Warm – Up 4/2  Under what conditions would a plant close the guard cells on its leaves?  Analyze why this is an important ability for plants.  (Hint: Think reactants and products for photosynthesis)

PHOTOSYNTHESIS

8.1Photosynthesis uses light energy to make food Site of photosynthesis in plants / contain CHLOROPHYLL, which absorbs light energy

Parts of a Leaf

8.1Chloroplasts A.Site of photosynthesis in plants B.Contain CHLOROPHYLL C.Absorbs light energy 2. THYLAKOIDS Saclike photosynthetic membranes (photosystems found inside) Light-collecting units of chloroplast (contain pigments and proteins) PHOTOSYSTEMS 3. STROMA Region outside thylakoid membranes (Calvin cycle occurs here) 6. GRANUM Stack of thylakoids 5. INNER MEMBRANE 4. OUTER MEMBRANE

8.1Photosynthesis Definition: Process of turning light energy from the sun into chemical energy 6CO 2 + 6H the sun’s energy  C 6 H 12 O 6 + 6O 2 Carbon Dioxide Water Glucose Oxygen ENERGY STORED

8.1Photosynthesis: Overview LIGHT REACTION Requires Light Occurs in Thylakoids CALVIN CYCLE Links carbon atoms to make glucose Occurs in Stroma

8.1Photosynthesis: Overview LIGHT-DEPENDENT REACTIONS 1.Requires light 1.Uses energy from light to produce oxygen gas and energy carriers: ATP and NADPH by splitting water CALVIN CYCLE (Light Independent) 1.Does NOT require light 1.Uses ATP and NADPH from light-dependent reactions to produce high- energy glucose from CO 2. Glucose can be stored for a long time.

Light Dependent Reactions  Light excites electrons, which then travel down the ETC producing energy (NADPH and ATP)  Reactants – Water  Products – O 2 and Energy (ATP and NADPH)

Calvin Cycle (Light Independent Reactions  CO 2 enters the Calvin Cycle and is added to a carbon chain with energy.  Additional Energy is used to modify the carbon chain and create carbohydrates (sugars)  Reactants – ATP, NADPH, and CO 2  Products – Glucose, ADP, and NADP +  Location – Stroma

Calvin Cycle (Light Independent Reaction) Calvin Cycle (Light Independent Reaction) 12 NADPH ADP 12 NADP + 5-Carbon Molecules Regenerated 6 6 ADP

8.3Photosynthesis Summary Chloroplast Light H2OH2O O2O2 CO 2 Sugars NADP + ADP + P Calvin Cycle Light- dependent reactions Calvin cycle

Factors Affecting Photosynthesis Amount of H 2 O Temperature Intensity of Light