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Flashcards

5.2.1 Photosynthesis

Zoe Mitchell Biology A level English 88 cards

Draw a diagram to explain compensation points.

Cards in this deck (88)

  1. 1autotrophic nutritiontype of nutrition where organic molecules are synthesised from inorganic molecules such as carbon dioxide and water
  2. 2Photoautotrophsorganism that use light energy as a source of energy for photosynthesis.
  3. 3Photoautotrophs are also known as _____. Explain.Producers of a food chain - they provide energy and organic molecules to other, non-photosynthetic organisms.
  4. 4Compensation pointpoint where a plant is carrying out photosynthesis and respiration at the same rate so that there is no net gain or loss of glucose. Plants respire all the the time, but they only photosynthesis during daylight.
  5. 5Photona particle of light, each photon contains an amount (a quantum) of enegry
  6. 6Photosynthesis is an example of carbon ____. Explaincarbon fixation
    carbon dioxide is converted into sugars
  7. 7Draw a diagram to explain compensation points.Draw a diagram to explain compensation points.
  8. 8Equation of photosynthesis and respirationEquation of photosynthesis and respiration
  9. 9chloroplaststhe plant organelle in which photosynthesis is carried out
  10. 10chloroplast envelopedouble membrane that surrounds the chloroplast
  11. 11thylakoidflattened membrane-bound sacs found inside chloroplasts which contain photosystems and are the site of light-dependent stage of photosynthesis
  12. 12granuminner part of chloroplasts made of stacks of thylakoid membrane, where the light-dependent stage of photosynthesis takes place. Large surface area for lots of photosystems to trap light energy and lots of electron carriers and ATP synthase enzymes
  13. 13lamallaesections of thylakoid membrane which link the grana together
  14. 14Photosynthetic pigmentscoloured pigments, found in the thylakoid membranes, which absorb specific wavelengths of light and trap the energy needed for photosynthesis.
  15. 15Name 4 photosynthetic pigmentschlorophyll a, chlorophyll b, carotene and xanthophyll
  16. 16Photosystemsystem of photosynthetic pigments found in the thylakoid membranes, each containing accessory pigments which make up a light harvesting system, trapping photons and passing the energy to a primary pigment reaction centre (a molecule of chlorophyll a) whose electrons are excited during the light-dependent stage.
  17. 17How many photosystems are there? Which are?There are two photosystems – photosystem I which absorbs light at wavelength 700nm and photosystem II which absorbs light at 680 nm.
  18. 18Stromafluid-filled matrix of a chloroplast containing light-independent stage enzymes, starch grains and circular DNA. Location where the light-independent stage of photosynthesis occurs.
  19. 19Where does the light-dependent stage of photosynthesis occur?thylakoid membranes
  20. 20Where does the light-independent stage of photosynthesis occur?stroma of the chloroplasts
  21. 21Draw a diagram of a chloroplast.Draw a diagram of a chloroplast.
  22. 22A photosystem is a ____ _____ system which is ___ shaped and contains photosynthetic pigments. Light energy is absorbed by ____ pigments and funneled down to the ___ ____centre, consisting of a type of ____, at the base of the ____.light harvesting
    funnel
    accessory
    primary reaction
    chlorophyll a
    funnel
  23. 23Name 3 accessory pigments.Chlorophyll b
    Carotenoids
    Xanthophylls
  24. 24What type of pigment is a primary pigment?chlorophyll a
  25. 25What colour light does chlorophyll a absorb?red
  26. 26How many types of chlorophyll a are there? Which are?2
    P680
    P700
  27. 27What type of chlorophyll a is found in photosystem I? What wavelength of light does it absorb?P700
    700nm
  28. 28What type of chlorophyll a is found in photosystem II? What wavelength of light does it absorb?P680
    680nm
  29. 29What method can be used to investiagte which photosynthetic pigments are present in leaves?thin layer chromotography (TLC)
  30. 30Explain how to separate photosynthetic pigments using TLCGrind up several leaves with anhydrous sodium sulfate and some propanone Transfer the liquid to a test tube and add some petroleum ether and shake. Forms 2 distinct layers, the top layer includes the pigments. Transfer some of the top layer to another test tube with anhydrous sodium sulfate. Draw a pencil line near the bottom of the chromotography plate. Build up a single concentrated spot of the liquid onto the line. Once the spot is dry, put plate into a glass beaker with some solvent (mix propanone, cyclohexane and petroleum ether) just below the line. Put a lid on the beaker and leave until the solvent has almost reached the top of the plate. Take out of the beaker and mark the solvent front with a pencil. The different pigments will move up the plate at different rates, so they separate.
    For each coloured spot calculate the Rf value. Each coloured spot is a different pigment.
  31. 31How do you calculate Rf values?Rf = distance move by spot / distance moved by solent front
  32. 32Name the 4 stages of the light-dependent stage of photosynthesis.Light-harvesting at the photosystem
    Photolysis of water
    Photophosphorylation produces ATP
    Reduced NADP is made in non-cyclic photophosphorylation
  33. 33Photophosphorylationadding phosphate to a molecule using light
  34. 34Photolysisthe splitting of a molecule using light
  35. 35Electron carriersmolecules that can accept one or more electrons and then donate those electron to another carrier.
  36. 36Example of a electron carrierProteins embedded in the thylakoid membranes which contain an iron molecule at the centre are electron carriers and form the electron transport chain.
  37. 37NADPnicotinamide adenine dinucleotide phosphate - a coenzyme and a electron & hydrogen carrier
  38. 38Photolysis of waterIn the presence of light, an enzyme splits water molecules in protons, electrons and oxygen
  39. 39draw a diagram to show the equation of photolysis of waterdraw a diagram to show the equation of photolysis of water
  40. 40Photophosphorylation generate ___ from ____ and ____.ATP
    ADP & Pi
  41. 41Two types of photophosphorylationnon-cyclic
    cyclic
  42. 42Non-cyclic photophosphorylation Involves which photosystem? Produces?PSI and PSII
    ATP, oxygen and reduced NADP
  43. 43Cyclic photophosphorylation Involves which photosystem? Produces?PSI
    small quantities of ATP
  44. 44Compare non-cyclic and cyclic photophosphorylationCompare non-cyclic and cyclic photophosphorylation
  45. 45Explain non cyclic photophosphorylationPhoton of light strikes PSII and excites a pair of electrons in primary pigment reaction centre, which leave the chlorophyll molecule. The electrons move to a higher energy level.
    The electrons are passed along a chain of electron carriers (proteins with an iron molecule at the centre, embedded in the thylakoid membrane) to PSI.
    The electrons leaving PSII are replaced by electrons from the photolysis of water.
    As the electrons move along the electron transport chain they lose energy. This energy is use to pump protons across the thylakoid membrane into the thylakoid space via proton pumps, forming a proton gradient across the membrane.
    Protons move down their concentration gradients into the stroma via an enzyme called ATP synthase which combines ADP and inorganic phosphate to form ATP by chemiosmosis.
    The electrons are captured by another molecule of chlorophyll a in PSI and are excited by light energy once again.
    The electrons are transferred to NADP, along with a proton from the stroma, to form reduced NADP.
  46. 46First step of non-cyclic photophosphorylationPhoton of light strikes PSII and excites a pair of electrons in primary pigment reaction centre
  47. 47When a photon of light strikes PSII, what happens is non-cyclic photophosphorylation?excites a pair of electrons in primary pigment reaction centre, which leave the chlorophyll molecule. The electrons move to a higher energy level.
  48. 48In non-cyclic photophosphorylation, a pair of electrons are excited when light strikes PSII. They move to a higher energy level. What happens next?The electrons are passed along a chain of electron carriers to PSI.
  49. 49In non-cyclic photophosphorylation, what happens to PSII once the electrons have left to move to a higher energy level?The electrons leaving PSII are replaced by electrons from the photolysis of water.
  50. 50In non-cyclic photophosphorylation, the electrons lose energy as they move down the electron transport chain. What happens to this energy?This energy is use to pump protons across the thylakoid membrane into the thylakoid space via proton pumps, forming a proton gradient across the membrane.
  51. 51In non-cyclic photophosphorylation, a proton gradient is formed across the thylakoid membrane. What happens next?Protons move down their concentration gradients into the stroma via an enzyme called ATP synthase which combines ADP and inorganic phosphate to form ATP by chemiosmosis.
  52. 52In non-cyclic photophosphorylation, what happens to the electrons once they have moved down the electron transport chain?The electrons are captured by another molecule of chlorophyll a in PSI and are excited by light energy once again.
  53. 53In non-cyclic photophosphorylation,, after the electrons have been excited at PSI, what happens?The electrons are transferred to NADP, along with a proton from the stroma, to form reduced NADP.
  54. 54Draw a diagram to show how non-cyclic photophosphorylation works.Draw a diagram to show how non-cyclic photophosphorylation works.
  55. 55Explain cyclic phosphorylation.Light strikes PSI. A pair of electrons from the chlorophyll molecule become excited and leave the chlorophyll. They pass to an electron carrier system and are passed back to PSI. Small amounts of ATP are produced.
  56. 56What is the calvin cycle?metabolic pathway of the light-independent stage of photosynthesis, occurring in the stroma of the chloroplasts. Carbon dioxide is fixed with the products of the light-dependent stage to make organic compounds.
  57. 57For every turn of the calvin cycle, ___ carbon dioxide molecules is used and ___ molecules of TP are produced.1
    2
  58. 58Explain the calvin cycleCarbon dioxide diffuses into the leaf through the stomata, ending up in the stroma. of the chloroplasts.
    Ribulose bisphosphate (RuBP) – a five-carbon compound – combines with the carbon dioxide, catalysed by ribulose bisphosphate carboxylase (RuBisCO.).
    A very unstable 6-carbon compound is made which immediately breaks down into two molecules of a 3-carbon compound called glycerate-3-phosphate (GP.)
    GP is reduced, using H+ ions from reduced NADP, to make triose phosphate (another 3 carbon compound.) ATP, from the light-dependent stage, provides the energy for this reaction. 5 out of 6 molecules of TP are recycled by phosphorylated, using ATP, to make three molecules of RuBP.
  59. 59First stage of the calvin cycleCarbon dioxide diffuses into the leaf through the stomata, ending up in the stroma. of the chloroplasts.
  60. 60Once carbon dioxide has diffused into the stroma of the chloroplasts, what happens next in the calvin cycle?Ribulose bisphosphate (RuBP) combines with the carbon dioxide, catalysed by ribulose bisphosphate carboxylase (RuBisCO.).
  61. 61What is RuBP?Ribulose bisphosphate (RuBP) – a five-carbon compound
  62. 62In the calvin cycle, RuBP combines with carbon dioxide to form ?, catalysed by ?A very unstable 6-carbon compound
    ribulose bisphosphate carboxylase (RuBisCO.).
  63. 63Once RuBP combines with CO2 to form a very unstable 6 carbon compound, what happens next in the calvin cycle?immediately breaks down into two molecules of a 3-carbon compound called glycerate-3-phosphate (GP.)
  64. 64GP Name How many carbons?glycerate-3-phosphate
    3-carbon compound
  65. 65In the calvin cycle, what happens after GP has formed?GP is reduced, using H+ ions from reduced NADP, to make triose phosphate (another 3 carbon compound.) ATP, from the light-dependent stage, provides the energy for this reaction.
  66. 66TP Name How many carbons?triose phosphate
    3-carbon compound
  67. 67When TP is formed, what happens next in the calvin cycle?5 out of 6 molecules of TP are recycled by being phosphorylated, using ATP, to make three molecules of RuBP.
  68. 68Draw a diagram to explain the calvin cycle.Draw a diagram to explain the calvin cycle.
  69. 69Explain why the calvin cycle only runs during the day.it needs to use the products (ATP and reduced NADP) of the light-dependent stage of photosynthesis
  70. 70Explain what happens to the levels of RuBP, TP and GP during nighttime.During the night, the calvin cycle can't run so GP can’t be converted to TP and RuBP, so levels of GP will be high as it accumulates, and levels of TP and RuBP will be low because there isn’t any ADP or reduced NADP to turn GP to TP and then to RuBP.
  71. 71Does the calvin cycle run all the time?No, only when it is light.
  72. 72Draw a diagram to show the levels of RuBP, TP and GP during bright light and dim light.Draw a diagram to show the levels of RuBP, TP and GP during bright light and dim light.
  73. 73Uses for TPMakes Carbohydrates
    TP is also a starting material for amino acids, fatty acids and glycerol
    The rest of the TP made in the Calvin cycle is recycled to regenerate the supply of RuBP.
  74. 74How many molecules of what are required to regenerate RuBP in the calvin cycle?5 molecules of TP make 3 molecules of RuBP
  75. 75Explain how TP is used to make carbohydrates.two TP molecules are joined to make hexose sugars (i.e. glucose) and the hexose sugars can then be joined together to make larger carbohydrates (i.e. starch, sucrose and cellulose)
  76. 76Limiting factorsAt any given moment, the rate of reaction is limited by the factor that is present at its least favourable level.
  77. 77Explain how light intensity can be a limiting factor for photosynthesis.provides the energy for the first stage of photosynthesis which produces ATP and reduced NADP. Also, cause stomata to open so gaseous exchange can happen and the transpiration stream can occur.
  78. 78Explain how carbon dioxide can be a limiting factor for photosynthesis.if too low (under 0.01%), RuBP cannot accept carbon dioxide so it accumulates, GP can’t be made and therefore TP can’t be made.
  79. 79Draw a diagram to show the effect of carbon dioxide concentration on the levels of TP, GP and RuBP.Draw a diagram to show the effect of carbon dioxide concentration on the levels of TP, GP and RuBP.
  80. 80Why is photosynthesis sensitive to temperature?Calvin cycle involves many enzyme-catalysed reactions so is sensitive to temperature.
  81. 81Explain what happens to the rate of photosynthesis from low temperature to about 30 degrees.rate of photosynthesis increases and temperature increases (as long as there are no other limiting factors.)
  82. 82Explain what happens to the rate of photosynthesis from about 30 degrees to 45 degrees.stomata close to avoid losing too much water so not enough carbon dioxide can enter leaf, Oxygen competes with carbon dioxide for RuBisCO’s active site and photorespiration is favoured. This reduces the quantity of GP (and so also TP) produced and so RuBP can't be regenerated.
  83. 83What does photorespiration do to the quantity of GP, TP and RuBP?Oxygen competes with carbon dioxide for RuBisCO’s active site and photorespiration is favoured. This reduces the quantity of GP (and so also TP) produced and so RuBP can't be regenerated.
  84. 84Explain what happens to the rate of photosynthesis from above 45 degrees.At temperatures above 45 degrees, enzymes are denatured. Concentrations of GP and TP are reduced and so RuBP can't be regenerated.
  85. 85Draw a graph to show temperature and rate of photosynthesis.Draw a graph to show temperature and rate of photosynthesis.
  86. 86Water stressthe condition a plant will experience when water supply becomes limiting
  87. 87What effects does water stress have on a plant?Roots are unable to take up enough water to replace the water lost via transpiration. Cells becomes plasmolysed Roots produce abscisic acid which is translocated to the leaves and causes the stomata to close. Gas exchange is reduced. Tissues become flaccid and wilt. Rate of photosynthesis is reduced.
  88. 88Explain how to investigate limiting factors of photosynthesis.Put some pondweed in a test tube and fill it with water and connect it to a capillary tube filled with water. Connect a gas syringe to the end of the capillary tube and make sure that the system has no air bubbles. Leave the plant to photosynthesis for a set time. At the end of the experiment, use the gas syringe to draw the air bubble alongside a ruler and measure the length of the gas bubble
    Repeat and change 1 factor, such as light intensity, and compare the rate of oxygen production.

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A level Biology (Module 5: Communication, homeostasis and energy) Flashcards on 5.2.1 Photosynthesis, created by Zoe Mitchell on 20/02/2017.
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