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Biology - Module 5 > Photosynthesis > Flashcards

Photosynthesis Flashcards

(57 cards)

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1
Q

compare photosynthesis + aerobic respiration + anaerobic respiration

where it occurs

energy

conversion of energy

anabolic or catabolic

overall equation

how ATP is produced

coenzyme used

A
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2
Q

describe how ATP is synthesised

A

electrons excited

pass through electron transport train

energy released

+ used to pump protons across membrane

creates conc gradient

protons diffuse back through membrane down conc - CHEMIOSMOSIS

diffuse via hydrophilic transmembrane channels linked to ATP synthase

flow of protons provide energy needed to make ATP from ADP + Pi

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3
Q

what is chemiosmosis

A

Diffusion of protons from region of high concentration to region of low concentration

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4
Q

what does chemiosmosis result in

A

Movement of protons down gradient released energy used in attaching phosphate ion to ADP forming ATP

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5
Q

how are electrons excited

A

Electrons present in pigment molecules – chlorophyll – are excited by absorbing light

High energy electrons released when chemical bonds are broken in respiratory substrate molecules

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6
Q

what is the electron transport chain

A

Made up of electron carriers – progressively lower energy levels

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7
Q

how large are chloroplasts

A

2 – 10 micrometres in diameter

larger than mitochondria

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8
Q

describe the structure of chloroplasts

A

Surrounded by double membrane

Have cytosol-like fluid – stroma

Has separate system of membranes

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9
Q

describe the double membrane

A

Outer – permeable to ions / small molecules

Inner – has transport proteins

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10
Q

what is in the stroma

A

Carbon dioxide / sugars / enzymes

Has 70s ribosomes + loop of DNA + starch grains

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11
Q

describe the separate membrane system

A

has flattened fluid-filled sacks = thylakoids

Thylakoid membrane – has pigments / enzymes / electron carriers

Thylakoids stack to form grana

Grana connected by membranous channels – lamellae

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12
Q

what is the purpose of lamellae

A

Ensure sacs are connected but distanced from each other

Membrane of grana – large SA

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13
Q

how is the stroma adapted for photosynthesis

A

Gel-like fluid

Enzymes for light-independent reactions

Surrounds grana and membranes

Facilitates rapid transport of products from light-dependent stage

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14
Q

how is the grana adapted to photosynthesis

A

Stacks of thylakoids

Large surface area

Presence of many photosystems

Maximizes light absorption

More membrane space for electron carriers and ATP synthase enzymes

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15
Q

how are the ribosomes adapted for photosynthesis

A

Present in chloroplast

Allows translation of proteins coded by cpDNA

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16
Q

how is the inner membrane adapted for photosynthesis

A

Selective transport proteins

Control flow of molecules between stroma and cytosol

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17
Q

what are the two types of pigments

A

chlorophylls

carotenoids

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18
Q

what are the two types of chlorophyll

A

chlorophyll a

chlorophyll b

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19
Q

what are the two types of carotenoids

A

beta carotene

xanthophyll

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20
Q

what are the colours of the chlorophyll pigments

A

chlorophyll a - yellow-green

chlorophyll b - blue-green

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21
Q

what are the colours of the carotenoids pigments

A

beta carotene - orange

xanthophyll - yellow

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22
Q

what wavelengths do chlorophyll absorb + reflect

A

absorb wavelengths in blue-violet + red regions

reflect green light

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23
Q

what wavelengths do carotenoids absorb

Study These Flashcards
A

absorb wavelength’s in blue-violet regions

24
Q

what is a photosystem

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A

??

Light harvesting system + reaction centre

25
what is the role of a photosystem
to absorb / harvest light energy + transfer energy quickly to reaction centre
26
where are the photosystems found
In the membrane of thylakoids
27
what are the two photosystems
Photosystem 1 (P700) Photosystem 2 (P680)
28
what is the max absorption of photosystem 1
700nm
29
what is the max absorption of photosystem 2
680nm
30
what are the two stages of photosynthesis
light dependant light independant - calvin cycle
31
what happens overall in the light dependant stage
Energy from sunlight absorbed + used to form ATP Hydrogen from water used to reduce coenzyme NADP to reduced NADP
32
where does the light dependant stage occur
Thylakoid membrane
33
what process does the light dependant stage occur via
noncyclic or cyclic photophosphorylation
34
describe non cyclic photophosphorylation
Light absorbed by PS2 PS2 has oxygen evolving complex – water splitting enzyme Breaks down water - photolysis = H2O → 2H+ + 2e- + ½O2 Photon collides with chlorophyll a + excites an electron in a Mg atom (photoionisation) As electrons leave PS2 – replaced by electrons from photolysis excited electrons pass down electron transport chain H+ transported to stroma by ATP synthase Chemiosmosis + photophosphorylation Electron passes from electron transfer chain to PS1 Electrons excited at PS1 in Mg atom - photoionisation New electron goes through electron carrier 2 + replaced by electron coming from electron carrier 1 (PS2) Electrons combine with H+ and NADP to get reduced NADP (NADPH
35
describe chemiosmosis again
As high energy electrons move through carriers – energy released Energy used to pump protons across membrane from stroma to thylakoid lumen= making conc gradient Gradient maintained from permeability of membrane to hydrogen ions NOW - only way protons move back through membrane DOWN conc gradient is through membrane channels linked to ATP synthase Facilitated diffusion of protons provides energy used to make ATP from ADP + Pi
36
what are the end products of non cyclic photophosphorylation
Used water Produced oxygen as a biproduct Produced NADPH + ATP
37
describe cyclic photophosphorylation
Only involves PS1 Times of stress Rather than end result of NADPH – electron passed back to PS2 from PS1 Re-enters electron transfer chain Keep pumping H+ into thylakoids = produce more ATP NO reduced NADPH produced
38
state the difference between cyclic + non cyclic photophosphorylation
?
39
where does the light independant stage occur
stroma
40
describe the calvin cycle
Carbon dioxide enters intercellular spaces in spongy mesophyll via diffusion through stomata Diffuses into stroma of chloroplasts Combined with ribulose biphosphate (RuBP) Carbon dioxide is now fixed – incorporated into organic molecule Six carbon unstable intermediate produced Breaks down – 2 three carbon glycerate 3-phosphate (GP) molecules Each GP reduced into another 3 carbon – triose phosphate (TP) Uses hydrogen from NADPH + energy from ATP TP – carbohydrate + majority recycled to regenerate RuBP Regeneration uses ATP
41
draw out the calvin cycle
42
what is the fixation of carbon dioxide
Combining with ribulose biphosphate (RuBP
43
what is RuBP
5 carbon sugar ribulose biphosphate
44
what is the fixation of carbon dioxide catalysed by
Catalysed by ribulose biphosphate carboxylase (RuBisCO)
45
whats bad aboutn RuBisCo
Carbon dioxide is now fixed – incorporated into organic molecule
46
what needs to happen in the calvin cycle for 1 glucose molecule to be made
six carbon dioxide molecules have to enter 6 full turns of the cycle make 12 TP molecules – 2 of which will be removed to make the glucose molecule 10 TP molecules recycled to make 6 RuBP
47
what are the uses of TP
Can condense to form hexose phosphate – used to produce starch / sucrose / cellulose Can be converted into glycerol Used to make amino acids
48
state the factors effecting rate of photosynthesis
light intensity carbon dioxide conc temperature
49
how does light intensity effect rate of photosynthesis
Rate of photosynthesis increases as light intensity increases Greater light more energy supplied to plant Faster light dependant stage can occur Produces more ATP + NADH for Calvin cycle
50
state the relationship between decreasing light intensity and the conc of NADH / GP / TP / RuBP
Decrease light intensity = decreases conc of TP + RuBP BUT slight increase in GP
51
how does decreasing light intensity effect conc of NADH / GP / TP / RuBP
Decrease light intensity = decrease in TP + RuBP BUT slight increase in GP Less light – light dependant stops + doesn’t form any more products (ATP + NADH) GP builds up as it is not converted to TP Lack of TP – RuBP wont form Overtime fixation of carbon dioxide will stop + GP conc will plateau
52
how does carbon dioxide conc increase rate of photosynthesis
rate of photosynthesis increases as carbon dioxide concentration increases More carbon dioxide.. more combined with RuBP + faster Faster Calvin cycle + faster rate of photosynthesis
53
state the relationship between decreasing carbon dioxide conc and the conc of NADH / GP / TP / RuBP
Low conc of carbon dioxide – decrease in conc of GP + TP but increase in RuBP
54
how does decreasing carbon dioxide conc effect conc of NADH / GP / TP / RuBP
Low conc of carbon dioxide – decrease in conc of GP + TP but increase in RuBP RuBP accepts carbon dioxide so when there is a lack it remains unfixed + builds up Prevents TP + GP from forming
55
why doesnt temp have a significant effect on the light dependant stage
driven by light energy rather than kinetic energy
56
how does increasing temp effect rate of photosynthesis
Increasing temp – cause stomata to close – carbon dioxide cant be fixed + slow rate down Light dependant reaction relied on proton gradient forming across thylakoid membrane = membrane permeability influenced by extreme temp
57

Biology - Module 5 (8 decks)

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