stages of photosynthesis  CO 2  Calvin Cycle  H 2 O  Light Dependent Each of the products (O 2 and C 6 H 12 O 6 ) are formed in different stages of the process  O 2  Light Dependent  C 6 H 12 O 6  Calvin Cycle Solar Energy is needed to break down the water molecules

22. The Water Loss Dilemma The number one problem that land plants face is dehydration. Plants must open their stomata to let the carbon dioxide that is required for photosynthesis. But anytime the stomata are open, there will be water loss. On a hot, dry day, most plants close their stomata to conserve water. This means that the rate of photosynthesis will drastically slow down since no CO 2 can enter the leaf.

23. `Factors Affecting the Rate of Photosynthesis Water- A shortage of water in the ground can slow or stop photosynthesis Temperature- The process of photosynthesis depends upon the action on enzymes  At very low or very high temperatures, photosynthesis may stop entirely Light Intensity – Increasing the light intensity increases the rate of photosynthesis.