GoConqr has a new look! Let us know what you think.

Sign up free

Flashcards

5A: Photosynthesis

Beth Tonks Biology A-Level English 87 cards

Cards in this deck (87)

  1. 1WHY IS ENERGY IMPORTANT?Plants and animals need energy for biological processes to occur
    Plants - photosynthesis, active transport, DNA replication, cell division and protein synthesis
    Animals - muscle contraction, maintenance of body temperature, active transport, DNA replication, cell division and protein synthesis.
  2. 2WHAT IS PHOTOSYNTHESIS?The process where energy from light is used to make glucose from water and carbon dioxide.
    The light energy is converted to chemical energy in the form of glucose
    Energy is stored in the glucose until the plants release it by respiration
  3. 3HOW DO ANIMALS OBTAIN GLUCOSE?By eating plants
    By eating animals which have eaten plants
    They then respire the glucose to release energy
  4. 4WHAT IS A METABOLIC PATHWAY?The process occurs in a series of small reactions controlled by enzymes
    e.g. photosynthesis
  5. 5COMPENSATION POINTThe level of light intensity at which the rate of photosynthesis exactly matches the rate of respiration.
    Both respiration and photosynthesis can occur at the same time and at different rates in plants.
    The rate at which photosynthesis takes place is partly dependent on the light intensity of the environment that the plant is in.
  6. 6HOW CAN YOU CALCULATE THE COMPENSATION POINT?Measure the rate at which oxygen or carbon dioxide is produced and used by a plant at different light intensities
    Photosynthesis produces oxygen and uses carbon dioxide, and respiration uses oxygen and produces carbon dioxide
    The compensation point will be the light intensity at which oxygen/carbon dioxide is being used as quickly as it is produced.
  7. 7WHERE DOES PHOTOSYNTHESIS TAKE PLACE?In the chloroplasts
  8. 8WHAT ARE CHLOROPLASTS?Chloroplasts are small, flattened organelles surrounded by a double membrane
  9. 9WHAT ARE GRANA?Thylakoids (fluid filled sacs) are stacked up in the chloroplasts into structures called grana
  10. 10WHAT LINKS THE GRANA?Bits of thylakoid membrane called lamellae (singular = lamella)
  11. 11WHAT ARE PHOTOSYNTHETIC PIGMENTS? WHERE ARE THEY FOUND?Coloured substances that absorb the light energy needed for photosynthesis
    Found in the thylakoid membranes in the chloroplasts attached to proteins
  12. 12WHAT IS A PHOTOSYSTEM?The photosynthetic pigment and protein
  13. 13WHAT ARE THE TWO PHOTOSYSTEMS USED BY PLANTS TO CAPTURE LIGHT ENERGY?Photosystem I (PSI) - absorbs light best at a wavelength of 700nm
    Photosystem II (PSII) - absorbs light best at 680 nm
  14. 14WHAT IS THE STROMA?A gel-like substance contained within the inner membrane of the chloroplasts and surrounding the thylakoids
    It contains enzymes, sugars and organic acids
    Carbohydrates produced by photosynthesis and not used straight away are stored as starch grains in the stroma
  15. 15WHAT ARE REDOX REACTIONS?Reactions that involve oxidation and reduction
    They occur in photosynthesis and respiration
  16. 16WHAT HAPPENS IF SOMETHING IS REDUCED?It has gained electrons
    May have gained hydrogen or lost oxygen
  17. 17WHAT HAPPENS IF SOMETHING IS OXIDISED?It has lost electrons
    May have lost hydrogen or gained oxygen
  18. 18WHAT DOES OXIDATION OF ONE MOLECULE ALWAYS INVOLVE?Reduction of another molecule
  19. 19WHAT IS A COENZYME?A molecule that aids the function of an enzyme
  20. 20HOW DO COENZYMES WORK?By transferring a chemical group from one molecule to another
  21. 21WHAT COENZYME IS USED IN PHOTOSYNTHESIS?NADP
    It transfers hydrogen from one molecule to another
    This means it can reduce (give hydrogen to) or oxidise (take hydrogen from) a molecule
  22. 22WHAT ARE THE TWO STAGES THAT MAKE UP PHOTOSYNTHESIS?The light dependent reaction
    The light independent reaction
  23. 23WHERE DOES THE LIGHT DEPENDENT REACTION HAPPEN?The thylakoid membranes of the chloroplasts
  24. 24THE LIGHT DEPENDENT REACTION: WHAT HAPPENS DURING PHOTOIONISATION?Light energy is absorbed by chlorophyll (and other photosynthetic pigments) in the photosystems
    The light energy excites the electrons in the chlorophyll, giving them more energy, which eventually causes them to be released from the chlorophyll molecule.
    The chlorophyll molecule is now a positively charged ion
  25. 25THE LIGHT DEPENDENT REACTION: WHAT IS SOME OF THE ENERGY FROM THE RELEASED ELECTRONS USED FOR?To add a phosphate group to ADP to form ATP - transfers energy
    To reduce NADP to form reduced NADP - transfers hydrogen to the light independent reaction
    During the process, water is oxidised to oxygen
  26. 26WHERE DOES THE LIGHT INDEPENDENT REACTION TAKE PLACE?The stroma of the chloroplast
  27. 27WHY DOES THE LIGHT INDEPENDENT REACTION RELY ON THE LIGHT DEPENDENT REACTION?The light independent reaction doesn't use light directly but does rely on the products of the light dependent reaction
  28. 28WHAT IS THE LIGHT INDEPENDENT REACTION ALSO KNOWN AS?The Calvin Cycle
  29. 29WHAT IS THE ENERGY RESULTING FROM THE PHOTOIONISATION OF CHLOROPHYLL IN THE LIGHT DEPENDENT REACTION USED FOR?Photophosphorylation - making ATP from ADP and inorganic phosphate
    Making reduced NADP from NADP
    Photolysis - splitting water into protons, electrons and oxygen
  30. 30WHAT IS PHOTOPHOSPHORYLATION?The process of adding phosphate to a molecule using light
  31. 31WHAT IS PHOTOLYSIS?The splitting (lysis) of a molecule using light (photo) energy
  32. 32WHAT TWO TYPES OF PHOTOPHOSPHORYLATION DOES THE LIGHT DEPENDENT REACTION INCLUDE?Non-cyclic photophosphorylation
    Cyclic photophosphorylation
  33. 33WHAT DOES NON-CYCLIC PHOTOPHOSPHORYLATION PRODUCE?ATP
    Reduced NADP
    Oxygen
  34. 34WHAT LINKS THE PHOTOSYSTEMS IN THE THYLAKOID MEMBRANES?Electron carriers
  35. 35WHAT ARE ELECTRON CARRIERS?Proteins that transfer electrons
  36. 36WHAT DO THE PHOTOSYSTEMS AND ELECTRON CARRIERS FORM?An electron transport chain
  37. 37WHAT IS AN ELECTRON TRANSPORT CHAIN?A chain of proteins through which excited electrons flow
  38. 38NON-CYCLIC PHOTOPHOSPHORYLATION: LIGHT ENERGY EXCITES ELECTRONS IN CHLOROPHYLLLight energy is absorbed by PSII
    The light energy excites electrons in chlorophyll
    The electrons move to a higher energy level
    These high energy electrons are released from the chlorophyll and move down the electron transport chain to PSI
  39. 39NON-CYCLIC PHOTOPHOSPHORYLATION: PHOTOLYSIS OF WATER PRODUCES PROTONS, ELECTRONS AND OXYGENAs the excited electrons from chlorophyll leave PSII to move down the electron transport chain, they must be replaced
    Light energy splits water into protons, electrons and oxygen - this is photolysis
    H2O --> 2H+ + 1/2 O2
  40. 40NON-CYCLIC PHOTOPHOSPHORYLATION: ENERGY FROM THE EXCITED ELECTRONS MAKES ATPThe excited electrons lost energy as they move down the electron transport chain
    This energy is used to transport protons into the thylakoid so that the thylakoid has a higher concentration of protons than the stroma, forming a proton gradient across the thylakoid membrane
    Protons move down their concentration gradient, into the stroma, via the enzyme ATP synthase, which is embedded in the thylakoid membrane
    The energy from this movement combines ADP and inorganic phosphate to form ATP
  41. 41NON-CYCLIC PHOTOPHOSPHORYLATION: ENERGY FROM THE EXCITED ELECTRONS GENERATES REDUCED NADPLight energy is absorbed by PSI, which excites the electrons again to an even higher level
    The electrons are transferred to NADP, along with a proton from the stroma, to form reduced NADP
  42. 42WHAT IS THE CHEMIOSMOTIC THEORY?Chemiosmosis is the process of electrons flowing down the electron transport chain and creating a proton gradient across the membrane to drive ATP synthesis.
    It's described by the chemiosmotic theory
  43. 43WHAT DOES CYCLIC PHOTOPHOSPHORYLATION PRODUCE?ATP
  44. 44WHICH PHOTOSYSTEM DOES CYCLIC PHOTOPHOSPHORYLATION USE?PSI
  45. 45WHY IS CYCLIC PHOTOPHOSPHORYLATION CALLED 'CYCLIC'?The electrons from the chlorophyll molecule aren't passed onto NADP, but are passed back to PSI via electron carriers
    This means the electrons are recycled and can repeatedly flow through PSI
    This process doesn't produce any reduced NADP or oxygen - it only produces small amounts of ATP
  46. 46WHERE DOES THE LIGHT INDEPENDENT REACTION TAKE PLACE?The stroma of the chloroplasts
  47. 47WHAT DOES THE LIGHT INDEPENDENT REACTION PRODUCE?Triose phosphate from carbon dioxide
    Ribulose bisphosphate
  48. 48WHAT CAN TROSE PHOSPHATE BE USED TO MAKE?Glucose and other useful organic substances
  49. 49WHAT DOES THE LIGHT INDEPENDENT REACTION NEED TO KEEP IT GOING?ATP
    H+ ions
  50. 50WHAT IS REGENERATED IN THE LIGHT INDEPENDENT REACTION?The reactions are linked in a cycle which means the starting compound, ribulose bisphosphate, is regenerated
  51. 51THE LIGHT INDEPENDENT REACTION: FORMATION OF GLYCERATE 3-PHOSPHATECO2 enters the leaf through the stomata and diffuses into the stroma of the chloroplast
    It's combined with ribulose bisphosphate (RuBP)
    Reaction is catalysed by the enzyme rubisco
    This gives an unstable 6 carbon compound, which quickly breaks down into 2 molecules of a 3 carbon compound called glycerate 3-phosphate
  52. 52THE LIGHT INDEPENDENT REACTION: FORMATION OF TRIOSE PHOSPHATEThe hydrolysis of ATP (from the light dependent reaction) provides energy to reduce the 3 carbon compound, GP, to a different 3 carbon compound, triose phosphate (TP)
    This reaction also requires H+ ions, which come from reduced NADP (from the light dependent reaction)
  53. 53THE LIGHT INDEPENDENT REACTION: FORMATION OF TRIOSE PHOSPHATE (2)Reduced NADP is recycled to NADP
    Some triose phosphate is then converted into useful organic compounds and some continues in the Calvin cycle to regenerate RuBP
  54. 54THE LIGHT INDEPENDENT REACTION: REGENERATION OF RIBULOSE BISPHOSPHATEFive out of every six molecules of TP produced in the cycle aren't used to make useful organic compounds, but to regenerate RuBP
    Regenerating RuBP uses the rest of the ATP produced by the light dependent reaction
  55. 55WHAT ARE HEXOSE SUGARS?Simple 6 carbon sugars
    e.g. glucose
  56. 56HOW IS ONE HEXOSE SUGAR MADE?By joining two molecules of triose phosphate (TP) together
  57. 57WHAT CAN HEXOSE SUGARS BE USED TO MAKE?Larger carbohydrates
  58. 58HOW MANY TIMES DOES THE CALVIN CYCLE NEED TO TURN TO MAKE ONE HEXOSE SUGAR?6
    Three turns of the cycle produces six molecules of triose phosphate (two molecules of TP are made for every carbon dioxide molecule used)
  59. 59HOW MANY MOLECULES OF TP ARE USED TO REGENERATE RIBULOSE BISPHOSPHATE?Five out of six
  60. 60FOR THREE TURNS OF THE CALVIN CYCLE, HOW MANY TP ARE USED TO MAKE A HEXOSE SUGAR?1
  61. 61HOW MANY TP MOLECULES ARE NEEDED TO FORM ONE HEXOSE SUGAR?2 TP molecules as a hexose sugar has 6 carbons
  62. 62HOW MANY TIMES MUST THE CYCLE TURN TO PRODUCE 2 MOLECULES OF TP TO MAKE 1 HEXOSE SUGAR?6 times
  63. 63HOW MANY ATP AND REDUCED NADP FROM THE LIGHT DEPENDENT REACTION DOES 6 TURNS OF THE CYCLE NEED?18 ATP
    12 reduced NADP
    This keeps the cycle going and makes sure there's always enough RuBP ready to combine with oxygen taken in from the atmosphere
  64. 64WHAT PRODUCTS OF THE CALVIN CYCLE ARE USED TO MAKE CARBOHYDRATES, LIPIDS & AMINO ACIDS?Triose phosphate (TP)
    Glycerate 3-phosphate (GP)
  65. 65CARBOHYDRATESHexose sugars are made from 2 TP molecules
    Larger carbohydrates (e.g. sucrose, starch, cellulose) are made by joining hexose sugars together in different ways
  66. 66LIPIDSMade using glycerol, which is synthesised from TP and fatty acids, which are synthesised from GP
  67. 67AMINO ACIDSSome are made from GP
  68. 68OPTIMUM CONDITIONS FOR PHOTOSYNTHESIS: HIGH LIGHT INTENSITY OF A CERTAIN WAVELENGTHLight is needed to provide the energy for the light dependent reaction
    The higher the intensity of the light, the more energy it provides
    Only certain wavelengths of light are used for photosynthesis
  69. 69WHAT PHOTOSYNTHETIC PIGMENTS ONLY ABSORB THE RED AND BLUE LIGHT IN SUNLIGHT?Chlorophyll a
    Chlorophyll b
    Carotene
  70. 70OPTIMUM CONDITIONS FOR PHOTOSYNTHESIS: TEMPERATURE AROUND 25°CPhotosynthesis involves enzymes (ATP synthase, rubisco etc)
    Below 10°C - enzymes become inactive
    Higher than 45°C - enzymes may start to denature
    At high temperatures, stomata close to avoid losing too much water, causing photosynthesis to slow down because less carbon dioxide enters the leaf when the stomata are closed
  71. 71OPTIMUM CONDITIONS FOR PHOTOSYNTHESIS: CARBON DIOXIDE AT 0.4%Carbon dioxide makes up 0.04% of the gases in the atmosphere
    Increasing this to 0.4% gives a higher rate of photosynthesis, but any higher and the stomata start to close
  72. 72OPTIMUM CONDITIONS FOR PHOTOSYNTHESIS: WATERPlants need a constant supply of water
    Too little - photosynthesis stops
    Too much - soil becomes waterlogged (reducing the uptake of minerals such as magnesium, which is needed to make chlorophyll a)
  73. 73LIMITING FACTORS OF PHOTOSYNTHESISLight, temperature, carbon dioxide
    If any of these factors is not at the right level, they can limit photosynthesis even if the other two factors are at the optimum level
  74. 74INCREASING PLANT GROWTHAgricultural growers know the factors that limit photosynthesis so try to create an environment where plants get the right amount of everything they need, which increases growth and so increases yield
  75. 75MANAGEMENT IN GLASSHOUSES: CARBON DIOXIDE CONCENTRATIONCarbon dioxide is added to the air
    e.g. by burning a small amount of propane in a carbon dioxide generator
  76. 76MANAGEMENT IN GLASSHOUSES: LIGHTLight can get in through the glass
    Lamps provide light at night time
  77. 77MANAGEMENT IN GLASSHOUSES: TEMPERATUREGlasshouses trap heat from sunlight, which warms the air
    Heaters and cooling systems can also be used to keep a constant optimum temperature, and air circulation systems make sure the temperature is even throughout the glasshouse
  78. 78RP 7: WHAT IS CHROMATOGRAPHY?Used to separate stuff in a mixture so you can identify the components
  79. 79RP 7: WHAT ARE 2 TYPES OF CHROMATOGRAPHY?Paper chromatography
    Thin-layer chromatography
  80. 80RP 7: HOW DOES CHROMATOGRAPHY WORK?A mobile phase - the molecules can move. In both paper and thin-layer chromatography, the mobile phase is a liquid solvent
    A stationary phase - where the molecules can't move. In paper chromatography, the stationary phase is a piece of chromatography paper. In thin-layer chromatography, the stationary phase is a thin layer of solid on TLC plate
  81. 81RP 7: WHAT ARE THE BASIC PRINCIPLES OF CHROMATOGRAPHY?The mobile phase moves through or over the stationary phase
    The components in the mixture spend different amounts of time in the mobile phase and the stationary phase
    The components that spend longer in the mobile phase travel faster or further. The time spent in the different phases is what separates out the components of the mixture
  82. 82RP 7: WHY IS IT GOOD THAT PLANTS CONTAIN SEVERAL DIFFERENT PHOTOSYNTHETIC PIGMENTS?Each pigment absorbs a different wavelength of light, so having more than one type of pigment increases the range of wavelengths of light that a plant can absorb
  83. 83RP 7: WHAT IS AN Rf VALUE?The distance a substance has moves through the stationary phase in relation to the solvent
    Each pigment has a specific Rf value, under specific conditions, which can be looked up in a database
  84. 84HOW TO CALCULATE Rf VALUESDistance travelled by spot
    ___________________________________
    Distance travelled by solvent
  85. 85RP 8: WHAT HAPPENS IN PSI DURING THE LIGHT INDEPENDENT STAGE?NADP acts as an electron acceptor and is reduced.
    This reaction is catalysed by a dehydrogenase enzyme
  86. 86RP 8: HOW COULD THE ACTIVITY OF A DEHYDROGENASE ENZYME BE INVESTIGATED?By adding a redox indicator dye to extracts of chloroplasts
    The dye acts as an electron acceptor and gets reduced by the dehydrogenase in the chloroplasts, giving a colour change
    e.g. the dye DCPIP changes from blue to colourless when reduced
  87. 87RP 8: HOW CAN YOU MEASURE THE RATE OF THE DEHYDROGENASE ACTIVITY?By measuring the rate at which DCPIP loses its blue colour using a colorimeter
    A colorimeter measures how much light a solution absorbs when a light source is shone directly through it
    A coloured solution absorbs more light than a colourless solution

Information

Description
A-Level Biology (UNIT 5) Flashcards on 5A: Photosynthesis, created by Beth Tonks on 02/01/2017.
Created by
Beth Tonks
Views
0
Rating

Feedback

What is it about?

What do you think of the new look?

How do you like it?