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CHAPTER 8 Photosynthesis Sheldon: Revised 2011. PLANTS USE SUNLIGHT ENERGY TO MAKE THEIR OWN FOOD You Tube Plants and Sunlight.

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Presentation on theme: "CHAPTER 8 Photosynthesis Sheldon: Revised 2011. PLANTS USE SUNLIGHT ENERGY TO MAKE THEIR OWN FOOD You Tube Plants and Sunlight."— Presentation transcript:

1 CHAPTER 8 Photosynthesis Sheldon: Revised 2011


3 Where does your energy come from? Autotrophs Plants use sunlight to make their own food Heterotrophs Obtain energy from foods they consume (plants and animals)

4 Energy in Chemical Bonds EXOTHERMIC: When a bond is broken, energy is released. ENDOTHERMIC: It takes energy in to hold bonds together.

5 Endothermic or Exothermic? Endothermic Video (digital Thermometer)Endothermic Video Barium Hydroxide Octahydrate with Ammonium Thiocyanate (teacher)Barium Hydroxide Octahydrate with Ammonium Thiocyanate Exothermic Video (Fe2O3 + sugar)Exothermic Video Sodium and Water in Trash Can Exothermic Thermite Myth Busters Thermite Exothermic Make an Instant Cold Pack from Sodium Acetate (Nurd Rage) Supernova Make Glow Sticks - The ScienceSupernova Make Glow Sticks - The Science

6 Cell’s Batteries ATP Adenosine Tri Phosphate VIDEO: howstuffworks (ATP)howstuffworks (ATP)






12 Where might ATP be used? Used directly for: –Muscle movement –Synthesis of protein –Firefly flash –Sperm swimming –White blood cells moving YouTube MacrophageouTube Macrophage

13 Photosynthesis is the most important chemical process on earth because: It provides food for virtually all organisms

14 Overall Equation for Photosynthesis




18 We see reflected wavelengths We don’t see absorbed wavelengths

19 Chlorophyll The green pigment (light-absorbing molecules) in plants in their chloroplasts

20 Light Spectrum From Sun

21 Chlorophyll a and b Chlorophyll a Absorbs 430 + 662 nm Absorbs Blue- violet and red Chlorophyll b Absorbs 460 + 642 nm Absorbs Blue and orange-red

22 Chlorophyll absorbs light well in these colors.

23 Plants Reflect Green

24 Also plants have other pigments: Carotenoids (orange) Phycoerythrin (red) Flavins (orange-yellow) Anthocyanin – blue-purple


26 The Beginning of Photosynthesis Experiments What do you see? Photosynthesis History Video

27 Photosynthesis History Van Helmont Plants gain most of their mass from H 2 O 1580-1644

28 Priestley’s Experiment: Plants release O 2 sprig of mint Collected oxygen 1733- 1804

29 Jan Ingenhousz 1730-1799 physician Light is necessary for plants to produce O 2 NO LIGHT-no oxygen



32 Cross Section of Leaf 5 2 9 3 8 1 7 4 6 10


34 4. Mesophyll = middle leaf Made of: 6. Palisade Layer (vertical, tightly packed) + 7. Spongy Layer (has air spaces) Is where photosynthesis takes place

35 6. Palisade Layer Tightly packed columns of plant cells

36 Palisade Layer has lots of chloroplasts

37 10. Air Space: Houses Gases in 7. Spongy Layer

38 5. Cuticle Waxy covering of epidermis (reduces water loss)


40 1. Stomata (pl.) (sing.= stoma) Opening to let gases and water vapor in and out Controlled by guard cells In lower epidermis

41 8. Guard Cells Control the opening of the stoma Stoma LabBench

42 LE 36-14 20 µm Which stoma is open and which is closed? You Tube Guard Cells

43 LE 36-15a Cells turgid/Stoma open Changes in guard cell shape and stomatal opening and closing (surface view) Radially oriented cellulose microfibrils Vacuole Cell wall Guard cell Cells flaccid/Stoma closed

44 LE 36-15b Cells turgid/Stoma open Role of potassium in stomatal opening and closing Cells flaccid/Stoma closed H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O K+K+


46 9. Vein Xylem - tubes carrying water Phloem - tubes carrying food Leaf Cross Section Review

47 Photosynthesis Intro VIDEO howstuffworks photosynthesis

48 CHLOROPLASTS The photosynthesizing organelle

49 Thylakoids Disks containing chlorophyll

50 Grana (pl.) Granum (sing.) Stacks of thylakoid disks

51 Stroma Cytoplasm of the chloroplast Where LIR (light independent reaction) occurs

52 Light Dependent Reaction Occurs: thylakoid membrane Produce ATP and NADPH

53 Vocabulary ATP production is called “photophosphorylation” (uses light) (adds P to ADP)

54 Get Colored Pencils LDR and ILR Diagrams

55 First LEO goes GER LEO = loss of electrons is oxidation GER = gain of electrons is reduction

56 Redox Reactions

57 oxidized reduced Gain H Lose H

58 LDR Light Dependent Reaction

59 Vocabulary PHOTOSYSTEM (or Reaction Center) uses light to energize molecules (electrons) PSI P700 PSII P680 (Absorb sunlight)

60 1. Photon of light hits chlorophyll Excites an electron e- jumps around pigments until it hits chlorophyll a (reaction center) Demo with ping-pong balls!

61 To ETC

62 ETC (Electron Transport Chain) Accepts high energy electrons and moves them to low energy electrons The energy lost is given to an electron carrier ( NADP+) Virtual Cell: PhotosynthesisVirtual Cell: Photosynthesis

63 e- flow to NADP+ to form NADPH NADPH is an electron carrier Nicotinamide Adenine Dinucleotide Phosphate.

64 2. Water is Split Oxygen is released H+ ions build up in thylakoid interior Light reactions (click on the four steps)Light reactions PS II Kid Like Animation PSI

65 3. H+ ions pumped through the thylakoid membrane H+ ions in chemiosmosis

66 4. Chemiosmosis Build-up of H+ ions pumped through the ATP synthase to make ATP (P joins ADP)


68 Summary of Energy transformation in the light reactions Light energy starts the process Flow of Electrons –Splitting of water molecules provides electrons –Release of oxygen molecules from water –Accumulation of H+ in thylakoid spaces –LDR VideoLDR Video

69 Reduction of NADP to NADPH by adding electrons and H+ Production of ATP using the H+ in thylakoid spaces –ATP synthase enzyme –Powered by flow of H+ from the thylakoid spaces –ADP + Phosphate (Pi) ---> ATP –McGraw-Hill ETC and ATP SynthesisMcGraw-Hill ETC and ATP Synthesis

70 PSI and PSII Animation You Tube PS II Photosynthesis AnimationVCAC: CellularYou Tube PS IIPhotosynthesis AnimationVCAC: Cellular

71 LIR (Light Independent Reaction) aka Calvin Cycle Calvin Cycle

72 LIR (Light Independent Reaction) aka Calvin Cycle Found: in the stroma of the chloroplast Does not need sunlight but is run by ATP and NADPH made in the LDR Here is where the carbohydrates are actually assembled McGraw-Hill Calvin Cycle

73 Summary of the Calvin Cycle Addition (fixing) of gaseous CO 2 to RUBP, a 5 carbon compound in the stroma of chloroplasts. Energy input from ATP (ATP from the light reactions ---> ADP + Phosphate back to the light reactions) Addition of H+ and energy from NADPH

74 Summary (cont.) (NADPH from the light reactions ---> NADP+ back to the light reactions Production of carbohydrates for storage, transport, and biosynthesis Recycling of 5 carbon compound (RUBP) to fix more CO 2

75 Rubisco Most abundant protein in the world! Recyclable! Used in the first step of fixing (making useable) atmospheric CO 2 Attqaches 5-c sugar to CO 2 Ribulose-1,5-bisphosphate carboxylase oxygenase,


77 Light Independent Reaction YouTube - The Calvin Cycle or (animated and narrated)YouTube - The Calvin Cycle or YouTube - Calvin Cycle Video (simple overview-animated diagram)YouTube - Calvin Cycle Video YouTube - Photosynthesis-Calvin Cycle and Cyclic Electron Flow (your fav science singer)YouTube - Photosynthesis-Calvin Cycle and Cyclic Electron Flow

78 Now Sing Along YouTube - Photosynthesis - The Light Reactions YouTube - MY FAVE SONG: THE PHOTOSYNTHESIS SONGYouTube - MY FAVE SONG: THE PHOTOSYNTHESIS SONG YouTube - Photosynthesis Song (with subtitles) EXTRA CREDIT- 5 points You write the lyrics to a common song about photosynthesis. Must have at least 5 stanzas.

79 OR Make a model of either the LDR or LIR or chloroplast Each must include at least 5 labeled items

80 Label the thylakoid disk

81 PSII PSI ATP Synthase stroma ETC Thylakoid interior

82 Chloroplast

83 A C E D B

84 A C E D B


86 F E D G C H B A

87 Summary: From Leaf to Molecules Photosynthesis: The Movie Processes: Photosynthesis: The MoviePhotosynthesis: The MovieProcesses: Photosynthesis: The Movie

88 What runs the LDR? What runs the LIR?

89 What runs the LDR? sunlight What runs the LIR? ATP and NADPH

90 Overview of Photosynthesis

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