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Flashcards

Photosynthesis

Sparkle Shine Biology GCSE English 69 cards

Cards in this deck (69)

  1. 1What are the three groups that photosynthesise?-Plants
    -Cynobacteria
    -Algae
  2. 2Esentially, what is photosynthesis?-The conversion of simple inorganic molecules like water and CO2 in to larger organic molecules like glucose
  3. 3What is the definition of carbon fixating?-Converting carbon dioxide into sugar
  4. 4What is the relationship between photosynthesis and aerobic respiration?-They form a cycle.
    -The products of one reaction are the reactants of another
    -Between the two, they recycle the carbon dioxide and oxygen in the atmosphere
  5. 5What is the light compensation point?-Think of it like the equillibrium
    -This is when the volume of oxygen produced and carbon dioxide taken in by photosynthesis is the same as the volume of oxygen removed and carbon dioxide released in aerobic respiration
    -This means that there is not net movement of gases in or out of the plant
    (The other gives off exactly what they need so there is no need for extra input therefore no need for net movement in the plant)
  6. 6Name some of the features of chloroplasts-Thylakoids
    -Grana
    -Intergranal lamellae
    -Stroma
    -Inner and outer membrane
    -Oil droplets are back up for synthesis of new chloroplast envelopes
    -intermembrane compartment
  7. 7What are the two parts to photosynthesis?The light dependent and the light independent stages
  8. 8Give me the fact file of the light dependent stage-Location; Thylakoid membranes/ grana
    Reactants; water for photolysis with light energy
    Products; oxygen + NADPH +ATP
  9. 9What is the use of NADP?This is molecule that picks up the electron once it has been through the electron transport chain
    -It becomes reduced NADP/ NADPH
  10. 10Give me the fact file of the light- independent reaction-Location; stroma
    Reactants; CO2 + NADPH + ATP
    Products; Glucose
  11. 11What photosynthetic pigments can you name?Chlorophyll a X2
    Chlorophyll b
    Xanthophyll
    Carotenoid
  12. 12What is a photosystem?-They are found embed in the thylakoid membrane
    -They are conical shaped
    -Lined with accessory pigments that transport photons of light to the Primary Pigment Reaction Centre, which is found at the end of the cone , in the centre
    -This is where chlorophyll a is
  13. 13Talk to me about chlorophyll a-There are two types
    -Chlorophyll a (P700) ; this has a wavelength peak at around 700 and is only found in photosystem I
    -Chlorophyll a (P680); has a peak at 680 and is found at PSII
  14. 14What is the role and importance of water?-Helps keep structure in the plant, maintains turgidity
    -Source of oxygen
    -Source of H+ ions for phosphorylation
    -Good transport medium
    -Photolysed to replace electrons lost when photon struck PSII
  15. 15What is phosphorylation?-The process of converting ADP to ATP, through the addition of a Phosphate group
  16. 16Go on, I know you want to tell me about photophosphorylation-There are two types, cyclic and non cyclic
    -Cyclic involves only PSI and isnt as efficient in ATP production
    -Non cyclic phosphorylation includes both photosystems and produces oxygen, ATP and NADPH
  17. 17What is the definition of electron carriers?-Molecules that can accept one or more electrons before passing them on to another carrier
  18. 18Here we go, non cyclic phosphorylation. Outline it for me.1. Photon strikes PSII
    2. photon goes to PPRC where electron gets excieted
    3. Electron carrier pick up, using iron ion and transfers electron down ETC, redox reactions
    4. Proteins use electron energy for active transport of protons
    5.PSI re-excites electrons and passes then to NADP
    6. Thylakoid membrane has gradient and proton diffuse out through protein associated with ATP synthase
    7. proton helps ADP --> ATP
    8. Protons join electrons to reduce NADP
  19. 19Name one thing about the structure of an electron carrier-It contains an iron ion which reduces when the carrier picks up a electrons and oxidises when it loses them
  20. 20The light independent reaction: Location- ? Reactants-? Products-?-Stroma
    -NADPH + ATP + CO2
    -Glucose
  21. 21What is the main enzyme in the calvin cycle? What does it do?-Rubisco
    -It catalyses the joining of CO2 and RuBP
  22. 22What are the main steps of the Calvin cycle?-Carbon fixation, Reduction, Regeneration
    -CO2 joins with RuBP to form two GP molecules
    -These then rearrage to form 2 TP molecules
    -Some of this TP is used to make glucose, the other is to regenerate RuBP
  23. 23How are RubisCO molecules activated?-When there is extra ATP in the stroma
    -By the cofactor of a Mg ion
    -(RubisCO enzymes like the pH 8)
  24. 24How many turns of the Calvin cycle to produce one glucose molecule6!!!
  25. 25Why is it that the amount of RuBP in the stroma is quite low?-A lot of it isnt needed as now amounts are lost
    -This is because they keep getting regenerated
  26. 26How can lack of Nitrate ions in the soil affect the levels of RubisCO in plants?RubisCO is an enyme.
    -As enzymes are proteins, they are essentially made from amino acids
    -Amino acids contain nitrogen
    -Without the nitrogen, the amino acids cant be made and neither can RubisCO
    -So RuBP and CO2 cant be joined and cycle wouldnt start
  27. 27What factors affect photosynthesis?-Light
    -Temperature
    -CO2 availability
    -Water avalability
  28. 28How does light affect photosynthesis?-Light can cause the stomata to open
    -This means that more gases are exchanging, so photosynthesis can happen more. And the transpiration stream delivers more water
    -Light is also needed for photophosphorylation in the first stage
  29. 29How does the amount of light affect the Calvin cycle?-In little or no light, the amount of the substances vary
    -GP increases as it can not be reduced to TP (no NADPH from light dependent)
    -TP levels fall as GP can not be reduced
    -RuBP levels fall as no TP to regenerate
  30. 30How does the amount of CO2 affect the Calvin cycle?-No CO2 means it cant join with RuBP
    -RuBP increases
    -GP cant be made
    -So TP cant be made
  31. 31How does the temperature affect the Calvin cycle?-Each stage is enzyme controlled: so temperatures change enzyme activity and therefore cycle production
    -higher than 30 degrees may lead to photorespiration (oxygen competes for RubisCO)
    -Less CO2 joining so less GP (more RuBP) and less TP so less glucose eventually less RuBP
  32. 32How does the lack of water availability affect the Calvin cycle?-Roots cant replace water lost via transpiration
    -Cells become plasmolsyed
    -Roots cant help but produce abscsic acid, which when taken/ translocated to leaves cause stomata to close
    -This means less gaseous exchange
    -Rate of photosynthesis decreases
    -Tissues turn flaccid and leaves wilt
  33. 33Why is photosynthesis important?-This is how plants gain some of the nutrients that they need to survive
    -This is called autotrophic nutrition; Their "food" is produced from themselves
  34. 34What is the purpose of the light dependent stage?-To form enough NADPH to then go to the calvin cycle to reduce GP made from RubisCO and CO2
    -Also no ATP is synthesised to phosphorylate/ dephosphorylate molecules
  35. 35What is photorespiration?-In certain temperatures, O2 has a higher affinity to RubisCO so less CO2 binds
    -O2 is acting as a competitive inhibitor
    -This means that less GP is being made
    -Less is being reduced to TP
    -Less glucose can be made and RuBP starts to fall
  36. 36What is the fate of electrons from the non-cyclic photophosphorylation?-They get passed from the PSI to FERRODOXIN
    -This then passes the electron pair to NADP to reduce it
  37. 37What happens during cyclic photophosphorylation?-The electrons get passed down a series of electron carriers before returning to PSI
    -A small amount of ATP is produced
  38. 38Outline the role of water in photosynthesis-Water supplies a pair of electrons to replace those lost in photoexcitation
    -They also add to the H+ concentration in the thylakoid space
  39. 39How is ATP involved in the Calvin Cycle?-It supplies energy for the reduction of GP to TP
    -It also becomes dephosphorylated so that some of the TP can become phosphorylated
  40. 40What are the fates of TP?-Some is used to regenerate RuBP
    -Some is converted into glucose
    -Some converted into the other biological molecules you know
  41. 41What basically happens in each stage of photosynthesis?1) Light harvesting = light harvesting
    2) Light-dependent = Photolysis
    3) Light-independent = reduction of carbon dioxide
  42. 42What are the three raw materials that leaves were built to collect?-Water
    -CO2
    -Light
  43. 43How is the leaf adapted to collect maximum sunlight?-large surface area to collect as much light as possible
    -Mosaic leaf arrangement ( so minimal overlapping occurs)
    - The waxy cuticle is transparent which lets light through to the palisade cells
    -The palisade cells have well-developed cytoskeletons, which allow th movement of chloroplasts into the best positions
  44. 44What adaptations do the leave have to improve the process of gaseous exchange-Lots of stomata, so there are more places for gaseous exchange
    -Air spaces in the spongy mesophyll which can increase the rate of CO2 diffusion
  45. 45In what way is the plant adapted to achieve maximum amount of water?-It is connected to many well developed vascular xylem tissues
    -These bring water to the cell for photosynthesis
  46. 46Now the chloroplasts, how are they adapted to undergo their function? (3)-The stroma surrounds the grana so the products from there can easily be passed to the stroma
    -The granal/thylakoid membranes have a large surface area to fit in more pigments and proteins e.g ATP synthase
    -Chloroplast has its own DNA and ribosomes, so it able to quickly produce the proteins needed e.g. electron carriers
  47. 47What two random molecules are found in the stroma and why are they there?Starch grains and oil droplets
  48. 48What structure is similar to the photosynthetic pigment, chlorophyll's porphyrin ring?Haem group in haemoglobin
  49. 49What is the significance of the 1. Magnesium ion in porphyrin ring 2. Long hydrocarbon chain?1. This is where the electrons become excited. When the light hits, the electrons in magnesium move to a higher energy level, initiating photophosphorylation
    2. The long hydrocarbon chain provides a non-polar region. This means that the pigment is able to remain embedded in the hydrophobic thylakoid membrane
  50. 50What are the accessory pigments for?-They capture the light that chlorophyll a is unable to capture
    -They then pass the chemical energy down to chlorophyl a, where it is to be used in the first stage
  51. 51TOP TIP!Remember that in photosytems, the energy is what is transferred from one pigment to another, not the electrons!
  52. 52Where are the two photosystems most likely to be foundPSII would be on the thylakoid membrane
    PSI would be on the intergranal membrane
  53. 53Once the light has been captured, what are the two main uses for its energy?-To phosphorylate ADP to ATP via photophosphorylation
    -To split water into protons, electrons and oxygen
  54. 54Why is it that the electrons lose energy as they go along the ETC?It is not that the energy is being directl take to pump out hydrogen
    -It's that each next electron carrier has a lower energy level, so the electrons lose energy
    -That lost energy is then used to pump the protons, so it's kind of like a useful by process
  55. 55What is involved in cyclic photophosphorylation?So when the electrons in the PPRC are excited and passed onto the electron carriers, the electron carrier takes the electrons on a wild goose chase because they eventually end up at the same Photosystem
    -But enough energy is used to form some ATP for the next stage
  56. 56What is the significance of photolysis?-They photosystems become excited and lose electrons which rose to a higher energy level
    -This means that they are positively charged
    -Before they can become excited again, they need to replace the electrons lost.... ie photolysis
  57. 57Where can photolysis occur?This only happens in photosystem one, as it is the only one with the right enzymes
  58. 58What is the fate of the photolysis products?-The electrons replace those lost in the PSII, which travel down non cylic route, eventually ending up in reduced NADP
    -The protons undergo chemosmosis, before ending up in reduced NADP
    -The oxygen is either used in respiration or diffuses out of the cell, via the stomata
  59. 59If photolysis can't occur at PSI, then how does it replace its electrons?It uses PSII
    This is was ensures the continuous movement of electrons down the thylakoid membrane
    -Think of it as a factory process thingy
    -PSII is making own electrons but PSI is just taking the freshly made ones
  60. 60TOP TIP!It's nicer to think that the electron and protons meet first, before reducing NADP
  61. 61Compare and contrst cyclic and non cyclic photophophorylationSimilarities:
    -Both involve the transfer of electrons in a series of redox reactions
    -Both use photosystems where chlorophyll is the primary pigment
    -Both produce ATP
    Differences:
    -N.C uses both photosystems, C only uses PSI
    -N.C involves photolyis, C doesn't
    -N.C also produces NADP, C doesn't
    -Electrons are returned to C, not is N.C
  62. 62Outline the Calvin Cycle1) CO2 reacts wit RuBP (rubisco) forming hexose compound
    2) Compound breaks down into 2 x GP
    3) GP is reduced and phosphorylated to 2 x TP, using 1 x ATP and 1 X NADPH
    4) 5/6 TP is used to regenerate RuBP ( another ATP USED) and one to go to 6 carbon molecule
    5* this can be polymerised to form starch
  63. 63How do you get from Triose Phosphate to the four main biological molecules (If you can get this right then you. are. smart!)Carbohydrates; (like sucrose) TP makes hexose sugars; glucose and fructose
    Lipids; Fatty acids can be formed from GP and the glycerol comes from the triose phosphate!
    Proteins; amino acids can be made from GP with the help of acetyl CoA
    Starch; the hexose sugars can be polymerise into forming starch
  64. 64TOP TIP!Yes, all the factors may be operating together but just one at any given time is affecting the rate!
    The one that affects the rate is the factor that is at the least favourable condition
    -So look at the factors and see which one is furthest away from the optimum *
    Remember that....
  65. 65What are the two ways in measuring the rate of photosynthesis?-The rate of which oxygen is produced
    -The rate at which carbon dioxide is removed
  66. 66State two limitations to the way that we measure photosynthesis1) Not all of the oxygen produced is released as some is used in aerobic respiration as the final electron acceptor
    2) The plant actually uses more CO2 than taken in, because photosynthesis provides some, so less is taken in than used
  67. 67Between temps of 0 -25 degrees the rate of photosynthesis..........doubles for each 10 degree increment
  68. 68What are the two best wavelengths for photosynthesis to occur at?Blue and red
  69. 69—

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GCSE Biology Flashcards on Photosynthesis, created by Sparkle Shine on 13/09/2017.
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