c1.2 - photosynthesis Flashcards

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1
Q

chloroplast

A

organelle found in plants + green algae
site of photosynthesis

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2
Q

structure of chloroplast

A

double membrane
grana - stacks of flattened disks (thylakoid) contains ps1 + ps2, ETC, atp synthase
grana connected by intergranal lamellae
stroma
- fluid filled matrix contains enzymes

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3
Q

where are chloroplasts located in angiosperm leaf

A

mainly in palisade layer

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4
Q

chloroplast adaptations for photosynethis

A
  • thylakoids give large SA for light independent reactions
  • photosynthetic pigments affra ged in photosys5ems to maximise light absorption
  • stroma directly surrounds grana = products of photosynthesis diffuse directly into stroma
  • contain DNA + ribosomes
    inner membrane less permeable than outer, enabling control over movement of substances
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5
Q

angiosperm leaf adaptations for photosynthesis

A
  • large SA to maximise light absorption
  • think to reduce diffusion distance for co2
  • upper epidermis transparent allowing light to strike mesophyll layers
  • palisade cells densely packed + contain many chloroplasts
  • air spaces reduce diffusion distance for co2
  • vein network transports water + minerals to lead to+ takes sugars away
  • stomata allow co2 to diffuse into leaf
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6
Q

transducer, why are chloroplasts described as transducers

A
  • something converts one type of energy into another
  • transduce light energy into chem energy of ATP
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7
Q

photosynthetic pigment

A

molecule present in chloroplasts that absorb light energy for photosynthesis
absorbs specific light wavelengths c reflects ithers

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8
Q

examples of photosynthetic pigments

A
  • chlorophyll a+b
  • carotenoids
  • xanthophylls
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9
Q

why range of photosynthetic pigments

A

absorbs range of light wavelengths

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10
Q

purpose of chromatography

A

separates different products from a mixture of

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11
Q

equation used to calculate Rf

A

distance travelled by component
Rf = ————————————————
distance traveled by solvent

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12
Q

photosynthesis

A

complex metabolic pathway that synthesises organic molecules from co2 + water in presence of light
6CO2 + 6H2O -> C6H12O6 + 6O2

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13
Q

stages of photosynthesis

A

light dependent
light independent

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14
Q

photosystem

A
  • protein complex consisting of antennae complex + reaction centre
  • involved in absorption of light + transfer of electrons in photosynthesis
  • two types: ps1 + ps2
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15
Q

difference between ps1 + ps2

A

absorb different light wavelengths

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16
Q

process of light harvesting

A
  • antennae complex absorbs light energy of varying wavelengths + transfers it quickly and efficiently to reaction centre
  • energy absorbed by two chlorophyll a molecules which emit excited electrons
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17
Q

absorption spectrum

A

pattern of bands that occurs when a substance absorbs different wavelengths of light

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18
Q

action spectrum

A

graph of rate of photosynthesis against each light absorbed by a pigment

19
Q

light dependent stage

A
  • first stage of photosynthesis
  • takes place in thylakoids of chloroplast
  • uses light energy t9 produces ATO, reduced NADP, and O2
20
Q

sources of electrons for ETC

A

cyclic + non-cyclic photophosphorylation

21
Q

cyclic photophosphorylation

A

formation of ATP involving ps1 only, where NADP is not reduced

22
Q

outline cyclic photophosphorylation

A
  • involves ps1 only
  • excited electrons enter ETC.to produce ATP then return to ps1
  • no reduction of NADP + no water required to replace lost electrons
23
Q

purpose of cyclic photophosphorylation

A

produces additional ATP to meet surplus energy demands of cell

24
Q

non cyclic photophosphorylation

A

formation of ATP + reduced NADP involving ps1 and ps2

25
Q

outline non cyclic photophosphorylation

A
  • involves ps1 + ps2
  • excited electrons nested ETC to produce ATP
  • NADP acts as final electron acceptor + is reduced
  • water is photolysed to compensate for electrons lost for ps2
26
Q

purpose of non cyclic photophosphorylation

A

produces ATP + reduced NADP for calvin cycle

27
Q

how does chemiosmosis produce ATP in lds

A
  • protons flow down conc gradient from thylakoid space into stroma via ATP synthase
  • ATP synthase phosphorylates ADP to form ATP as protons flow through it
28
Q

photolysis

A

splitting of molecule of water in presence of light that occurs in lds
produces protons, electrons, and o2
H2O -> 2H+ + 2e- + 1/2O2

29
Q

what happens to products of photolysis

A

H+ - used in proton pumping and to reduce NADP
e- - replace electrons lost from chlorophyll a in ps2
O2 - byproduct, used for respiration or diffuses out of leaf as waste gas

30
Q

how ETC results in production of reduced NADP

A

NADP acts as final electron acceptor
subsequently reduced

31
Q

LIS of photosynthesis

A
  • second stage of photosynthesis
  • calvin cycle produces glucose
  • doesn’t require light energy + takes place in stroma
  • uses CO2 + products of LDS to build organic. ole uses
32
Q

what is LIS also known as

A

calvin cycle

33
Q

main stages of calvin cycle

A
  • carbon fixation
  • reduction
  • regeneration
34
Q

carbon fixation of calvin cycle

A
  • reaction between CO2 + RuBP catalysed by enzyme RuBisCo
  • forms unstable 6C intermediate that breaks down into 2 molecules of G3P
35
Q

reduction of calvin cycle

A
  • 2 G3P reduced to 2 TP
  • requires 2 reduced NADP + 2 ATP formed during LDS
  • forms 2 NADP + 2 ADP that enter LDS
36
Q

regeneration of calvin cycle

A
  • after 1C leaves cycle, 5C compound forms
  • RuBP regenerated from 5C usuing 1 ATP
  • forms 1 ADP
37
Q

how are nutrients produced as a result of photosynthesis

A
  • formation of amino acids for GP (requires nitrates + sulfates)
  • TP molecules used to produce sugars
    e.g: glucose, fructose, sucrose
38
Q

limiting factor

A

variable that limits rate of reaction

39
Q

limiting factors in photosynthesis, what stage limited

A

light intensity - LDS
light wavelength- absorption by chlorophyll
CO2 concentration - LIS
temp - enzyme controlled reactions (carbon fixation)
pH - enzyme controlled reactions

40
Q

role of nitrogen in plant metabolism

A

synthesis of amino acids, nucleotides, + chlorophyll

41
Q

what does nitrogen deficiency in plants cause

A
  • stunted growth
  • chlorosis (yellowing of leaves due to insufficient chlorophyll production)
42
Q

role of magnesium in plant metabolism

A

central component of chlorophyll

43
Q

what does magnesium deficiency in plants cause

A

chlorosis (yellowing of leaves due to insufficient chlorophyll production)