Warm – Up  Stomata-small openings in leaves that allow gases and water to diffuse into and out of the leaf  Guard cells – special cells that surround the stomata. Control the opening and closing of stomata

Warm-up  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

Parts of a Leaf Most photosynthesis occurs in the palisade/palisade mesophyll layer

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

Requirements of Photosynthesis A. Carbon dioxide B. Water C. Sunlight

Requirements of photosynthesis D. Pigments 1. Pigments – colored substances that absorb or reflect light 2. The process of photosynthesis begins with plant pigments absorbing light energy 3. The main pigment in green plants is chlorophyll. Chlorophyll absorbs mostly red and blue light and reflects most green and yellow light.

Requirement of photosynthesis E. Energy storing compounds 1. Include ATP and NADPH 2. ATP and NADPH are produced during the light reactions 3. ATP and NADPH are used to drive the dark/ light independent reactions/Calvin Cycle F. Photosynthesis also requires enzymes

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: 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.

The light-dependent reactions  KEY CONCEPT-The light reactions convert the energy from the sun into energy in ATP and NADPH (energy storing compounds).  The light reactions require light.  Light energy splits water (this is why these reactions are sometime called photolysis) When water is split oxygen, hydrogen ions, and electrons are released.

The light-dependent reactions  The electrons travel across an electron transport chain.  Electron transport chain – series of electron carrier proteins that shuttle high- energy electrons.  These electrons are eventually used to make NADPH.

The light-dependent reactions  The hydrogen ions travel across the thylakoid membrane and are eventually used to produce ATP.  The energy storing compounds (ATP and NADPH) that are produced during the light reactions drive the light-independent reactions.

Light-independent reactions/Calvin Cycle  Key concept-the light-independent reactions convert the ATP and NADPH into the high energy sugars (including glucose)  The light-independent reactions do not require light (hence the name)

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

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