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3.5.1 Photosynthesis Flashcards

3.5.1 Photosynthesis

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1
Q

what are the two main stages of photosynthesis

A

light dependant reaction
light independant reaction / kelvin bensin cycle

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2
Q

what is the gcse general equation for photosynthesis

A

6CO2 + 6H2) —-(light)—> C6H12O6 + 6O2

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3
Q

draw out a chloroplast with labbels

A

check with photosynthesis pack

https://stock.adobe.com/images/chloroplast-structure-with-titles/185026077

should include :

outer membrane
intermembrane space
inner membrane
stroma (aqueous fluid)
granum (stack of thylakoids)
thylakoids
lamella
lumen (inside of thylakoid)

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4
Q

what do thylakoids do, and when are they used LDR or LIR

A

Thylakoids contain chlorophyll and other pigments that can
absorb light at a variety of wavelengths (light dependent reactions)

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5
Q

what are starch grains used for

A

Starch grains store excess carbohydrates made in photosynthesis.

you test starch with an iodine solution

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6
Q

what are ribosomes used for in a chloroplast

A

Ribosomes for protein synthesis

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7
Q

why is granum useful for

A

Granum is a stack of thylakoids. Stacking thylakoids maximises surface area for light capture

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8
Q

what is the purpose of stroma , and when is it used LIDR or LDR

A

Stroma contains enzymes for light-independent reactions

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9
Q

which stage uses water and produces oxygen

A

kight dependant reaction

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10
Q

which stage reduces carbon dioxide to produce glucose

A

light INdependant reaction

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11
Q

what two key products are produced in light dependant reaction

A

ATP

and

NADPH

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12
Q

what two key products are produced in light independant reaction

A

suger
water

also:
NADP+
ADP

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13
Q

where does the does the light dependent reaction take place

A

in the lumen of the thylakoid

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14
Q

what two pigments does a plant have and what type of wave length of light do they reflect

A

chlorophylls (primary pigments)
carotenoids (accessory pigments).

Chlorophyll is the pigment that gives plants their green colour by reflecting green light. Carotenoids reflect red, orange or yellow light.

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15
Q

where does the light indipendent reaction take place

A

in the stroma of the chloroplast

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16
Q

somtimes the light independant reaction is described as the dark phase . why is that incorrect ?

A

as it does not onlytake place during the dark , it can take place during any part of the day . even though the process uses no llight.

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17
Q

what is an antenna complex/photosystem

A

chlorophylls and carotenoids are grouped in clusters called antenna complex or photosystems located on the thylakoid membrane carotenoids absorb photons of light which then transfer energy to chlorophyll A which are located at reaction centres (near the bottom )

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18
Q

describe the structure of a chlorophyll A molecule

A

A Polar head with a magnesium atom in the centre. This absorbs the light.

A Non polar tail which anchors the chlorophyll molecule into the thylakoid membrane.

Chlorophyll B very similar, but less abundant

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19
Q

what are the primary pigments and what type of colour wavelength do they absorbe

A

hlorophylls - primary pigments:
Chlorophyll a & chlorophyll b absorb light mainly in the red and blue violet regions of the electromagnetic spectrum

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20
Q

what are the accessory pigments and what type of colour wavelength do they absorb

A

Carotenoids – accessory pigments:
carotenes and xanthophylls absorb light from the blue violet region of the spectrum. Absorbing wavelengths of light not absorbed by the chlorophyll and then passing the energy to chlorophyll A molecules.

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21
Q

describe the diffrence between the two photosystems

A

Photosystem I : arranged around a chlorophyll a molecule with an absorption peak of 700nm - called P700

Photosystem II : arranged around a chlorophyll a molecule with an absorption peak of 680nm - called P680

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22
Q

what is the equation for the Rf value

A

Rf value = distance travelled by pigment / distance traveled by the solvent

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23
Q

how does photosynthesis maximise its effeciency

A

by making sure to use multiple diffrent pigments inoder to get a range of wavelengths that are absorbed

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24
Q

what is the importance of the accessesory pigment

A

inorder to cover a broader range of wavelengths

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25
Q

where might you find plants with high level of accesssory pigemtns

A

with areas of low level of light

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26
Q

what is the diffrence between a Absorbtion spectra and a Action spectra

A

Absorbtion spectra :
shows the absorbstion of light at diffrent wavelengths for each pigment over a range of wave lengths
maybe have multiple lines representing diffrent pigments

action spectra :
shows the rate of photosynthesis at diffrent wavelengths of light

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27
Q

what does it mean to get reduced

A

gain electrons
oxi number to decrease
loss of oxygen
gain of hydrogen

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28
Q

what does it mean to get oxidised

A

loss if electrons
oxinumber increases
gain of oxygen
loss of hydrogen

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29
Q

what are co-enzymes

A

Co- enzymes are molecules that aids an enzyme . they transfer a chemical group (like hydrogen) from one molecule to another

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30
Q

what are the two products of the light dependent stage , and what are their roles

A

1) ATP
Light energy is transformed into chemical energy. Electrons are used to make ATP in photophosphorylation. This is then used to drive other biochemical reactions in the light independent stage

2) Reduced NADP
Protons are used to reduce NADP (which acts as a hydrogen carrier). The reduced NADP is used in the light independent reactions

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31
Q

what is the role of reduced NADP

A

it is a hydrogen carrier

NADP transfers hydrogen from LDR to the Calvin cycle. As it accepts the hydrogen to be reduced, the concentration of protons in the stroma becomes lower.

Reduced NADP can be represented by NADPH2 or NADPH + H+ or simply reduced NADP

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32
Q

what are the two ways tha ATP can be synthesized ?

A

1) non-cyclic photophorolation - Involves photosystem 1 and 2 and includes reducing NADP to reduced NADP

2) cyclic Photophosphorilation - photosystem 1 only and no reduced NADP is made.

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33
Q

How do the accessory pigments absorb photons

A

Accessory pigments absorb photons of light, then pass the photons of light down to the Chlorophyll a molecules which are situated in the Reaction Centre at the bottom.

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34
Q

blurb about the light dependant reaction ,

how does it happen also draw a diagram of the light dependant reaction

A

https://www.pinterest.co.uk/pin/565061084499264827/

  1. Light energy (photons) strikes chlorophyll a in PSII exciting its electrons, boosting 2 of them to a higher energy level. These electrons leave the chlorophyll molecule. The chlorophyll molecule has now been ionised. It has been oxidised. This process is know as photoionisation.
  2. The electrons in the high energy state are accepted by a molecule called an electron carrier in the thylakoid membrane. The electron carrier has been reduced.
  3. The electrons lost from chlorophyll in PSII need to be replaced. Light energy splits water into protons, electrons and oxygen (photolysis). The electrons are accepted by the chlorophyll a molecule. This occurs in the thylakoid space (lumen)
  4. Electrons are passed along a series of electron carriers in a series of redox reactions. This electron chain is in the thylakoid membrane. As electrons pass from carrier to carrier electron energy is lost and used to pump protons from the stroma into the thylakoid space to produce ATP by the chemiosmostic theory (explained later)
  5. Electrons enter PS I where light excites them, boosting them to an even higher energy level.
  6. Electrons enter a final electron carrier
  7. Electrons and protons reduce NADP to NADPH2 which pass to the Calvin cycle with the two ATP made.
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35
Q

in what direction are hydrogens pumped in during the light dependant reaction

A

the hydrogen ions move from the stroma into the thylakoid lumen

36
Q

what is it called when chloroplast are ioned by light

A

photoionisation.

37
Q

what is it called when water is split into 1/2 O2 and 2H+ by light during the photosystem 2

A

photolysis

38
Q

why is cyclic phosphorylation used

A

If there is no NADP available then the electrons fall back into the electron transport chain (about half way along) and generate 1 ATP. Electrons can be recycled through PSI until NADP is available.

39
Q

this is a question on cyclic phosporilation :
1) which photosystem is involved ?
2) is reduced NADP produced in the cyclic reaction ?
3) is ATP produced in the cyclic reaction ?
4) is oxygen gas produced in the cyclic reaction
5) why is the reaction described as cyclic

A

1) photosystem 1
2) no
3) yes
4) no
5) because the same electron is used to produced as much atp as the plant requires , best shown from the z-diagram of cyclic phosphorylation

40
Q

what is the definition of chemiosmosis

A

Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An important example is the formation of adenosine triphosphate by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis.

41
Q

describe the stages of chemiosmosis

A

1) As electrons flow along the electron carriers in the thylakoid membrane, they provide energy to pump protons from the stroma into the thylakoid space (lumen).

2) This creates a high concentration of protons in the thylakoid space and low in the stroma

3) The thylakoid membrane can maintain the electrochemical gradient as it is impermeable to protons.

4) The protons will eventually flow back into the stroma through ATP synthase channels proteins.

5) The protein channels form small granules on the membrane surface so are known as stalked granules.

6) The flow of protons cause changes in the structure of the enzyme that catalyse the formation of ATP from ADP and inorganic phosphate.

42
Q

what type of phosphorylation occurs in the light dependent reaction

A

oxidative phosphorilation (normally through a channel / carrier protein)

43
Q

why can the thylakoid membrane maintain the electrochemical gradient

A

as it is impermeable to protons.

44
Q

draw out the calvin benson cycle

and also blurb about the steps

A

https://quizlet.com/gb/853087326/lir-diagram/

  1. Carbon dioxide diffuses into leaf via stomata, dissolving in the water surrounding palisade mesophyll cells.
  2. Carbon dioxide combines with the 5 carbon compound ribulose bisphosphate (RuBP) using the enzyme RUBISCO to form an unstable 6C compound.
  3. Unstable 6C compound immediately breaks down into 2 molecules of glycerate 3-phosphate (GP).
  4. Using one ATP molecule from the light reaction, GP is phosphorylated and then reduced to triose phosphate using the hydrogen from reduced NADP.
  5. Triose phosphate molecules combine in pairs to form hexose sugars.
  6. The majority of the triose phosphate molecules produced are used to regenerate RuBP using ATP from the light dependent reaction to supply energy and phosphate. This allows the cycle to continue.
45
Q

1) where does the light independent stage take place
does it need light

2) how what inorganic compound does it use to make hexose suger

A

1) Occurs in the stroma of the chloroplast
Does not need light

2) CO2

46
Q

what are the three rules for something to be classified as an organic compound

A

has to have carbon

has to have a carbon-hydrogen bond

has to have a carbon-carbon bond

47
Q

what are the three main stages of the calvin bensin cycle and define them

A
  1. Carbon dioxide fixation: CO2 is fixed by the reaction of RuBP with CO2 to produce glycerate 3-phosphate using the enzyme RuBisCO.
  2. Phosphorylation of glycerate 3 phosphate using ATP. Reduction of GP to triose phosphate (using reduced NADP which then becomes oxidised).
  3. Regeneration: 2 Triose Phosphate are needed to regenerate RuBP (ATP required),1C would be left, so 6 turns of Calvin cycle and 6 CO2 are needed to synthesise 1 glucose molecule.
48
Q

what does GP stand for and how many carbon atoms does it have

A

Glycerate - 3 - phosphate

3 carbons

49
Q

what does TP stand for and how many carbon atoms does it have

A

triose phosphate

3 carbons

50
Q

what is regenirated during the calvin bensin cycle

A

RuBP (ribulose biphosphate )

it has 5 carbons

51
Q

what is the enzyme used in kalvin bensin cycle

A

rubisco

could also think of the bit at the end -co as like co enzyme

52
Q

what does the calvin bensin cycle produce

A

hexose suger
lipids
amino acids

53
Q

how much reduced NADP and ATP is used

and between where / when

and what for

A

3 ATP are used all together

2 ATP are used and add a phosphate group to the GP to make it TP ATP —> ADP

1 is used to regenerate RUBP losing its phosphate group
ATP —> ADP

2 NADP is used all toghether

is is used to reduce GP into TP NADPH —> NADP

54
Q

how does light effect TP

A

Decreasing light intensity means less ATP and reduced NADP, so less TP is made since ATP and reduced NADP are needed to make TP from GP.

55
Q

how does light effect GP

A

Decreasing light intensity means produces less ATP and reduced NADP , this causes a build up of GP as there is a lack of ATP and reduced NADP to go to TP

56
Q

how does light effect GP

A

Decreasing light intensity means less ATP and reduced NADP, so less RuBP because RuBP is still being used up to make GP but RuBP is not being regenerated as GP cannot be made into TP, which is needed to make RuBP.

57
Q

how does carbon dioxide concentration effect TP

A

As carbon dioxide increases more RUBP can bind to CO2 which produces more GP and therefore more TP

58
Q

how does carbon dioxide concentration effect GP

A

As carbon dioxide increases GP increases. Because more CO2 is fixed, so more GP is made.

59
Q

how does carbon dioxide concentration effect RUBP

A

As carbon dioxide increases means there is more reactions between RUBP and CO2 , no more RUBP can be made but it is more frequently used

60
Q

how does temperature effect TP

A

As temperature increases transpiration increases and therefore less ATP and reduced NADP is made thererfor less GP is made and therefore less TP

however there is more energy for enzymes

61
Q

how does temperature effect GP

A

As temperature increases GP Increases. But at high temperatures will decrease because the enzyme RuBisCO denatures and less carbon dioxide fixed, so less GP will be made and so less TP is made.

62
Q

how does temperature effect RUBP

A

As temperature increases transpiration increases and therefor less ATP and reduced NADP . the lack of ATP and reduced NADP slows down the calvin bensin cycle therefore less RUBP is being used

but also more energy for enzymes

63
Q

how is nitrogen taken up by a plant and how is it used in a plant

A

Plants take up nitrates from the soil, the nitrogen is then used in the synthesis of amino acids, then proteins by condensation.

64
Q

how are lipids made in plants and what are there uses in a plant

A

Lipids are made of Carbon, hydrogen and oxygen only, the same three elements as carbohydrates but in different proportions. The plant can form its own lipids for waxy cuticles etc.

65
Q

how is glucose made and what is it used for in a plant

A

Glucose formed from TP can be condensed to form starch and the isomer Beta glucose will form cellulose, fructose (another hexose) and sucrose (a disaccharide) can be formed.

66
Q

how is nitrates transported in a plant

A

xylem

67
Q

how are amino acids transported in a plant

A

phloem

68
Q

what is the appearance of a plant with nitrogen deficiency

A

reduced growth of all organs and chlorosis

69
Q

what is chlorosis

A

Chlorosis = yellowing of leaves, as a result of loss of chlorophyll.

70
Q

info card read and recite

A

In the case of magnesium deficiency the symptoms generally start with mottled chlorotic areas developing in the interveinal tissue. The interveinal laminae tissue tends to expand proportionately more than the other leaf tissues, producing a raised puckered surface, with the top of the puckers progressively going from chlorotic to necrotic tissue

71
Q

1) what is the role of magnesium in plants

2) where is it transported

3) what are the signs of deficiency

A

1) Forms part of the Chlorophyll molecule

Found within the hydrophylic head (the hydrophobic tail is a long hydrocarbon molecule that anchors the chlorophyll within the thylakoid membrane)

The head is used for absorbing and transducing the light energy into chemical energy.

Used for activation of ATPase

2) zxylem

3) chlorosis , stunt in growth

The chlorosis shows up in older leaves first, because plant moves Mg+ to newer leaves.

72
Q

what is the law of limiting factors

A

When a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply

73
Q

what are the limiting factors of rate of photosynthesis in a plant

A

Light intensity

Availability of water

Availability of carbon dioxide

Availability of chlorophyll

Temperature

74
Q

how does tempreatur effect photosynthesis rate

A

The light-independent reaction of photosynthesis is controlled by enzymes. Temperature affects enzyme reactions.

As temperature increases, collision frequency between reactant particles and between reactant and enzyme increases. This increases the rate of reaction up to the optimum temperature.

Beyond the optimum temperature however, enzymes begin to be denatured. Their tertiary structure breaks down, changing the shape of the active site so that reactant molecules no longer fit.

75
Q

how does atmospheric carbon dioxide effect photosynthesis rate

A

Carbon dioxide is essential for the photosynthesis process. It is used during the light-independent stage to carboxylate ribulose bisphosphate.

The normal concentration for atmospheric carbon dioxide varies between 0.03 % and 0.04 %.

Plants are adapted to survive in varying concentrations of CO2, but the higher the value, the higher the rate of photosynthesis.

Plants may therefore be able to remove some of the CO2 released by human activity from the air.

76
Q

what is the compensation point

A

wherer the rate of photosynthesis matches the rate of respiration

77
Q

what is it called when :
A series of small reactions controlled by enzymes (like photosynthesis)

A

Metabolic pathway

78
Q

what is :
Phosphorylation

A

adding phosphate to a molecule (ADP – ATP)

79
Q

what is :
Photophosphorylation

A

adding a phosphate group using light

80
Q

what is :
Photolysis

A

Splitting (lysis) of a molecule using light (photo)

81
Q

what is :
Hydrolysis

A

Splitting (lysis) of a molecule using water (hydro)

82
Q

what is :
Decarboxylation

A

The removal of carbon dioxide from a molecule

83
Q

what is :
Dehydrogenation

A

The removal of hydrogen from a molecule

84
Q

what is :
Redox rections

A

Reactions that involve oxidation and reduction (more on this on the next page)

85
Q

how is light level used in agriculture

A

by light levels of spesific wavelength being released from lamps . it increases the production of ATP and reduced NADP in LDR . as more light hits the chlorophyll this causes more excitation

86
Q

how is CO2 used in agriculture

A

green houses controll concentrations of CO2 . this is used to link RUBP which makes GP and therefore TP which is later used for amino acids lipids and sugers. in Light independant reaction

put green houses near a factory then CO2 wont be a limiting factor

87
Q

how is temperature used in agriculture

A

green house (closed enviroment) in which we can controll tempreature .

this increases kenetic energy and therefor the likly probablilty for an enzyme to react is greater , while also frequency increasing

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