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Nutrition in plants

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Nutrition in Plants. Notes reorganized from LPK TB

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Nutrition in plants

  1. 1. Nutrition in plants (I) Chapter 7
  2. 2. Learning Objectives <ul><li>Part I </li></ul><ul><li>Why is photosynthesis important? Pg 127 </li></ul><ul><li>Photosynthesis overall Equation pg 120 </li></ul><ul><li>Fate of glucose formed pg 125-126 </li></ul><ul><li>Leaf structure & function Chap 7.2 pg 128-130 </li></ul><ul><li>How do CO 2 & H 2 O enter the plant? pg132 </li></ul><ul><li>What are the conditions necessary for photosynthesis? Pg 118 </li></ul><ul><li>Part II </li></ul><ul><li>Testing for starch investigation 7.1 </li></ul><ul><li>Factors affecting the rate of photosynthesis (ICT) pg 123-124 </li></ul><ul><li>Limiting factors pg 121 </li></ul>
  3. 3. Why is photosynthesis important? <ul><li>C onverts light to chemical energy </li></ul><ul><li>“ P urifies” air </li></ul><ul><li>F ossil fuel: Coal </li></ul>7.1 pg 127 Why photosynthesis? <ul><ul><ul><ul><li>Sunlight is the ultimate source of energy </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Light  chemical energy stored as carbohydrate </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Proteins, fats and other organic compounds can be derived from carbohydrates </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Removes CO2; </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Provides O2 for cellular respiration </li></ul></ul></ul></ul><ul><li>Coal formed from dead plant matter over 400 MYA </li></ul>
  4. 4. Photosynthesis <ul><li>Photosynthesis is the process by which light energy absorbed by chlorophyll is transformed into chemical energy used to make carbohydrates from water & carbon dioxide. Oxygen is released during the process. </li></ul>7.1 pg 119 What is photosynthesis?
  5. 5. Photosynthesis <ul><li>Photosynthesis consists of </li></ul><ul><li>2 stages: </li></ul><ul><li>Light stage </li></ul><ul><li>Light independent stage </li></ul>7.1 pg 119 What is photosynthesis?
  6. 6. Light stage of photosynthesis <ul><li>Light energy is absorbed by chlorophyll and converted into chemical energy. </li></ul><ul><li>Light energy used for photolysis of water </li></ul><ul><li>Photolysis = light + spliting </li></ul><ul><li>12 H 2 O molecules spilt to yield 6 O 2 molecules + 24 H atoms </li></ul><ul><li>Glucose is the first stable form of carbohydrate formed. </li></ul>7.1 pg 119 What is photosynthesis? Q. Why does the volume of oxygen produced indicate the rate of photosynthesis?
  7. 7. Light-independent stage of Photosynthesis <ul><li>H atoms from light stage help reduce 6 carbon dioxide molecules to glucose. </li></ul>
  8. 8. Overall Equation for Photosynthesis 7.1 pg 120 Equation glucose Chlorophyll Word equation: Chemical equation:
  9. 9. Fate of glucose formed 7.1 pg 125-126 Fate of glucose Glucose Sucrose Energy Used Used Used Stored Starch Fats a.a Proteins Cellulose cell wall
  10. 10. Fate of glucose formed during photosynthesis <ul><li>Glucose is used </li></ul><ul><li>immediately for Energy via respiration </li></ul><ul><li>To make cell wall </li></ul><ul><li>To make fats </li></ul><ul><li>To make amino acids & proteins </li></ul>Use of glucose <ul><li>Glucose is first used by cells during tissue respiration to provide energy for cellular activity </li></ul><ul><li>Glucose react with nitrates & minerals to form amino acids . </li></ul><ul><li>Amino acids form proteins which are used to build new cell protoplasm . </li></ul><ul><li>In leaves & storage organs </li></ul>
  11. 11. Fate of glucose formed during photosynthesis <ul><li>Glucose can be stored as starch </li></ul><ul><li>Excess glucose  sucrose which is transported to storage organs e.g. stem tubers & root tubers . </li></ul>Storage of glucose <ul><li>Temporally stored as starch in leaf in the </li></ul><ul><li>day (high rate photosynthesis) </li></ul><ul><li>Starch is reconverted by enzymes into </li></ul><ul><li>glucose/sucrose at night </li></ul>
  12. 12. Leaf Structure & Function 7.2 pg 128 Leaf Structure & function
  13. 13. Leaf Structure 7.2 pg 128 Leaf Structure & function <ul><li>Lamina </li></ul><ul><li>Petiole (leaf stalk) </li></ul><ul><li>Upper epidermis </li></ul><ul><li>Mesophyll </li></ul><ul><li>a) palisade </li></ul><ul><li>b) spongy </li></ul><ul><li>Lower epidermis </li></ul><ul><li>Stoma </li></ul><ul><li>Vein network </li></ul><ul><li>Leaf arrangement </li></ul>Internal External
  14. 14. External Structure of Leaf
  15. 15. Internal Structure of Leaf
  16. 16. Internal Structure of Leaf Mesophyll Palisade mesophyll Spongy mesophyll
  17. 17. Upper Epidermis <ul><li>Cuticle </li></ul><ul><li>- Waxy </li></ul><ul><li>protects leaf tissue </li></ul><ul><li>prevents excessive water evaporation </li></ul><ul><li>Is transparent </li></ul><ul><li>1 layer of closely packed cells </li></ul>
  18. 18. Mesophyll <ul><li>Layer between upper and lower epidermis </li></ul><ul><li>Consists of </li></ul><ul><li>Irregular cells </li></ul><ul><li>Loosely packed; many intercellular air spaces </li></ul><ul><li>Fewer chloroplasts than palisade mesophyll cells </li></ul><ul><li>long, cylindrical cells </li></ul><ul><li>(1-2 layers) </li></ul><ul><li>closely packed </li></ul><ul><li>Cells here has many chloroplasts </li></ul>Spongy Mesophyll Palisade Mesophyll
  19. 19. Mesophyll cells <ul><li>All mesophyll cells have a thin film of moisture for </li></ul><ul><li>CO 2 to dissolve in </li></ul><ul><li>X ylem & P hloem found here. </li></ul><ul><li>X+ Y = vascular bundles (more in chap 9) </li></ul><ul><li>Xylem transports water & dissolved materials from roots to rest of plants </li></ul><ul><li>Phloem transports sugars from leaf to rest of plant </li></ul>
  20. 20. Lower Epidermis <ul><li>Similar to upper epidermis </li></ul><ul><li>Contains stomata </li></ul>
  21. 21. Leaf Structural adaptations to Function 7.2 pg 133 Leaf Structure to function Xylem transports water; phloem transports sugar Veins with xylem & phloem Rapid diffusion of gases Many intercellular air spaces More sunlight reaches top half of leaf More chloroplasts in upper palisade tissue Absorbs, converts light  chemical energy stored in glucose chloroplasts Gaseous exchange Stomata Reduce water loss due to evaporation Waxy cuticle Max absorption & penetration of light to reach mesophyll Max diffusion for CO2 Thin lamina Position leaf for max light absorption Petiole (leaf stalk) Function Structure
  22. 22. Q. How do CO 2 & H 2 O enters the leaf? <ul><li>Via stomata </li></ul><ul><li>Via roots  </li></ul><ul><li>Xylem  </li></ul><ul><li>Veins  </li></ul><ul><li>Cell to cell in leaf (osmosis) </li></ul>In the day, CO 2 is used for photosynthesis. The CO 2 concentration in leaf is lower than that of the atmosphere. CO 2 diffuses from surrounding air through stomata into leaf’s air spaces down a concentration gradient .
  23. 23. Q. What are the conditions necessary for photosynthesis? <ul><li>Sunlight </li></ul><ul><li>Chlorophyll (green pigment) </li></ul><ul><li>CO 2 </li></ul><ul><li>Water </li></ul><ul><li>Suitable temperature </li></ul>7.1 pg 118 Photosynthesis conditions Sunlight, Chlorophyll & CO2 are essential for photosynthesis. Other conditions needed are a suitable temperature and water.
  24. 24. Investigation on conditions necessary for photosynthesis 7.2-7.4 <ul><li>De starch 2 potted plants </li></ul><ul><li>Enclose pots & parts of plants excluding leaves in polythene bags; </li></ul><ul><li>Place 1 pot in bell jar with soda lime or KI; the other without </li></ul><ul><li>Expose plants in sunlight </li></ul><ul><li>Remove a leaf from each pot test for starch . </li></ul><ul><li>De starch variegated leaf </li></ul><ul><li>Expose leaf to sunlight for a few hours </li></ul><ul><li>Remove leaf; note parts with chlorophyll </li></ul><ul><li>Decolourise the leaf with ethanol </li></ul><ul><li>Test for starch </li></ul><ul><li>De starch </li></ul><ul><li>Remove leaf </li></ul><ul><li>Cover parts of leaf with black paper </li></ul><ul><li>Remove leaf after a few hours </li></ul><ul><li>Test for starch </li></ul>Exp 7.4 CO 2 Exp 7.3 Chlorophyll Exp 7.2 Sunlight
  25. 25. Q. Why do we test for starch as an indicator of photosynthesis? <ul><li>Excess glucose made by leaves are stored as starch </li></ul>Q. How do we “de-starch” plants? <ul><li>By placing the plant in darkness for 2 days. In darkness, no photosynthesis occurs. Glucose is used up for respiration. Some starch will be converted back to glucose for cellular respiration. </li></ul>
  26. 26. Summary <ul><li>Part I </li></ul><ul><li>Why is photosynthesis important? Pg 127 </li></ul><ul><li>Photosynthesis Overall Equation pg 120 </li></ul><ul><li>Fate of glucose formed pg 125-126 </li></ul><ul><li>Leaf structure & function Chap 7.2 pg 128-130 </li></ul><ul><li>How do CO 2 & H 2 O enter the plant? pg132 </li></ul><ul><li>What are the conditions necessary for photosynthesis? Pg 118 </li></ul><ul><li>Part II </li></ul><ul><li>Testing for starch investigation 7.1 </li></ul><ul><li>Factors affecting the rate of photosynthesis (ICT) pg 123-124 </li></ul><ul><li>Limiting factors pg 121 </li></ul>
  27. 27. Nutrition in plants (II) Chapter 7
  28. 28. Learning Objectives <ul><li>Part I </li></ul><ul><li>Why is photosynthesis important? Pg 127 </li></ul><ul><li>Photosynthesis overall Equation pg 120 </li></ul><ul><li>Fate of glucose formed pg 125-126 </li></ul><ul><li>Leaf structure & function Chap 7.2 pg 128-130 </li></ul><ul><li>How do CO 2 & H 2 O enter the plant? pg132 </li></ul><ul><li>What are the conditions necessary for photosynthesis? Pg 118 </li></ul><ul><li>Part II </li></ul><ul><li>Testing for starch investigation 7.1 </li></ul><ul><li>Factors affecting the rate of photosynthesis (ICT) pg 123-124 </li></ul><ul><li>Limiting factors pg 121 </li></ul>
  29. 29. Recap How do CO 2 & H 2 O enter the plant? pg132
  30. 30. Pathway of CO2 from atmosphere through Stomata to rest of the plant.
  31. 31. Recap: <ul><li>Pathway of water from roots through </li></ul><ul><li>plant & out of stomata </li></ul>
  32. 32. Starch Test (Recap of Activity 20.1 in sec 2 practical) <ul><li>How can we test for starch in a leaf? </li></ul><ul><li>Remove green leaf </li></ul><ul><li>Submerge leaf in boiling water for 2 min </li></ul><ul><li>Place leaf in ethanol in boiling tube in a hot water for 10minutes </li></ul><ul><li>Remove the leaf, dip it in hot water </li></ul><ul><li>add a few drops of iodine solution and test for starch </li></ul>We can show that photosynthesis has taken place by testing for presence of starch in leaves. 7.1 pg 115 Photosynthesis
  33. 33. Factors affecting Photosynthetic Rate <ul><li>-Light intensity </li></ul><ul><li>-temperature </li></ul><ul><li>Carbon dioxide concentration </li></ul><ul><li>Chlorophyll concentration </li></ul><ul><li>Water </li></ul><ul><li>pollution </li></ul>7.1 pg 123-124 Photosynthesis
  34. 34. Factors affecting Photosynthetic Rate <ul><li>Light intensity (investigation 7.6) </li></ul><ul><li>Q. How can we investigate the effect of different light intensities on the rate of photosynthesis? </li></ul>7.1 pg 123-124 Photosynthesis <ul><li>Set up apparatus </li></ul><ul><li>Allow plant to adapt till bubbles produced at a steady rate </li></ul><ul><li>Count bubbles over a period of 5 minutes. Repeat to get average </li></ul><ul><li>Repeat step 3 with different distance from light source. E.g. 10, 25, 50,75,100cm (shorter distance= higher intensity) </li></ul><ul><li>Record results in table. Plot rate of bubbling per min against distance between lamp & the plant. </li></ul><ul><li>Conclusion </li></ul>
  35. 35. Suggested Table 3.6 18.0 16 18 20 100 5 7.9 39.3 39 39 40 75 4 12.1 60.3 63 58 60 50 3 16.9 84.7 85 89 80 25 2 20.9 104.3 110 103 100 10 1 Rate of bubbles/min Aver-age 3 rd reading 2 nd reading 1st reading Distance of light source from plant (cm) Set up
  36. 36. As distance increases, light intensity decreases.
  37. 37. 0 B ▲ Fig 1 Effect of increasing light intensity on the rate of photosynthesis at 0.03% CO2 at 20°C From A to B, even though light intensity increases, rate of photosynthesis remains constant. Light intensity is no longer a limiting factor. From 0 to A, as light intensity increases, rate of photosynthesis increases. Light intensity is a limiting factor during this stage A
  38. 38. Factors affecting Photosynthetic Rate 7.1 pg 123-124 Photosynthesis Temperature (investigation 7.7) Q. How can we investigate the effect of different temperatures on the rate of photosynthesis? <ul><li>Set up </li></ul><ul><li>Place lamp (e.g. 60W) 10cm away from plant. Keep this distance constant. </li></ul><ul><li>Add ice-cube to make the water bath 5°C temperature. Allow plant to adapt till bubbles produced at a steady rate </li></ul><ul><li>Count bubbles over a period of 5 minutes. Repeat to get average </li></ul><ul><li>Repeat step 3 at different temperatures. E.g. 15 °C, 20°C, 35°C,50°C. Record results in table. Plot rate of bubbling per min against temperature. </li></ul><ul><li>Conclusion </li></ul>
  39. 39. Effect of increasing temperature on rate of photosynthesis <ul><li>a) As temperature increases, rate of photosynthesis increases </li></ul><ul><li>b) optimum temperature; max rate of photosynthesis </li></ul><ul><li>c) beyond point B, photosynthesis decreases as temperature increased </li></ul>
  40. 40. Carbon dioxide Concentration (investigation 7.8) Q. How can we investigate the effect of different carbon dioxide concentration on the rate of photosynthesis? Factors affecting Photosynthetic Rate <ul><li>Refer to TB pg124 investigation 7.8 for details of experiment </li></ul>
  41. 41. Limiting factors <ul><li>Any factor that directly affects a process if its quantity is changed. </li></ul><ul><li>Rate of photosynthesis is affected by: </li></ul><ul><li>Light intensity </li></ul><ul><li>temperature </li></ul><ul><li>CO 2 concentration </li></ul>7.1 pg 121 Photosynthesis
  42. 42. If there is not enough chairs , time taken will be longer.
  43. 43. If there are many chairs – time taken would still be the same as in the case of having 5 chairs only.
  44. 44. 0 B ▲ Fig 1 Effect of increasing light intensity on the rate of photosynthesis at 0.03% CO2 at 20°C From A to B, even though light intensity increases, rate of photosynthesis remains constant. Light intensity is no longer a limiting factor. From 0 to A, as light intensity increases, rate of photosynthesis increases. Light intensity is a limiting factor during this stage A Light intensity as a limiting factor
  45. 45. Effect of increasing temperature on the rate of photosynthesis Increasing light intensity (photons/m/s) Rate of photosynthesis (bubbles/min) Temperature as a limiting factor F E
  46. 46. <ul><li>As temperature increases, rate of photosynthesis increases significantly </li></ul><ul><li>From graph, every 10°C increase in temperature, rate of photosynthesis ≈ doubles. </li></ul><ul><li>Therefore temperature of surroundings is the limiting factor. </li></ul>Temperature as a limiting factor
  47. 47. Carbon dioxide concentration as a limiting factor D C
  48. 48. Carbon dioxide concentration as a limiting factor <ul><li>Usually CO2 is an important limiting factor in the atmosphere. </li></ul><ul><li>As CO2 increases, rate of photosynthesis significantly increases. </li></ul><ul><li>This indicates CO2 concentration is the limiting factor in CD. </li></ul>
  49. 49. Summary <ul><li>Part I </li></ul><ul><li>Why is photosynthesis important? Pg 127 </li></ul><ul><li>Photosynthesis overall Equation pg 120 </li></ul><ul><li>Fate of glucose formed pg 125-126 </li></ul><ul><li>Leaf structure & function Chap 7.2 pg 128-130 </li></ul><ul><li>How do CO 2 & H 2 O enter the plant? pg132 </li></ul><ul><li>What are the conditions necessary for photosynthesis? Pg 118 </li></ul><ul><li>Part II </li></ul><ul><li>Testing for starch investigation 7.1 </li></ul><ul><li>Factors affecting the rate of photosynthesis (ICT) pg 123-124 </li></ul><ul><li>Limiting factors pg 121 </li></ul>

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