chapter 10- photosynthesis Flashcards

1
Q

what does photosynthesis do

A

convert solar energy into chemical energy

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2
Q

what is a thylakoid

A

structure inside the chloroplast

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3
Q

what is in the thylakoid membrane

A

photosynthetic enzymes and other molecules like pigments (chlorophyll)

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4
Q

where are chloroplasts found and in what quantity

A

found in mesophyll cells and there are 30-40 in each

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5
Q

what is the stroma

A

the fluid inside the chloroplasts

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6
Q

what are the characteristics/structures of thylakoids

A

thylakoids are stacked in structures called grana
the interior thylakoid membranes form interconnected sacs
chlorophyll is present in the membranes and makes them green

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7
Q

photosynthesis formula

A

6co2 + 12h2o + E -> c6h12o6 +6o2 +6h2o

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8
Q

water is fully oxidized to what

A

oxygen gas

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9
Q

co2 is reduced to what

A

oxygen in water
oxygen in sugar
carbon in sugar

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10
Q

light as behaves as discrete particles called

A

photons

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11
Q

what is an absorption spectrum

A

a pigment’s light absorption vs wavelength

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12
Q

what is chlorophyll a’s absorption spectrum related to photosynthesis

A

suggests that violet-blue and red wavelengths work better

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13
Q

what is an action spectrum

A

shows the effects of different wavelengths on a process

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14
Q

what is the main photosynthetic pigment

A

chlorophyll a
absorbs better

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15
Q

what do chlorophyll b and carotenoids do light-wise

A

chlorophyll b broadens spectrum used for photosynthesis
carotenoids absorbs the excessive light that can damage chlorophyll

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16
Q

explain the excitation of chlorophyll by light

A
  1. pigment absorbs light and goes into excited/unstable state
  2. electrons fall back to ground state
  3. electrons can be released as photons of light or heat
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17
Q

photons of light are described as

A

fluorescence

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18
Q

what is a photosystem

A

a reaction-centre complex surrounded by light-harvesting complexes
donut is light-harvesting, hole is reaction centre

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19
Q

what are light-harvesting complexes

A

pigments bound to proteins

20
Q

what do light-harvesting complexes do

A

transfer photon energy to reaction centre

21
Q

what are the components of a photosystem

A

reaction-centre complex
- primary electron acceptor
- special pair of chlorophyll a
light-harvesting complexes
- pigment molecules

22
Q

how does a photosystem function

A

light harvested is transferred to the pair of chlorophyll a
electron is transferred to primary electron acceptor

23
Q

what are the two types of photosystems in thylakoid membranes

A

PSII/P680
PSI/P700

24
Q

why are they named P680 and P700

A

P680 because chlorophyll a absorbs wavelengths 680nm best
P700 because thats the wavelength that it absorbs at

25
Q

what are the types of light reactions

A

linear electron flow
cyclic electron transport

26
Q

what are the steps of linear electron flow (6)

A

light goes into PSII
2 electrons go into PSII from h2o and 2 hydrogens and 1/2 o2 are released
electrons are transported through the electron transport chain to PSI and cause an energy release
energy is used to move protons across membrane (drives atp production)
light goes into PSI
electrons fall and are transferred to NADP+ creating NADPH

27
Q

which part of linear electron flow happens where

A

PSII -> ETC happens in the thylakoid space
PSI happens in stroma

28
Q

after the linear electron flow happens what are the pH of the components of the chloroplasts

A

the thylakoid space is more acidic
the stroma is more basic

29
Q

what are the steps of cyclic electron transport

A

light enters PSI
2 electrons move to the primary electron acceptor
hydrogen ions are pumped out
atp is produced
2 electrons reenter the PSI

30
Q

where does the calvin cycle take place

A

stroma

31
Q

what are the three phases of the calvin cycle

A

carbon fixation
reduction
regeneration of RuBP

32
Q

what are the steps of carbon fixation in the calvin cycle

A
  1. 3 RuBP + 3 co2 are catalyzed by rubisco and form a c6 intermediate
  2. 6 PGA are formed
  3. 6 atp are used for their phosphate group (6 adp are released)
  4. 6 NADPH are used for the H (6 NADP+ and 6 inorganic phosphates are released)
33
Q

what does RuBP stand for

A

ribulose biphosphate
c5

34
Q

what does PGA stand for

A

phosphoglycerate acid
c3

35
Q

what are the steps of reduction in the calvin cycle

A
  1. 6 G3P are formed
  2. 1 G3P is released
36
Q

what does G3P stand for

A

glyceraldehyde 3-phosphate
c3

37
Q

what are the steps of regeneration of RuBP in the calvin cycle

A
  1. 5 G3P are used
  2. 3 atp are used for their phosphate groups (3 adp are released)
  3. 3 RuBP are released
38
Q

what type of molecule is G3P

A

a sugar

39
Q

what is photorespiration

A

the interaction between RuBP and oxygen with rubisco to catalyze

40
Q

how does photorespiration happen

A

when oxygen gas builds up and there is a limited amount of co2
due to stomata being closed on hot and dry days

41
Q

details of photorespiration

A

oxygen is a competitive inhibitor to co2 for the active site of rubisco (o2 and co2 have similar shape)
o2 doesnt add to carbon chain so no sugar is produced during photosynthesis and plant doesnt grow, instead releases co2 with no atp

42
Q

advantage and disadvantage of photorespiration

A

can limit damaging product of light reactions
can drain up to 50% of carbon from calvin cycle

43
Q

how do c4 plants minimize the cost of photorespiration

A

they put co2 into a c4 compound and the increase the co2 concentrations near rubisco using distinct cell types in their leaves

44
Q

types of cells in c4 plants leaves

A

mesophyll cells
bundle-sheath cells

45
Q

steps of sugar production in c4 plants

A
  1. co2 is trapped by PEP carboxylase and creates a c4 compound (oxaloacetate) with PEP (c3) in mesophyll cell
  2. c4 travels to bundle-sheath cell
  3. c3 compound is released and co2 enters calvin cycle
46
Q

what is CAM

A

crassulacean acid metabolism
used to fix carbon

47
Q

how does CAM work

A

stomata open at night, co2 is incorporated into c4 organic acids
stomata close during the day, co2 is released and used in calvin cycle