Photosynthesis Flashcards

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1
Q

activities that need enegy

A
  • active transport (selective reabsorption of glucose + Aa in the kidney)
  • anabolic reactions (growth)
  • movement of cilia/flagella
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2
Q

chemiosmosis

A
  • diffusion of protons from high to low
  • movement of protons releases energy
  • used to attach P to ADP = ATP
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3
Q

how are electrons excited

A
  • absorbing light

- when chemical bonds are broken in respiratory substrate mol (glucose)

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4
Q

electron transport chain

A
  • series of electron carriers
  • each have lower energy levels
  • excited electron moves from one carrier to the next
  • releases energy
  • pumps protons across a membrane
  • proton gradient
  • PG maintained bc membrane is imperm to H+
  • H+ move through hydrophilic channel linked to enzyme ATP synthase
  • catalyses ATP formation
  • flow of protons provides energy to synthesis ATP
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5
Q

chloroplast structure

A
  • network of membranes = large SA
  • maximises absorption of light
  • membranes form flattened sacs = thylakoids
  • thylakoids stacked = grana
  • grana joined by lamellae
  • chlorophyll embedded in thylakoid membrane
  • fluid in chloroplast = stroma
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6
Q

chlorophyll

A
  • primary pigment = chlorophyll a
  • a is in the reaction centre
  • diff pigments absorb diff wavelengths of light
  • pigments in the photosystems
  • chlorophyll b (+other pigments) are embedded in the thylakoid membrane of the chloroplasts = light harvesting system
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7
Q

what stages occur in

  • light dependant
  • light independent
A

non-cyclic/cyclic phosphorylation :

  • energy from sun absorbed
  • forms ATP
  • reduced NADP

Calvin cycle

  • ATP supplies energy
  • H from reduced NADP + CO2 build glucose
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8
Q

non - cyclic phosphorylation

A
  • PSII = 680nm
  • PS1 = 700nm
  • PSII absorbed light
  • excites electron
  • released from reaction centre
  • passed through ETC to PSI
  • e- lost from PSII replaced by photolysis
  • excited e- lose energy
  • energy used to pump H+ into thylakoid via proton pumps
  • chemiosmosis
  • PG
  • H+ diffuse down PG into stroma
  • via enzyme ATP synthase
  • energy released combines ADP+Pi = ATP
  • PSI absorbs light
  • excites e-
  • e- leaving ETC from PSI accepted
  • along with H+
  • by coenzyme NADP
  • forms reduced NADP
  • reduced NADP provides hydrogen to form glucose
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9
Q

photolysis

A

H2O = 2H+ + 2E- + 1/2O2

- H2O split using energy from the sun

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10
Q

cyclic phosphorylation

A
  • e- leaving PSI are returned to PSI
  • reduced NADP isn’t formed
  • ATP still produced without e- from PSII
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11
Q

calvin cycle

A
  • CO2 into spongy mesophyll of leaves
  • through stomata
  • into stroma of chloroplasts
  • C in CO2 is fixed
  • combines with RuBP
  • RuBisCO catalyses reaction
  • unstable 6c intermediate formed
  • breaks down
  • 2x GP (3c)
  • GP converted to 2x TP (3c)
  • using H atom from reduced NADP + ATP from light dependant
  • 5c from 2xTP regenerates RuBP so cycle continues (used rest of ATP from light dependant)
  • 1c is converted into organic mol (glucose/lipids)
  • 6x of cycle to make 1 hexose sugar : 18ATP : 12 reduced NADP
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12
Q

photorespiration

A
  • oxygen is a competitive inhibitor of RuBisCO
  • produces phosphoglycolate
  • reduces GP production
  • when CO2 conc is low
  • phosphoglycolate = toxic 2c
  • converted into other organic mol using ATP
  • RuBisCO has a higher affinity for CO2 than O2
  • reduces efficiency of photosynthesis
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13
Q

factors affecting rate of photosynthesis

A
  • light intensity (ATP + RNADP produced at higher rate
  • CO2 conc - inc C fixation in CC + inc rate of TP production
  • temperature : affects enzyme controlled reactions (C fixation) : denature proteins/inc ROR : stomata close to avoid water loss stopping diffusion of CO2 reducing rate of light independent then stopping photosynthesis.
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14
Q

limiting factor

A
  • when one of the factors needed for a process is in short supply and reduces the rate of the process
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15
Q

effect of reducing light intensity on Calvin cycle

A
  • reduce ATP
  • reduce NADPH
  • conc of GP will inc
  • TP will dec
  • conc of RuBP dec
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16
Q

effect of CO2 + temp on calvin cycle

A

lower temp :

  • enzymes + substrate have less KE
  • fewer successful collisions
  • less ESC
  • reduced ROR
  • lower conc of GP, TP and RuBP
  • same as high temp (enzymes denatured)

CO2:

  • less GP
  • less TP
  • RuBP inc bc still formed from TP but not being fixed to CO2