nutrition in plants

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  • nutrition in plants

    1. 1. Nutrition in Plants
    2. 2. How does trees on the fertile plain obtain their nutrients ? Or the algae in the sea ? Or the cacti in the desserts ?
    3. 3. Review Question <ul><li>Which mode of nutrition do the green plants carry out? </li></ul>A. Autotrophic nutrition B. Heterotrophic nutrition
    4. 4. Sorry! You’re wrong! <ul><li>Heterotrophic nutrition is the mode of nutrition in which organisms have to depend on other organisms or dead organic matters as their food sources. Green plants, however, can make organic food by themselves using simple inorganic substances. </li></ul>
    5. 5. Very Good! <ul><li>Autotrophic nutrition is the mode of nutrition in which organisms can make organic food by themselves using simple inorganic substances . </li></ul><ul><li>The process by which the green plants obtain nutrients is called : </li></ul><ul><li>Photosynthesis </li></ul>
    6. 6. Nature of photosynthesis <ul><li>Takes place in Chloroplast </li></ul><ul><li>Necessary factors : </li></ul><ul><ul><li>Carbon dioxide </li></ul></ul><ul><ul><li>Water </li></ul></ul><ul><ul><li>Sunlight </li></ul></ul><ul><ul><li>Chlorophyll </li></ul></ul>
    7. 7. Route of Carbon Dioxide for Photosynthesis
    8. 8. CO 2 Stoma Air Space Spongy Mesophyll Cell Chloroplast
    9. 9. CO 2 Chloroplast Palisade Mesophyll Cell Stoma Air Space
    10. 10. <ul><li>Light energy is trapped by chlorophyll in chloroplast </li></ul><ul><li>Light energy absorbed by chlorophyll splits water molecules into hydrogen and oxygen </li></ul><ul><li>Oxygen is released as a gas through stoma to outside </li></ul><ul><li>Hydrogen is fed into dark reaction </li></ul>Light reaction
    11. 11. 6 blue red % of light absorbed by chlorophyll green
    12. 12. Oxygen is produce as the by-product of photosynthesis.
    13. 13. Dark reaction <ul><li>No light is required ; can take place either in light or darkness </li></ul><ul><li>Hydrogen produced in light reaction combines with CO 2 to form carbohydrates </li></ul><ul><li>Water is formed as a by-product </li></ul>
    14. 14. Dark Reaction H Summary of Photosynthesis Water Oxygen Glucose ( C 6 H 12 O 6 ) Light Reaction 6 CO 2 + 6 H 2 0 C 6 H 12 O 6 + 6 O 2 Light Carbon Dioxide
    15. 15. Fate of carbohydrate products in the plant
    16. 16. carbohydrates (e.g. glucose) carbon dioxide and water release energy by respiration photosynthesis
    17. 17. convert into starch for storage because glucose is not a very good storage molecule carbohydrates (e.g. glucose) carbon dioxide and water photosynthesis
    18. 18. change into sucrose and is transported to other parts through phloem carbohydrates (e.g. glucose) carbon dioxide and water photosynthesis
    19. 19. carbon dioxide and water photosynthesis carbohydrates (e.g. glucose) combine to form fats and oils to form cell membranes and as a food store fatty acids glycerol
    20. 20. carbon dioxide and water photosynthesis carbohydrates (e.g. glucose) mineral salts from soil (e.g. NO 3 - , SO 4 2- ) amino acids join together to become protein molecules
    21. 21. Experiments on photosynthesis
    22. 22. Destarching <ul><li>Reason: </li></ul><ul><ul><li>To avoid any existing starch in the leaves interfering with the result , and to show that any starch found after the experiment is produced during the period of investigation </li></ul></ul><ul><li>Method: </li></ul><ul><ul><li>By placing the plant in dark for at least 48 hours </li></ul></ul>
    23. 23. To test a leaf for the presence of Starch Investigation 8.1
    24. 24. Why is the leaf first boiled in water ? Ans: Because the process can soften the leaf, break down the cuticle and kill the leaf. boiling water turn off Bunsen burner boiling alcohol hot water iodine white tile turn off Bunsen burner
    25. 25. Why is the leaf then boiled in alcohol ? Ans: To decolourize the leaf (to remove chlorophyll). boiling water turn off Bunsen burner boiling alcohol hot water iodine white tile turn off Bunsen burner
    26. 26. Why is it important to turn off the Bunsen burner when you are heating the alcohol ? Ans: Because alcohol catches fire easily. boiling water turn off Bunsen burner boiling alcohol hot water iodine white tile turn off Bunsen burner
    27. 27. Why is the leaf put in hot water after being boiled in alcohol ? Ans: Since the leaf becomes brittle after boiling in alcohol, so dipping it into hot water enables it to be softened. boiling water turn off Bunsen burner boiling alcohol hot water iodine white tile turn off Bunsen burner
    28. 28. What colour change can be observed if starch is present ? Ans: The leaf becomes blue-black when iodine solution is added to it. boiling water turn off Bunsen burner boiling alcohol hot water iodine white tile turn off Bunsen burner
    29. 29. To show that Chlorophyll is necessary for Photosynthesis Investigation 8.3
    30. 30. Which part of the leaf turns blue-black when treated with iodine solution ? Ans: Only the green part. green part purple part
    31. 31. Is chlorophyll necessary for photosynthesis ? Ans: Yes. green part purple part
    32. 32. What is the control in this experiment ? Ans: The green part of the leaf acts as the control. green part purple part
    33. 33. To show that Carbon Dioxide is necessary for Photosynthesis Investigation 8.4
    34. 34. Why is potassium hydroxide solution put in one of the flasks ? Ans: To absorb all the carbon dioxide in flask B. sunlight B A water potassium hydroxide solution
    35. 35. What happens to each leaf after testing the presence of starch at the end of the experiment ? Ans: The leaf in flask A changes to blue-black while the leaf in flask B stains brown. sunlight B A water potassium hydroxide solution
    36. 36. What do your results suggest about the relationship between carbon dioxide and photosynthesis ? Ans: Carbon dioxide is necessary for photosynthesis. sunlight B A water potassium hydroxide solution
    37. 37. Factors affecting the rate of photosynthesis
    38. 38. <ul><li> Light intensity </li></ul><ul><li> Rate of Photosynthesis </li></ul>Light Intensity
    39. 39. <ul><li> Carbon dioxide concentration </li></ul><ul><li> Rate of Photosynthesis </li></ul>Carbon Dioxide Concentration
    40. 40. <ul><li> Temperature </li></ul><ul><li> Rate of Photosynthesis </li></ul>Temperature Temperature > 40 ℃ Rate  & Stop soon
    41. 41. <ul><li>If no water, stomata close </li></ul><ul><li>no gaseous exchange </li></ul><ul><li>photosynthesis ceases </li></ul>Water Supply
    42. 42. Why is Photosynthesis important ? Green plants: the only organisms capable of trapping light to manufacture food from simple inorganic substances
    43. 43. Why is Photosynthesis important ? <ul><ul><li>Green plants(producers) starts the food chain & provide food for other organisms </li></ul></ul>
    44. 44. Why is Photosynthesis important ? <ul><ul><li>Atmospheric carbon dioxide is absorbed & oxygen is released into the atmosphere which maintains the composition of the atmosphere constant </li></ul></ul>
    45. 45. Parts of plant where photosynthesis takes place <ul><li>Mainly in the leaf because </li></ul><ul><ul><li>it contains a lot of chloroplasts </li></ul></ul><ul><ul><li>it is well adapted for performing photosynthesis </li></ul></ul>
    46. 46. Internal Structure of Leaf
    47. 47. cuticle upper epidermis palisade mesophyll spongy mesophyll intercellular space (air space) guard cell lower epidermis cuticle stoma chloroplasts
    48. 48. Cross-section of a leaf of dicotyledon
    49. 49. upper epidermis protect internal tissues from mechanical damage and bacterial & fungal invasion
    50. 50. Cuticle <ul><li>a waxy layer </li></ul><ul><li>prevent water loss from the leaf surface </li></ul><ul><li>protect the leaf </li></ul>
    51. 51. mesophyll
    52. 52. palisade mesophyll (layer) columnar cells closely packed together  absorb light more efficiently contains many chloroplasts
    53. 53. spongy mesophyll (layer) irregular cells loosely packed together to leave numerous large air spaces  allow rapid diffusion of gases throughout the leaf some (fewer than palisade mesophyll) chloroplasts for photosynthesis
    54. 54. lower epidermis same as upper epidermis except the cuticle is thinner
    55. 55. stoma (stomata) opening which allows gases to pass through it to go into or out of the leaf
    56. 56. guard cells control the size of stoma
    57. 57. Stoma stoma Guard cells thinner outer wall thicker inner wall
    58. 58. vascular bundle ( vein )
    59. 59. Internal Structure of Leaf xylem phloem
    60. 60. <ul><li>xylem </li></ul><ul><li>to transport water and mineral salts </li></ul><ul><li>towards the leaf </li></ul><ul><li>for mechanical support </li></ul>
    61. 61. <ul><li>phloem </li></ul><ul><li>to transport organic substances ( food/sugar/ glucose/ sucrose ) away from the leaf </li></ul>
    62. 62. Adaptation of leaf to photosynthesis
    63. 63. The leaf is thin decrease diffusion distance for gases & light The leaf is broad & flattened increase surface area to absorb more sunlight
    64. 64. Cuticle exists in upper epidermis and is transparent Allows most light to pass into photosynthetic mesophyll tissues
    65. 65. Palisade mesophyll cells are closely packed and contain many chloroplasts To carry out photosynthesis more efficiently
    66. 66. Spongy mesophyll cells are loosely packed with numerous large air spaces To allow rapid diffusion of gases throughout the leaf
    67. 67. Numerous stoma ta on lower epidermis To allow rapid gaseous exchange with the atmosphere
    68. 68. <ul><li>Extensive vein system </li></ul><ul><li>Allow sufficient water to reach the cells in the leaf </li></ul><ul><li>To carry food away to other parts of the plant </li></ul>
    69. 69. Mineral requirements in plants <ul><li>In order to synthesize amino acids, nitrate ions which must be taken into the plant from the soil through the root </li></ul><ul><li>Other minerals are also necessary to maintain the life of the plant (N, Mg, P, K, S, etc) </li></ul>
    70. 70. The importance of nitrogen <ul><li>For synthesis of proteins, chlorophyll, etc </li></ul><ul><li>Taken in form of nitrate ions </li></ul><ul><li>Deficiency symptoms: </li></ul><ul><ul><li>Little growth ( - no protein made) </li></ul></ul><ul><ul><li>Yellowing of leaves ( - no chlorophyll made) </li></ul></ul>
    71. 71. The importance of magnesium <ul><li>Essential component of chlorophyll </li></ul><ul><li>Deficiency symptoms: </li></ul><ul><ul><li>Yellowing of leaves (no chlorophyll made) </li></ul></ul><ul><ul><li>Poor growth (no food manufactured because of lack of chlorophyll) </li></ul></ul>
    72. 72. Use of fertilizers in agriculture <ul><li>Continuous harvesting crops removes valuable mineral salts from soil </li></ul><ul><li> Fertilizers are added to replace such loss </li></ul><ul><li>Two kinds of fertilizers: </li></ul><ul><ul><li>Natural fertilizers </li></ul></ul><ul><ul><li>Chemical fertilizers </li></ul></ul>
    73. 73. Natural fertilizers <ul><li>From manure </li></ul><ul><li>Organic compounds in it are decomposed by the bacteria in soil to form mineral salts </li></ul>
    74. 74. Chemical fertilizers <ul><li>Mainly nitrogenous and phosphorous compounds manufactured artificially </li></ul>
    75. 75. Comparison between natural and chemical fertilizers Natural fertilizers Chemical fertilizers Contain humus which can improve soil texture No humus so cannot improve soil texture Less soluble in water so less likely to be washed away Very soluble in water so more likely to be washed away
    76. 76. Comparison between natural and chemical fertilizers Natural fertilizers Chemical fertilizers Less soluble in water so more difficult to be absorbed Very soluble in water so easier to be absorbed More readily to be used by the plants Time is needed for the decomposition to complete before nutrients are available to plants Very expensive Much cheaper
    77. 77. ~ END ~

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