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Biology > 5.2.1 Photosynthesis > Flashcards

5.2.1 Photosynthesis Flashcards

1
Q

photosystem

A

chlorophyll and other pigments arranged in complexes with proteins such as lipids and enzymes
- contains a reaction center

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2
Q

what does the reaction center of photosystem contain?

A

chlorophyll A

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3
Q

what does the primary photosynhetic pigment do?

A

abdsorbs light energy at particular wavelength for light dependant reaction

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4
Q

what does action spectrum show ?

A

rate of photosynthesis at different wavelengths of light

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5
Q

what is chemiosmosis ?

A

movement of H+ ions through ATP synthase producing a proton motive force to form ATP from ADP and Pi

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6
Q

what molecule is the final electron acceptor

A

NADP

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7
Q

what molecule is dehydrogenated in non cyclic photophosphorylation

A

water

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8
Q

where does photolysis of water occur

A

inside the thylakoid

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9
Q

where does atp synthase occur

A

in the stroma

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10
Q

what molecule is hydrogenated in non cyclic photophosphorylation

A

NADP

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11
Q

which wavelenth of light does the chlorophyll absorb in photosystem 2

A

680nm

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12
Q

which wavelenth of light does the chlorophyll absorb in photosystem 1

A

700nm

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13
Q

where do protons for chemiosmois come from

A

from the photolysis of water

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14
Q

why is it called phosphorylation

A

your in light adding a phosphate group to make ATP

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15
Q

what is phosphorylated

A

ADP

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16
Q

products of non-cyclic photophosphorylation

A

ATP
NADPH
O2

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17
Q

general name of pigment complexes in non-cyclic photophosphorolyation

A

photosystems

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18
Q

why is the pH of the thylakoid lumen lower than that of the stroma

A

the thylakoid contains a higher concentration of H+ ions than to the stroma so more acidic= lower pH

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19
Q

what is the function of the pH gradient in the non-cyclic photophosphorylation

A

forms electrochemical gradient so chemiosmosis occurs so H+ ions move down concentration gradient through the ATP synthase to produce the protein motive force to make ATP

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20
Q

explanation of cyclic photophosphorylation

A

light energy is absorbed by photosystem 1
chlorophyll a releases an electron
shifts to electron carrier and eventually back to PS1 to replace e-
helps keep electrochemical gradient
H+ then move down conc gradient through the ATP synthase to produce ATP by chemiosmosis from ADP and Pi

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21
Q

products of cyclic photophosphorylation

A

ATP

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22
Q

what is the purpose of cyclic phosphorylation

A

to produce more ATP so there’s enough for calvin cycle

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23
Q

how are electrons raised to higher energy levels or excited

A

electrons present in pigment molecules such as chlorophyll are excited by absorbing light from the sun
- high energy electrons are released when chemical bonds are broken in respiratory substrate molecules

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24
Q

what are excited electrons passed into

A

electron transport chain and used to generate a proton gradient

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25
what makes up an electron transport chain
series of electron carriers
26
what do pigment molecules do
absorb specific wavelengths of light and reflect others
27
what causes different colour and shades of leaves
due to the different combinations of pigments
28
where does the light independant reaction occur
in stroma
29
what impact does greater light intensity have on photophosphorylation ?
increase
30
what impact does greater light intensity have on ATP and NADPH production
increase
31
what impact does greater light intensity have on GP levels
remain the same or could increase
32
what impact does greater light intensity have on TP levels
increase
33
what impact does greater light intensity have on RuBP levels
increase
34
what impact does greater light intensity have on rate of photosynthesis overall
increase
35
what impact does lower light intensity have on photophosphorylation
decrease
36
what impact does lower light intensity have on ATP and NADPH production
decrease
37
what impact does lower light intensity have on GP levels
increase as can't turn GP into TP
38
what impact does lower light intensity have on TP levels
decrease
39
what impact does lower light intensity have on RuBP levels
decrease or stays the same
40
what impact does lower light intensity have on rate of photosynthesis overall
decrease
41
what might limit the carbon dioxide concentration that can be taken in through the stomata
if increase transpiration - windy conditions cause stomata to close so CO2 won't be taken in
42
what might limit the photosynthetic rate at high temperatures
enzyme denatures transpiration rate
43
photorespiration
oxygen competes with CO2 for the active site of rubisco leading to a decrease in the fixation of CO2
44
what impact does a higher carbon dioxide concentration have on carbon fixation
increases
45
what impact does a higher carbon dioxide concentration have on GP levels
increase
46
what impact does a higher carbon dioxide concentration have on TP levels
could increase but would need more ATP and NADH
47
what impact does a higher carbon dioxide concentration have on RuBP levels
stay same or increase
48
what impact does a higher carbon dioxide concentration have on overall rate of photosynthesis
increase
49
what impact does a lower carbon dioxide concentration have on carbon fixation
decrease
50
what impact does a lower carbon dioxide concentration have on GP levels
decrease
51
what impact does a lower carbon dioxide concentration have on TP levels
decrease
52
what impact does a lower carbon dioxide concentration have on RuBP levels
increase as will accumulate
53
what impact does a lower carbon dioxide concentration have on overall rate of photosynthesis
decrease
54
why might enzymes and proteins be affected by high temperature
enzyme active site denatures
55
why is a problem if plants don't do photosynthesis
can't produce TP
56
what is a compensation point
rate of respiration and rate of photosynthesis are equal
57
what is DCPIP
blue indicator that accepts electrons
58
what can DCPIP replace in the light dependant reaction
NADP
59
if DCPIP replaces NADP what happens
DCPIP turns from blue to colourless
60
explain how pairs of electrons move from chlorophyll to electron carrier system during part of the light-dependant reaction
chlorophyll a absorbs light energy and causes e- to be excited out and be accepted by electron carrier
61
how are electrons lost from chlorophyll replaced
photolysis of water occurs the H2O absorbs light and breaks down into O2 and H then the H splits into H+ and e-
62
explain how ATP is synthased when electrons pass through the atp synthase
electrons pass through and cause an electrochemical gradient so H+ ions move through the ATP synthase by chemiosmosis down a concentration gradient across the thylakoid membrane and causes a proton motive force the ADP and Pi joinn to form ATP
63
name the enzyme responsible for fixing CO2 in the light-independant stage
Rubisco
64
what is light intensity measured in
Lux
65
what is photorespiration
rubisco can bind to either O2 or CO2 in high temp O2 levels increase so O2 outcompetes the CO2 so less carbon fixation occurs
66
why are high temperatures a problem for C3 plants
abobe 25 degrees photorespiration exceeds photosynthesis as oxygenese activity of rubisco increases more than carboxylase activty so reduces rate of photosynthesis can also denature proteins also stomata may close due to high water loss so less CO2 enters plant
67
why aren't C4 plants affected as much by high temperatures
rubsico is only in the bundle sheath so CO2 from atmosphere binds to PEP carboxylase instead and then CO2 released from their is passed to rubisco
68

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