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communication, homeostasis and energy > photosynthesis > Flashcards

photosynthesis Flashcards

1
Q

what is chemiosmosis and which molecule does it involve the generation of?

A

movement of hydrogen ions down their electrochemical gradient and helps generate ATP

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2
Q

what moves through ATP synthase?

A

hydrogen ions/protons

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3
Q

how does the electron transport chain work?

A
  • electrons gain energy by absorbing photons
  • they pass from carrier to carrier which each have a lower energy level
  • energy is released as electrons move down the chain
  • the energy is used to pump protons across a membrane against their concentration gradient
  • this creates an electrochemical gradient, maintained by an impermeability to hydrogen ions
  • protons move down channel proteins linked to ATP synthase to resynthesise ATP
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4
Q

how do electrons become excited?

A
  • absorb light energy and pass into an electron transport chain
  • released when chemical bonds are broken
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5
Q

what is a photosynthetic pigment?

A
  • pigments that can absorb certain wavelengths of light
  • used in the light dependent reaction
  • found in the thylakoids
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6
Q

outline the importance of photosynthetic pigments in photosynthesis

A
  • accessory pigments absorb light (photons)
  • they pass the energy to the reaction centre where the electrons are
  • primary pigment becomes oxidised as the excited electrons move to the electron acceptor and down the ETC
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7
Q

is photosynthesis endothermic or exothermic?

A

endothermic

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8
Q

is respiration endothermic or exothermic?

A

exothermic

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9
Q

what is meant by the compensation point?

A

rate of photosynthesis = rate of respiration

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10
Q

what is the structure to function of a chloroplast?

A

stroma - chemical reactions, enzymes etc
granum - SA:V ratio
thylakoid - ATP synthase, ETC

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11
Q

what is a photosystem?

A
  • light harvesting system
  • made of photosynthetic pigments (primary and accessory)
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12
Q

what is the importance of accessory pigments?

A

absorb different wavelengths of light for max light absorption

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13
Q

what do electron acceptors do?

A

pass electrons from the photosystem to the ETC

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14
Q

what are examples of hydrogen carriers?

A
  • NADP
  • FAD
  • NAD
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15
Q

where does the light dependent stage occur?

A

on the thylakoid membrane

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16
Q

what is the function of the light dependent phase?

A

transduce light energy into electrical energy

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17
Q

what are three key stages of the light dependent phase?

A
  • excitation of photosystems by light energy
  • production of ATP via the ETC
  • reduction of NADP and photolysis of water
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18
Q

what are the products of photolysis?

A
  • oxygen molecule
  • electrons
  • protons
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19
Q

what is the importance of photolysis?

A
  • electrons replace the ones lost in photosystem II (PSII)
  • protons reduce NADP
  • oxygen is a byproduct
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20
Q

what is photophosphorylation?

A

use of light energy to make ATP

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21
Q

what are the two types of photophosphorylation?

A

cyclic and non cyclic

22
Q

when does cyclic occur?

A

limited water availability

23
Q

which photosystems does each type of photophosphorylation involve?

A

cyclic - PS1
non cyclic - PS2 and PS1

24
Q

what are the differences in production in the two types of photophosphorylation?

A
  • ATP is produced in both
  • reduced NADP is only produced in non cyclic
25
Q

what are the two stages of photsynthesis?

A
  • light dependent
  • calvin cycle/light independent
26
Q

what are the three main steps of the calvin cycle?

A
  • carbon fixation
  • reduction of GP to TP
  • regeneration of RuBP
27
Q

what happens in carbon fixation?

A
  • rubisco catalyses the attachment of CO2 to 5C RuBP
  • this results in an unstable compound
  • it breaks down into 2 lots of 3C compounds called GP
  • this happens for 3xCO2 so 6GP produced
28
Q

what happens in GP reduction?

A
  • GP converts to TP with NADPH and ATP
  • oxidation of NADPH transfers a hydrogen atom to GP and ATP provides energy
  • 6TP produced
29
Q

what happens in the regeneration of RuBP?

A
  • one of 6 TP molecules forms half a glucose (two calvin cycles for one glucose molecule)
  • remaining 5 recombine to form 3 RuBP (5x3C=3x5C)
  • requires ATP
30
Q

why does light intensity affect rate?

A
  • excites electrons in photosystems
  • photolysis of water
31
Q

why is light necessary?

A
  • used to produce ATP for the calvin cycle
  • produce protons to reduce NADP
32
Q

what happens if light is limited?

A
  • GP increases as NADPH and ATP aren’t synthesised
  • TP and RuBP reduce
33
Q

why does CO2 affect rate?

A
  • source of carbon for carbon fixation in the calvin cycle
34
Q

why is carbon dioxide necessary?

A

combines with RuBP and enzyme rubisco to generate GP and TP

35
Q

what happens if carbon dioxide is limited?

A
  • reduction in GP and TP production and increase in RuBP as it isn’t being used
36
Q

why does temperature affect rate?

A

controls enzyme based reaction

37
Q

why is heat necessary?

A
  • rubisco is used for carbon fixation
  • ATP synthase is used to produce ATP
38
Q

what happens if temperature is limited?

A

all three products decrease as the calvin cycle can’t occur

39
Q

why is the dark stage an inaccurate and accurate way to describe the light independent stage?

A

accurate as no photons are required but inaccurate as it requires products from the light dependent stage

40
Q

what is the name of the primary pigment?

A

chlorophyll A

41
Q

name some accessory pigments

A

chlorophyll b, carotenoids, carotene, xanophylls

42
Q

what is the precise location of photosynthetic pigments?

A

photosystems in the thylakoid membrane

43
Q

outline the processes involved in the production of ATP via chemiosmosis

A
  • occurs in mitochondria
  • active transport of H+ ions from the cytyosol to the intermembrane space
  • creates a proton gradient and generates proton motive force
  • protons move down concentration gradient through ATP synthase
  • energy powers enzymes to catalyse the synthesis of ATP from ADP and Pi
44
Q

summarise the importance of coenzymes

A

CoA: transfers acetyl from link to krebs
ADP and ATP:
- phosphorylation of glucose to form hexose bisphosphate
- removes phosphate group from TP in glycolysis
NAD:
- oxidation of triose phosphate in glycolysis
- oxidises pyruvate in link reaction
- reduces pyruvate in lactate fermentation and ethanal in alcoholic fermentation

45
Q

what are the uses of TP within the plant?

A
  • regenerate RuBP
  • form a glucose molecule
46
Q

explain why temperature has a greater effect on the rate of the LDR

A
  • there are more enzyme-controlled reactions
  • if enzymes denature the calvin cycle can’t continue
47
Q

what is the role of chloroplasts in photosynthesis?

A
  • LIR and LDR take place in thylakoid membrane
  • 2 photosystems containing photosynthetic pigments to absorb light
  • ETC to move electrons and produce ATP
  • RuBP as a CO2 acceptor and GP is produced and converted to TP
48
Q

suggest two ways that the ultrastructure of a chloroplast is altered in high temps and explain the effect on photosynthesis

A
  • phospholipid bilayer becomes fluid and unstable so ETC and ATP synthase don’t function and LDR cannot continue
  • damage to chlorophyll reduces LDR
49
Q

what is Q10?

A

temperature coefficient - effect of raising the temp 10 degrees when measuring rate of reaction

50
Q

what is the rough Q10 of most biological systems?

A

2-3

51
Q

what is a limiting factor?

A

the factor that will determine the rate when at lower level

communication, homeostasis and energy (6 decks)

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