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BIOL 1020 > photosynthesis- lecture #12 > Flashcards

photosynthesis- lecture #12 Flashcards

1
Q

what is the origin of all energy?

A

solar power

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2
Q

what are chloroplasts responsible for in photosynthesis?

A

capture of light energy

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3
Q

what organic materials are needed for cell activities?

A

carbohydrates, proteins, lipids, nucleic acid

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4
Q

where can carbon originate from?

A

carbon dioxide and organic sources

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5
Q

what is autotrophic nutrition? what uses this?

A

can fix their own carbon
carbon dioxide uses this
plants

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6
Q

what is heterophic nutrition? what uses heterotrophic nutrition?

A

can’t make carbon themselves, need carbon to be given to them
organic sources use heterophic nutrition

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7
Q

how do organic sources obtain carbon?

A

through decomposition (fungi, bacteria) or direct consumption

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8
Q

how do photoautotrophs work?

A

use light energy to synthesize organic compounds

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9
Q

what are photoautotrophs? examples

A

algae, protists, cyanobacteria

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10
Q

what is a redox reaction?

A

movement of electrons from water to carbon dioxide forming sugar

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11
Q

what happens to potential energy in a redox reaction? is it endergonic or exergonic?

A

potential energy of the electrons are increased along the way
endergonic reaction

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12
Q

what makes a redox reaction endergonic?

A

takes energy from the sun

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13
Q

what are 2 stages of photosynthesis?

A

light reactions
dark reactions (calvin cycle)

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14
Q

where did photosynthesis begin? what does photosynthetic bacteria consist of?

A

began in photosynthetic bacteria
highly folded plasma membrane
same structure as a chloroplast membrane

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15
Q

how can you re energize H2O

A

by using electrons

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16
Q

what are veins function in leaves?

A

veins export sugar to the roots and other non- photosynthetic structures
(responsible for transport)

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17
Q

why is it important for leaves to be flat?

A

to capture as much of the light energy from the sun as possible

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18
Q

why are chlorophyll pigments concentrated? what do they do?

A

provides characteristic green color and absorbs light energy

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19
Q

what drives photosynthetic reactions?

A

light absorption by chlorophyll

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20
Q

what is the photosynthesis equation

A

6CO2 +12H2O + light energy —> C6H12O6 + 6O2 + 6H2O

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21
Q

what is glucose assembled from?

A

2 three carbon intermediates

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22
Q

why is the inner membrane of chloroplasts not folded?

A

because we don’t put proteins in it

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23
Q

do chloroplasts have high or low SA

A

high SA because of the grana that are stacked inside

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24
Q

how does sunlight lift electrons? analogy

A

when you use a hammer and a bell at a fair, you put your energy into it and it increases potential energy

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25
Q

what does photosynthesis use as a reactant and also a product

A

water

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26
Q

where does O2 generated from photosynthesis come from?

A

water molecules

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27
Q

how many water molecules are needed to produce O2

A

need 2 H2O in order to produce O2

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28
Q

where do light reactions take place?

A

thylakoid membrane (the photo stage)

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29
Q

what is water split into? what does it release?

A

water is split into 2 protons and 2 electrons
releasing oxygen

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30
Q

what is the light absorbed by chlorophyll used to do?

A

used to power the transfer of electrons from water to NADP+

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31
Q

how is ATP produced in light reactions?

A

solar energy is converted into ATP
chemiosmosis produces ATP

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32
Q

what is the process of chemiosmosis in photosynthesis?

A

light energy is converted to chemical energy in the form of ATP to be used in dark reactions

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33
Q

what are dark reactions?

A

carbon fixation step

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34
Q

do light and dark reactions take place in daylight?

A

yes, but dark reactions do not require light

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35
Q

where do we store pigments?

A

thylakoid because it has good memory

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36
Q

what is an example of electromagnetic radiation?

A

sunlight

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37
Q

how does electromagnetic radiation travel?

A

in waves that have electrical and magnetic properites

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38
Q

what is wavelength?

A

the distance between crests

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39
Q

how is wavelength related to energy

A

inversely related to energy
shorter wavelength, higher energy

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40
Q

what are photons?

A

discrete particles of light, each has a fixed quantity of energy

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41
Q

what happens when light interacts with matter?
___,___,___

A

it can be reflected, absorbed or transmitted

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42
Q

what do pigments serve to absorb?

A

light energy
light must be absorbed if it can be used to perform work

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43
Q

what are the 3 pigments in chloroplasts?

A

chlorophyll a
chlorophyll b
carotenoids

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44
Q

what does chlorophyll a do?

A

participates directly in the light reactions
prevents waste

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45
Q

what does chlorophyll b do?

A

an accessory pigment

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46
Q

what are carotenoids?

A

group of accessory pigments

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47
Q

what is the least effective color?

A

green, because it is reflected
can’t be absorbed/ used to perform work

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48
Q

what do accessory pigments allow?

A

allow absorption of an increased number of wavelengths

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49
Q

what allows for increased absorption between pigments?

A

small structural differences

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50
Q

what type of light does chlorophyll a have?

A

chlorophyll a: blue green light

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51
Q

what type of light does chlorophyll b have?

A

chlorophyll b: olive green light

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52
Q

what type of light does carotenoids have? what does this light do?

A

carotenoids: yellow/orange light
serve as photo-protectants
absorb and dissipate energy

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53
Q

why are there 3 different types of pigments?

A

because you can’t do everything on your own
chlorophyll a gets everything from the other pigments
therefore, chlorophyll b and carotenoid are the people you hire to do stuff for you

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54
Q

what happens when pigments absorb light?

A

increased potential energy, excites electron to another orbital

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55
Q

how does an electron reach the excited state, what happens after the excited state?

A

photon is absorbed –> charges electron with light —> boosts the electron to an excited state –> electron drops back to the ground state quickly –> absorbs longer waves and releases

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56
Q

what is excess energy from electrons released as?

A

heat or light (fluorescence)
wasted light

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57
Q

what is a photosystem? what does it consist of?

A

reaction centre complex
a pair of chlorophyll a and light harvesting complexes

58
Q

what does increased variety of pigment allow?

A

allows energy harvesting to occur over a greater SA and an increased spectrum of absorption

59
Q

process of photon to center complex

A

photon strikes pigment
pigment reaches excited state
pigment transfers energy from pigment to pigment
gives energy (electron) to chlorophyll a
chlorophyll a gives electrons to reaction center

60
Q

process of photon to center complex analogy

A

you strike the hammer on the plate
bell inside reaches the top (excited state)
as bell goes down theres a decrease in energy
the energy thats left would be given to chlorophyll a
chlorophyll a gives electrons to reaction center

61
Q

chlorophyll a converts what type of energy to what type of energy?

A

converts light energy to chemical energy
(redox reaction)

62
Q

what photosystems do thylakoids have

A

photosystem PSII and PSI

63
Q

what wavelength does PSII and PSI have?

A

PSII: P680
PSI: P700

64
Q

what comes first, PSI or PSII

A

PSII but has a shorter wavelength so remember it that way

65
Q

what happens as the electron falls back down?

A

energy release stimulates excitation of a nearby electron

66
Q

how long does the process of the electron continue for in photosystem II?

A

until the chlorophyll a pair of P680 is reached

67
Q

what does P680 look like when its excited?

A

P680*

68
Q

when P680 is excited H2O splits into what? what helps H2O do this?

A

H2O is split into 2H+, 2e- and O
assistance of an enzyme

69
Q

what does photosynthesis use? (3)

A

H2O, CO2 and sunlight

70
Q

what does photosynthesis create?

A

O2 organic compounds

71
Q

where are photosynthetic pigments located?

A

thylakoid membrane

72
Q

what are the products of light reactions?

A

NADPH, O2, ATP

73
Q

what is the terminal electron acceptor in the light reactions of photosynthesis?

A

NADP+

74
Q

Molecular oxygen (O2) produced in the light reactions originates where?

A

H2O

75
Q

During the dark reactions of photosynthesis, electrons begin on_______and end up on ________

A

NADPH and CO2

76
Q

the transfer of electrons from P680* to P700 is what type of reaction?

A

exergonic and coupled to the transfer of protons from the stroma into the thylakoid lumen

77
Q

plants use sugars produced in the dark reactions to build what? ____,____,____

A

lipids, proteins and other important molecules in the cell

78
Q

When H2O splits int 2H, 2e- and O, what are the electrons used for?

A

used to replace the donated pair from P680

79
Q

what happens to H+ when H2O is split?

A

goes to the thylakoid lumen, creates a strong H+ gradient then goes through chemiosmosis (ATP synthase) to create ATP to be used in the calvin cycle

80
Q

What happens to oxygen when water is split?

A

it gets released, in which we use to breath

81
Q

what happens after electrons go from P680 to P680*? what happens next?

A

transferred via an electron transport chain (to get to photosystem I)

82
Q

what does the electron transport chain consist of?

A

plastoquinone, cytochrome complex and plastocyanin

83
Q

the fall of electrons going through photosynthesis is what type of reaction?

A

exergonic

84
Q

what gets pumped through the electron transport chain into the lumen?

A

H+, to go to the ATP synthase to create ATP

85
Q

the light harvesting complex transfers light where?

A

photosystem I

86
Q

what happens in photosystem I?

A

the electrons of P700 are replaced with the electrons moving from PSII down the electron transport chain
photons also get absorbed

87
Q

where does P700* pass electrons to?

A

moves down a second electron transport chain

88
Q

what does the second electron transport chain use?

A

ferredoxin

89
Q

what does the second electron transport chain do?

A

transfers electrons to NADP+ forming NADPH

90
Q

is NADP+ an electron donor or acceptor?

A

acceptor

91
Q

where does the NADPH get brought to?

A

calvin cycle (to be used later)

92
Q

what is more energized, NADPH or H2O? why?

A

NADPH because more energy is released

93
Q

why are light reactions called the z scheme?

A

in the form of a Z going through photosystem II, ETC and photosystem I

94
Q

what does the cyclic electron flow consist of?

A

electrons move from ferredoxin to cytochrome complex to P700 in PSI (they get recycled)

95
Q

is PSII ever used in cyclic electron flow?

A

never, only PSI

96
Q

what is not released (2) and produced (1) in the cyclic electron flow?

A

no NADPH released
no O2 released
ATP is produced

97
Q

why does the cyclin electron flow need to occur? (3)

A

to generate ATP
to recharge
to protect photosystem I and II against photoinhibition

98
Q

what is the equation for dark reactions?

A

NADPH + ATP + CO2 –> glucose

99
Q

what type of reaction is the calvin cycle? (catabolic or anabolic)

A

anabolic
creates order
non-spontaneous

100
Q

what is the reducing power that the calvin cycle uses?

A

NADPH

101
Q

what is G3P?

A

glyceraldehyde 3 phosphate (calvin cycle doesnt directly produce glucose, it produces G3P)

102
Q

what are the 3 phases of the calvin cycle?

A

phase I: carbon fixation
phase II: reduction
phase III: ribulose bis-phosphate regeneration

103
Q

what occurs during carbon fixation?

A

RuBP + CO2 are catalyzed by an enzyme called RUBISCO to form a 6 carbon intermediate

104
Q

what does the 6 carbon intermediate do?

A

splits into 2 x 3-phosphoglycerate
(because the intermediate is very unstable

105
Q

what is the first step of reduction?

A

3 phosphoglycerate accepts a phosphate form ATP forming 1,3 bis- phosphoglycerate (1,3 PGA)

106
Q

what does 1,3 bisphosphoglycerate (1,3 PGA) do?

A

accepts 2 electrons from NADPH and releases one phosphate group

107
Q

when 1,3 bisphosphoglycerate (1,3 PGA) accepts 2 electrons what does it form?

A

glyceraldehyde 3-phosphate (G3P)
(has more potential energy)
(also formed in glycolysis)

108
Q

in the reduction phase for every 3 turns of the calvin cycle what is produced?

A

6 G3P

109
Q

with the 3 cycles in reduction how many carbons have been consumed?

A

15 carbon from RUBISCO

110
Q

in the III phase of the calvin cycle what is rearranged? what does this process require?

A

5x G3P are rearranged into 3x RuBP
(requires 3 ATP)

111
Q

what does the net synthesis of one G3P require?

A

9 ATP and 6 NADPH
ATP and NADPH are products of the light reactions

112
Q

on hot days what form is the stromata in?

A

stomata are closed

113
Q

why are stomata closed on hot days?

A

prevents water loss

114
Q

by preventing water loss what else simultaneously decreases?

A

CO2 intake and therefore increased O2 release from the light reactions

115
Q

in respect to photorespiration what plants make G3P first?

A

C3 plants

116
Q

in photorespiration, RUBISCO can bind to what?

A

O2 as well as CO2

117
Q

what is the most abundant protein on earth?

A

RUBISCO

118
Q

when RUBISCO binds to O2 or CO2 what compound is produced?

A

2 carbon

119
Q

what is consumed and released during photorespiration?

A

O2 is consumed, peroxisomes and mitochondria rearrange the compound and CO2 is released

120
Q

does photorespiration consume or produce ATP?

A

consumes

121
Q

what do C4 plants produce?

A

4 carbon intermediate

122
Q

what is the unique leaf anatomy in C4 plants?

A

bundle sheath is arranged around the veins of the leaf (between vein and mesophyll)

123
Q

where does the C4 plant relocate CO2?

A

from mesophyll (oxygenated) to bundle sheath (no oxygen)

124
Q

what is the process of CO2 being relocated to the bundle sheath an example of?

A

alternative to carbon fixation

125
Q

what does the enzyme PEP carboxylase do in the alternative to carbon fixation?

A

combines PEP with CO2 forming a 4 carbon intermediate called oxaloacetate

126
Q

what has a higher CO2 affinity, PEP carboxylase or Rubisco?

A

PEP carboxylase (because it does not have O2 affinity allowing for efficient CO2 fixation in hot, dry climates)

127
Q

what does the mesophyll do with the 4 carbon intermediate product?

A

exports it to the bundle sheath cells via plasmodesmata

128
Q

what happens to the 4 carbon intermediate in the bundle sheath cells?

A

it loses CO2 therefore is used as a substrate for Rubisco

129
Q

the remaining 3 carbon molecule pyruvate is converted back to ___ at a cost of one ___ molecule

A

PEP at a cost of one ATP molecule
(the price required to increased the CO2 concentration in the bundle sheath cell)

130
Q

the high CO2 concentration keeps Rubisco from binding to ___ which minimizes photorespiration

A

O2

131
Q

in CAM plants photosynthesis adapts to what?

A

hot climates
(example is cacti)

132
Q

in CAM plants is stomata open or closed?

A

open at night and closed during the day (helps to conserve water)

133
Q

what do CAM plants prevent from entering?

A

CO2

134
Q

once equilibrium of CO2 has been reached in CAM plants, where is the CO2 stored?

A

into organic acid

135
Q

what does photosynthesis produce? (2)

A

chemical energy and carbon skeletons

136
Q

what is chemical energy used to make?

A

all major organic molecules of plant cells
(50% is stored as fuel for cellular respiration)

137
Q

leaves are autotrophic, what does that entail?

A

the remaining plant structures receive organic carbon structures via the veins (usually as sucrose)

138
Q

organic carbon is delivered to other cells for what? (2)

A

cell respiration and anabolic reactions

139
Q

glucose is stored as starch, what is starch to photosynthesis?

A

main ingredient of the plant cell wall
we use glucose

140
Q

where is excess sugar stored in plants?

A

roots, seeds and fruits

141
Q

sap transport is bidirectional, what does that mean?

A

sap goes up into the leaf through the roots
sap goes down the leaf simultaneously

142
Q

how many metric tons of carbohydrates do plants produce per year?

A

160 billion metric tons

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