 WHY do leaves change color in the fall?  Form a hypothesis about why you think leaves change colors.

ANSWER: The same reason bananas ripen. Explanation Explanation 2

Autotroph vs. Heterotroph  Autotroph  able to make their own food  EX: plants use sun energy  Producers  Photoautotrph – use energy of light to make organic molecules from inorganic  Heterotroph  Obtain energy from food consumed  EX: Humans, leopards, mushrooms  Consumers

Photosynthesis  Definition: Process used to convert light into sugar from carbon dioxide and water  Energy in the form of Carbohydrates  Produce oxygen as by-product Reactants Products Animation – Active Art

Requirements 1.Sunlight 2.Pigments (chlorophyll) 3.ATP 4.NADPH 5.Water 6.Carbon Dioxide

1. Sunlight

SUNLIGHT (continued)  Perceived as “white light”  Electromagnetic energy – radiation that travels in rhythmic waves  Wavelength – distance between crests of 2 adjacent waves  Visible spectrum – radiation your eye sees as color  ROYGBIV  Absorbed (not seen) or reflected (seen)  Photons = particles that carry light; fixed quantity

Why are plants usually green?

2. ATP  Adenosine Triphosphate  Definition: Provides cellular energy  Made of:  Adenine  Ribose  3 phosphate groups

ATP continued  ADP – Adenosine Diphosphate  2 phosphates instead of 3 Break ATP– release energy from bond ADP + P – energy needed to make ATP

Conversion of ADP to ATP Fully charged “battery” ATP ADP Animation 2

3. Pigments  Definition: Light absorbing molecules that gather the sun’s energy  EX: Types of Pigment  Chlorophyll a  Chlorophyll b  Found in chloroplasts  Reflect green light  Absorb blue/violet and red  Carotenoid (yellow-orange)  Carrots  Why are Flamingos pink? Link Link

Structure of Chloroplasts  Trap light (chlorophyll) and transfer energy to excite electrons  Electrons drive photosynthesis to work Light Energy CO 2 + H 2 OSugars + O 2 Stroma (area between disks) Grana (stack of thylakoids) Thylakoid (disklike)

Important parts of Plant  Mesophyll – green tissue on interior of leaf where chloroplasts are found  Stomata – tiny pores where carbon dioxide enters and oxygen exits  Chloroplast  Stroma – fluid filled space where dark reaction occurs  Thylakoid – interconnected membranous sac where light reaction occurs  Grana – stack of thylakoids

4. NADPH  Accepts electrons  “Truck” that carries electrons (e-)  High energy electrons (analogy – hot coals)  NADP+ (Low energy)  NADPH (High energy)  One way to trap sunlight  Helps build glucose later NADP + e- (hydrogen ion)  NADPH

NADPH Analogy Hot CoalsNeed pan to Carry Hot Coals: Electrons As Pan: ……?

5. Water  Sunlight energy splits into:  2 Hydrogen ions (H+)  Helps make ATP and NADPH  1 oxygen  Used in release of oxygen gas (O 2 )

6. Carbon Dioxide  Comes from environment  Burning of fossil fuels  Animals/humans release  Used to make glucose

ADP and ATP review Matching Game

Requirements of Photosynthesis Seek & Sort Provides H+ ions Animals releaseAbsorbs light UV Rays WavelengthsSplits water Chlorophyll a & b Receives H+ ions Photons Provides energyROYGBIV Cellular energy ChloroplastProduces O 2

Photosystem II Hydrogen Ion Movement ATP synthase ATP FormationPhotosystem I Electron Transport Chain Stroma Thylakoid Membrane Inner Thylakoid Space

Light Reactions  “Light dependent reactions”  Purpose: change light energy into chemical energy of ATP and NADPH  ATP and NADPH to be used in Calvin Cycle  Requires light  Occurs in thylakoid membrane  Produces:  Oxygen (released into air)  ATP  NADPH

Review of Light reaction Review animation

 STEPS of Light Reaction 1.Light absorbed  Pigments/Photosystems (photosystem II occurs 1 st )  Electrons stimulated 2.Water is split  O 2 released as by-product  H+ ions produced 3.ATP and NADPH formed  Produced by electrons in thylakoid Electron transport chain (ETC)Electron transport chain (ETC)  Move into dark reactions SUMMARY Light + water  NADPH, ATP, O 2 Text book videoReview Animation

Chemiosmosis  Drives ATP synthesis using the potential energy of a concentration gradient of hydrogen ions across a membrane  Photophosphorylation – using light to do

Light reaction

Dark Reactions  Other names: Light independent or Calvin Cycle  Purpose: Change CO 2 into sugar by using ATP & NADPH  ATP & NADPH from light reaction  Does not need light  Takes place in stroma  6 cycles = 1 glucose  Sugar used for growth or food storage

Overview of Photosynthesis

Light- Dependent Reactions Calvin Cycle ATP NADPH NADP + ADP + P Sugars CO 2 CHLOROPLAST Light H2OH2O O2O2 Matching summary game

Impacts on Photosynthesis LLLLight CCCCarbon Dioxide TTTTemperature WWWWater

Why is deforestation so bad?  Explanation Explanation  Deforestation pictures Deforestation pictures Deforestation pictures

Green house effect

Photosynthesis and the Environment  Greenhouse effect – warming of the atmosphere as a result of CO2, CH4, and other gases that absorb infrared radiation and slow its escape into the atmosphere  Global warming – slow but steady rise in earth’s surface temperature