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Photosynthesis Using Light to Make Food
 
Chemical Equation for Photosynthesis
3 Main parts to a Plant <ul><li>Roots </li></ul><ul><li>Anchor’s the plant </li></ul><ul><li>Absorption of water and miner...
Remember what  plants   need… <ul><li>Photosynthesis  </li></ul><ul><ul><li>light reactions </li></ul></ul><ul><ul><ul><li...
Our Focus will be on the leaf
III.  Cross section of Leaf <ul><li>Cuticle  thin wax coating on upper epidermis helps protect against excessive water los...
II.  Cross section of Leaf  (continued) <ul><li>5.  Veins (xylem/phloem)   </li></ul><ul><ul><li>xylem :  carries water an...
Leaf Structure H 2 O CO 2 O 2 H 2 O O 2 CO 2 Transpiration vascular bundle phloem (sugar) xylem (water) stomate guard cell...
Photosynthesis <ul><li>The process by which plants, autotrophic protists and some bacteria use light energy to make sugars...
Heterotrophs <ul><li>Heterotroph   </li></ul><ul><li>Hetero  means other or different,  trophos means feed </li></ul><ul><...
Autotrophs <ul><li>Autotroph </li></ul><ul><li>From  autos , self, and  trophos , feed </li></ul><ul><li>produce their own...
Autotrophs <ul><li>Plants are  photo autotrophs because they use light as a source of energy </li></ul><ul><li>Some autotr...
Leaves and Photosynthesis
Chloroplasts <ul><li>Are the sites of photosynthesis in plants </li></ul><ul><li>The leaves are the major sites of photosy...
Chloroplasts <ul><li>Mesophyll  – the tissue in the interior of the leaf </li></ul><ul><li>Stomata  – microscopic pores in...
Inside a Mesophyll Cell
Inside a Chloroplast <ul><li>Three Parts </li></ul><ul><li>Thylakoid  – saclike photosynthetic membranes (chlorophyll resi...
Chloroplast – the Photosynthetic Organelle in Plant Cells
The Basics of Photosynthesis <ul><li>Overall equation: </li></ul><ul><ul><li>6CO 2  + 12H 2 0 + light energy  ->  C 6 H 12...
Two Stages of Photosynthesis <ul><li>1.  Light Reaction  (during day-time only, using light energy in the thylakoid membra...
1.  Light Reaction  (Light Dependent Reaction) <ul><li>occurs only during the daylight using light energy.  </li></ul><ul>...
Light <ul><li>Photon = a discrete packet of light energy.  </li></ul><ul><li>The shorter the wavelength, the greater the e...
Light & Pigment <ul><li>White light is actually a mixture of different wavelengths of light. </li></ul><ul><li>Plants gath...
Light Reactions: A Closer Look <ul><li>Light is absorbed by the pigments in the leaf </li></ul><ul><ul><li>chlorophyll  a ...
So why are leaves green? <ul><li>Look at the wavelengths of light that chlorophyll absorbs & uses in photosynthesis </li><...
 
Photosynthetic Pigments
Check for understanding… <ul><li>Would a plant grow well in green light? Explain! </li></ul>
Photosystems <ul><li>The pigments within the chloroplast are organized into ‘ photosystems’ </li></ul><ul><ul><ul><li>Ligh...
Photosystems
Photosystems <ul><li>There are 2 Photosystems (Photosystem I and Photosystem II  </li></ul><ul><ul><ul><ul><li>Both have  ...
Organization of a Thylakoid
Light Reaction (Light Dependent Reaction)
Photosystem II <ul><li>Takes place in thylakoid membrane </li></ul><ul><li>PS II captures light energy in the  680nm  rang...
Photosystem I <ul><li>Takes place in thylakoid membrane </li></ul><ul><li>In Photosystem I,  chlorophyll a  molecule, abso...
 
 
<ul><li>Sometimes Called the Calvin Cycle </li></ul><ul><li>Occurs in the  stroma  of chloroplast </li></ul><ul><li>Does n...
The Dark Reaction <ul><li>Uses the enzyme ribulose-1,5-bisphosphate carboxylase (Rubisco for short) to convert CO 2  into ...
Importance G3P <ul><li>G3P (glyceraldehyde-3-phosphate) can be converted to many other molecules </li></ul><ul><li>The hyd...
Glucose (C 6 H 12 O 6 ) <ul><li>Because one turn through the Dark Reaction produces  ONE  G3P (3 carbon molecule) Glucose ...
Light Independent Reactions: Sugar Synthesis
The Reactions of Photosynthesis
Light and Dark Reactions of Photosynthesis
Factors Affecting the Rate of Photosynthesis <ul><li>1.)  Increasing the level of CO 2 .   </li></ul><ul><li>2.)  Limiting...
Increasing the level of CO 2 .
Temperatures changes effect on  the rate of photosynthesis .
Increasing light intensity.
C 4  Photosynthesis <ul><li>In hot, dry climates </li></ul><ul><ul><li>Stomata must close to avoid wilting </li></ul></ul>...
Chloroplast distribution in C 4  vs. C 3  Plants
CO 2  Fixation in C 4  vs. C 3  Plants
CAM Photosynthesis <ul><ul><li>CAM plants partition carbon fixation by time </li></ul></ul><ul><ul><ul><li>During the nigh...
CO 2  Fixation in a CAM Plant
Climatic Adaptation: Photosynthesis <ul><li>Each method of photosynthesis has </li></ul><ul><li>advantages and disadvantag...
 
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Pre IB Biology Photosynthesis

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Transcript of "Pre IB Biology Photosynthesis"

  1. 1. Photosynthesis Using Light to Make Food
  2. 3. Chemical Equation for Photosynthesis
  3. 4. 3 Main parts to a Plant <ul><li>Roots </li></ul><ul><li>Anchor’s the plant </li></ul><ul><li>Absorption of water and minerals </li></ul><ul><li>II. Stem </li></ul><ul><li>Support plant and storage of food and water </li></ul><ul><li>III. Leaf </li></ul>
  4. 5. Remember what plants need… <ul><li>Photosynthesis </li></ul><ul><ul><li>light reactions </li></ul></ul><ul><ul><ul><li>light </li></ul></ul></ul><ul><ul><ul><li>H 2 O </li></ul></ul></ul><ul><ul><li>Calvin cycle </li></ul></ul><ul><ul><ul><li>CO 2 </li></ul></ul></ul>What structures have plants evolved to supply these needs?  sun  ground  air
  5. 6. Our Focus will be on the leaf
  6. 7. III. Cross section of Leaf <ul><li>Cuticle thin wax coating on upper epidermis helps protect against excessive water loss </li></ul><ul><li>Epidermis aids the cuticle in its function </li></ul><ul><li>Palisade mesophyll layer below the epidermis contains many chloroplasts and carries on most plant photosynthesis </li></ul><ul><li>Spongy mesophyll layer exchange and circulation of gases and water </li></ul>
  7. 8. II. Cross section of Leaf (continued) <ul><li>5. Veins (xylem/phloem) </li></ul><ul><ul><li>xylem : carries water and minerals upward to leaf cells from the stem and roots. </li></ul></ul><ul><ul><li>phloem: carries food made in the leaves down to the stem and the roots for use and storage. </li></ul></ul><ul><li>6. Stomata tiny openings exchange gases and water with the atmosphere. </li></ul><ul><li>7. Guard Cell one on each side of the stomata to regulate its opening and closing . </li></ul>
  8. 9. Leaf Structure H 2 O CO 2 O 2 H 2 O O 2 CO 2 Transpiration vascular bundle phloem (sugar) xylem (water) stomate guard cell palisades layer spongy layer cuticle epidermis
  9. 10. Photosynthesis <ul><li>The process by which plants, autotrophic protists and some bacteria use light energy to make sugars and other organic food molecules from carbon dioxide and water </li></ul>
  10. 11. Heterotrophs <ul><li>Heterotroph </li></ul><ul><li>Hetero means other or different, trophos means feed </li></ul><ul><li>Obtain their nutrients by eating other organisms </li></ul><ul><li>A.K.A. Consumers </li></ul>
  11. 12. Autotrophs <ul><li>Autotroph </li></ul><ul><li>From autos , self, and trophos , feed </li></ul><ul><li>produce their own organic molecules from CO 2 and other inorganic raw materials from the environment </li></ul><ul><li>A.K.A. Producers </li></ul>
  12. 13. Autotrophs <ul><li>Plants are photo autotrophs because they use light as a source of energy </li></ul><ul><li>Some autotrophs are chemo autotrophs which obtain their energy from inorganic substances, such as sulfur or ammonia </li></ul>
  13. 14. Leaves and Photosynthesis
  14. 15. Chloroplasts <ul><li>Are the sites of photosynthesis in plants </li></ul><ul><li>The leaves are the major sites of photosynthesis, with about ½ million chloroplasts per square millimeter </li></ul><ul><li>Chlorophyll is the green pigment in the chloroplasts </li></ul><ul><li>Chloroplasts are mainly found in the mesophyll of the leaf </li></ul>
  15. 16. Chloroplasts <ul><li>Mesophyll – the tissue in the interior of the leaf </li></ul><ul><li>Stomata – microscopic pores in the surface of the leave (carbon dioxide enters, oxygen exits) </li></ul>
  16. 17. Inside a Mesophyll Cell
  17. 18. Inside a Chloroplast <ul><li>Three Parts </li></ul><ul><li>Thylakoid – saclike photosynthetic membranes (chlorophyll resides here) </li></ul><ul><li>Grana – stacks of thylakoids </li></ul><ul><li>Stroma – space outside the thylakoids </li></ul>
  18. 19. Chloroplast – the Photosynthetic Organelle in Plant Cells
  19. 20. The Basics of Photosynthesis <ul><li>Overall equation: </li></ul><ul><ul><li>6CO 2 + 12H 2 0 + light energy -> C 6 H 12 O 6 + 6O 2 + 6H 2 O </li></ul></ul><ul><li>The carbohydrate C 6 H 12 O 6 is glucose </li></ul><ul><li>Water is on both sides of the equation because some is consumed & some is produced </li></ul><ul><li>Simplified equation: </li></ul><ul><ul><li>6CO 2 + 6H 2 0 + light energy -> C 6 H 12 O 6 + 6O 2 </li></ul></ul>
  20. 21. Two Stages of Photosynthesis <ul><li>1. Light Reaction (during day-time only, using light energy in the thylakoid membrane) </li></ul><ul><li>2. Dark Reaction (Calvin Cycle ) (both day and night, in the stroma), which are linked </li></ul><ul><li>together by NADPH and ATP. </li></ul>
  21. 22. 1. Light Reaction (Light Dependent Reaction) <ul><li>occurs only during the daylight using light energy. </li></ul><ul><li>takes place in the thylakoid membrane. </li></ul><ul><li>splits water to produce oxygen </li></ul><ul><li>production small amounts of ATP </li></ul><ul><li>reduction of NADP + to NADPH </li></ul>
  22. 23. Light <ul><li>Photon = a discrete packet of light energy. </li></ul><ul><li>The shorter the wavelength, the greater the energy….and vice-versa. </li></ul>
  23. 24. Light & Pigment <ul><li>White light is actually a mixture of different wavelengths of light. </li></ul><ul><li>Plants gather the sun’s energy with light absorbing molecules called PIGMENTS . </li></ul><ul><li>The plant’s principle pigment is chlorophyll and there are 2 main types: “a” and “b.” </li></ul><ul><ul><li>Plants also contain red and orange pigments such as carotene which absorbs light in other areas of the spectrum. </li></ul></ul><ul><li>Energy absorbed by chlorophyll is transferred directly to electrons in the chlorophyll molecule. These high energy electrons make photosynthesis work. </li></ul>
  24. 25. Light Reactions: A Closer Look <ul><li>Light is absorbed by the pigments in the leaf </li></ul><ul><ul><li>chlorophyll a (blue-green) – primary pigment involved in the light reactions </li></ul></ul><ul><ul><li>chlorophyll b (yellow-green) – an accessory pigment </li></ul></ul><ul><ul><li>carotenoids (yellow and orange) – other accessory pigments </li></ul></ul>
  25. 26. So why are leaves green? <ul><li>Look at the wavelengths of light that chlorophyll absorbs & uses in photosynthesis </li></ul><ul><li>The colors that are left are reflected back and that is what you see. </li></ul>
  26. 28. Photosynthetic Pigments
  27. 29. Check for understanding… <ul><li>Would a plant grow well in green light? Explain! </li></ul>
  28. 30. Photosystems <ul><li>The pigments within the chloroplast are organized into ‘ photosystems’ </li></ul><ul><ul><ul><li>Light is gathered using hundreds of chlorophyll a, chlorophyll b , and carotenoids molecules </li></ul></ul></ul><ul><ul><ul><li>These pigments capture, and harness the light from the sun </li></ul></ul></ul>Light Reactions: A Closer Look
  29. 31. Photosystems
  30. 32. Photosystems <ul><li>There are 2 Photosystems (Photosystem I and Photosystem II </li></ul><ul><ul><ul><ul><li>Both have Chlorophyll A molecule and primary electron acceptor </li></ul></ul></ul></ul><ul><li>End product of each is different </li></ul><ul><ul><ul><li>Photosystem II generates ATP </li></ul></ul></ul><ul><ul><ul><li>Photosystem I generates NADPH + </li></ul></ul></ul><ul><li>The products of each are used to drive the Calvin Cycle </li></ul>
  31. 33. Organization of a Thylakoid
  32. 34. Light Reaction (Light Dependent Reaction)
  33. 35. Photosystem II <ul><li>Takes place in thylakoid membrane </li></ul><ul><li>PS II captures light energy in the 680nm range </li></ul><ul><li>Causes an electron to be ejected from the reaction center ( chlorophyll a ) </li></ul><ul><ul><li>Electron travels down electron transport chain to PS I </li></ul></ul><ul><ul><li>The Electron will be replaced with an electron from water </li></ul></ul><ul><ul><li>Water splits into H + and O 2 . The H + concentrate build inside the thylakoid chambers and O 2 to be released as a waste product </li></ul></ul><ul><ul><li>Which causes ATP production </li></ul></ul>
  34. 36. Photosystem I <ul><li>Takes place in thylakoid membrane </li></ul><ul><li>In Photosystem I, chlorophyll a molecule, absorbs light of 700 nanometers wavelength (red light). </li></ul><ul><li>PS I captures light energy and ejects an electron </li></ul><ul><ul><li>Transferred permanently to a molecule of NADP + </li></ul></ul><ul><ul><li>Causes NADPH production </li></ul></ul>
  35. 39. <ul><li>Sometimes Called the Calvin Cycle </li></ul><ul><li>Occurs in the stroma of chloroplast </li></ul><ul><li>Does not require light. </li></ul><ul><li>Carbon enters the Dark Reaction in the form of CO 2 and leaves in the form of sugar </li></ul><ul><li>ATP is used as an energy source </li></ul><ul><li>NADPH is used to add high-energy electrons to make the sugar </li></ul><ul><li>A 3-carbon sugar is produced: glyceraldehyde-3-phosphate (G3P) </li></ul>2. Dark Reaction/light independent reaction
  36. 40. The Dark Reaction <ul><li>Uses the enzyme ribulose-1,5-bisphosphate carboxylase (Rubisco for short) to convert CO 2 into the 3 Carbon Sugar G3P </li></ul><ul><li>Several intermediate Carbon sugars are formed and rearranged before G3P is made </li></ul><ul><li>Rubisco is ALWAYS conserved (remade) </li></ul><ul><ul><li>Input : CO 2 , ATP, and NADPH. </li></ul></ul><ul><ul><li>Output : Sugars, ADP, and NADP+. </li></ul></ul>
  37. 41. Importance G3P <ul><li>G3P (glyceraldehyde-3-phosphate) can be converted to many other molecules </li></ul><ul><li>The hydrocarbon skeleton of G3P can form </li></ul><ul><ul><ul><ul><li>Fatty acids and glycerol to make plant oils </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Glucose phosphate (simple sugar) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Fructose (which with glucose = sucrose) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Starch and cellulose </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Amino acids </li></ul></ul></ul></ul>
  38. 42. Glucose (C 6 H 12 O 6 ) <ul><li>Because one turn through the Dark Reaction produces ONE G3P (3 carbon molecule) Glucose requires TWO trips around the Dark Reaction </li></ul><ul><ul><ul><ul><ul><li>6 Carbon dioxide </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>18 molecules of ATP </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>12 molecules of NADPH </li></ul></ul></ul></ul></ul>
  39. 43. Light Independent Reactions: Sugar Synthesis
  40. 44. The Reactions of Photosynthesis
  41. 45. Light and Dark Reactions of Photosynthesis
  42. 46. Factors Affecting the Rate of Photosynthesis <ul><li>1.) Increasing the level of CO 2 . </li></ul><ul><li>2.) Limiting the amount of water . </li></ul><ul><li>3.) Temperature’s between 0C to 35C. </li></ul><ul><li>4.) Temperatures over 35C will decrease </li></ul><ul><li>the rate of photosynthesis. </li></ul><ul><li>5.) Increasing light intensity. </li></ul>
  43. 47. Increasing the level of CO 2 .
  44. 48. Temperatures changes effect on the rate of photosynthesis .
  45. 49. Increasing light intensity.
  46. 50. C 4 Photosynthesis <ul><li>In hot, dry climates </li></ul><ul><ul><li>Stomata must close to avoid wilting </li></ul></ul><ul><ul><li>CO 2 decreases and O 2 increases </li></ul></ul><ul><ul><li>O 2 starts combining with RuBP instead of CO 2 </li></ul></ul><ul><li>In C 4 plants </li></ul><ul><ul><li>Fix CO 2 to PEP a C 3 molecule </li></ul></ul><ul><ul><li>The result is oxaloacetate, a C 4 molecule </li></ul></ul><ul><ul><li>In hot & dry climates </li></ul></ul><ul><ul><ul><li>Net productivity about 2-3 times C 3 plants </li></ul></ul></ul><ul><ul><li>In cool, moist, can’t compete with C 3 </li></ul></ul>
  47. 51. Chloroplast distribution in C 4 vs. C 3 Plants
  48. 52. CO 2 Fixation in C 4 vs. C 3 Plants
  49. 53. CAM Photosynthesis <ul><ul><li>CAM plants partition carbon fixation by time </li></ul></ul><ul><ul><ul><li>During the night </li></ul></ul></ul><ul><ul><ul><ul><li>CAM plants fix CO 2 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Forms C 4 molecules, </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Stored in large vacuoles </li></ul></ul></ul></ul><ul><ul><ul><li>During daylight </li></ul></ul></ul><ul><ul><ul><ul><li>NADPH and ATP are available </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Stomata closed for water conservation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>C 4 molecules release CO 2 to Calvin cycle </li></ul></ul></ul></ul>
  50. 54. CO 2 Fixation in a CAM Plant
  51. 55. Climatic Adaptation: Photosynthesis <ul><li>Each method of photosynthesis has </li></ul><ul><li>advantages and disadvantages </li></ul><ul><li>Depends on the climate </li></ul><ul><ul><ul><li>C 4 plants most adapted to: </li></ul></ul></ul><ul><ul><ul><ul><li>high light intensities </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>high temperatures </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Limited rainfall </li></ul></ul></ul></ul></ul><ul><ul><ul><li>C 3 plants better adapted to </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Cold (below 25C) </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>High moisture </li></ul></ul></ul></ul></ul><ul><ul><ul><li>CAM plants better adapted to extreme aridity </li></ul></ul></ul><ul><ul><ul><ul><li>CAM occurs in 23 families of flowering plants </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Also found among nonflowering plants </li></ul></ul></ul></ul>

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