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Biology 2 - Chapter 7 > Photosynthesis > Flashcards

Photosynthesis Flashcards

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1
Q

What is a consumer?

A

Living organism that obtains its nutrients by feeding on other organisms

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2
Q

Decomposer?

A

Fungi/bacteria that feed on dead organic matter

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3
Q

Symbol equation for photosynthesis?

A

6CO2 + 6H2O + light energy = C6H12O6 + 6O2

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4
Q

Word equation for photosynthesis?

A

Carbon dioxide + water + light energy = glucose + oxygen

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5
Q

What does organic mean?

A

Related to/derived from living matter

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6
Q

Describe brief definition of photosynthesis?

A

Light energy is converted into chemical energy in organic molecules (inorganic molecules water/CO2 are used and O2 is produced)

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7
Q

Why is photosynthesis the most vital process on earth?

A

Forms the basis of food chains - provides the energy consumers/decomposers need

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8
Q

Difference between photosynthesis and respiration?

A

Photosynthesis uses CO2 and releases O2, respiration uses O2 and releases CO2

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9
Q

What is important about a chloroplast?

A

Site of photosynthesis

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10
Q

What other organelles are chloroplasts similar to?

A

Mitochondria - both thought to of evolved from prokaryotes originally

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11
Q

Size of chloroplasts?

A

2-10 micro meters

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12
Q

What is endosymbiosis?

A

The process where photosynthesis evolved in prokaryotes and over time were taken into eukaryote cells

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13
Q

What evidence is there for endosymbiosis and chloroplasts evolving from mitochondria?

A

Chloroplasts are only produced from division of other chloroplasts (different process from plant division), chloroplasts have their own genome of circular DNA and own ribosomes

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14
Q

What is special about the chloroplast membrane?

A

Double membrane = chloroplast envelope

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15
Q

What does the outer membrane of chloroplasts do?

A

Allows small ions/molecules to pass into chloroplast

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16
Q

What does the inner membrane do?

A

Controls molecules entering and leaving the chloroplast (between storm and cystol)

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17
Q

What does inner membrane rely on?

A

Transport proteins

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18
Q

What is a grana?

A

A stack of thylakoids (discs)

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19
Q

What connects grana to one another?

A

Intergranal lamella

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20
Q

What is the chloroplast membrane?

A

Both the outer and inner membrane

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21
Q

What ribosomes do chloroplast contain?

A

70s ribosomes

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22
Q

What is a photosystem?

A

A funnel shaped collection of accessory pigments with a reaction centre (containing a complex of proteins and chlorophyll molecules) embedded in the thylakoid membrane)

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23
Q

What is the primary pigment in a photosystem?

A

Chlorophyll A

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24
Q

What actually are thylakoids?

A

A third internal system of membranes folded into interconnected plates = thylakoids/lamellae

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25
Q

Where does the light-dependent stage happen?

A

On the thylakoid membranes of the grana

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26
Q

Where and how is light trapped?

A

Trapped by the reaction centre, in the grana

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27
Q

Where are all the pigments needed for the LDS kept?

A

In the reaction centers (in photosystems)

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28
Q

What is the stroma?

A

The gel like medium inside of chloroplasts, carries starch/oil grains swell as enzymes, DNA loops and small ribosomes

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29
Q

What happens in the stroma?

A

The light-independent stage

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30
Q

Adaption of the stroma?

A

Carries enzymes to catalyse LIS, also surrounds grana so transfers products from LDS quickly

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31
Q

Adaption of grana?

A

The stacks have large SA to allow many photosystems = increase max light absorbance and lots of electron carriers & ATP synthase enzymes

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32
Q

Adaption of inner membrane?

A

Has transport proteins to control the chemicals moving between stroma and cytoplasm

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33
Q

Adaption of DNA?

A

Chloroplast DNA codes for some of the proteins/enzymes needed for photosynthesis

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34
Q

What is a light harvesting complex?

A

A photosystem, primary and accessory pigments (in place by proteins), arranged in a funnel shape structure

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35
Q

Where are the photosystems found?

A

Around reaction centres

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36
Q

What do the pigments in the photosystems do?

A

Absorb the light of certain wavelengths, each pigment has specific ranges of wavelengths that its absorbs and the others therefore are reflected

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37
Q

What do the reflected colour of wavelengths do?

A

Produce the visual colour of leaves

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38
Q

What is the main pigment in photosystems?

A

Chlorophyll - a mixture of chlorophyll a and b

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39
Q

What is the primary pigment?

A

Chlorophyll A - found at the reaction centre of a photosystem

40
Q

Is chlorophyll b a primary pigment?

A

No, its an accessory pigment

41
Q

What is the structure of chlorophyll?

A

Have long hydrocarbon chain and a porphyrin group (containing magnesium in the center)

42
Q

What do the light harvesting complexes contain?

A

Chlorophyll a and b, protein molecules, and accessory pigments: carotenes, xanthopylls

43
Q

What happens at the primary reaction centre?

A

The photosystem absorbs light energy, it passes to the reaction centre at the base of the photosystem

44
Q

What are the two types of reaction centre?

A

Photosystem 1 and photosystem 2

45
Q

What is photosystem 1 also known as?

A

P700

46
Q

What is photosystem 2 also known as?

A

P680

47
Q

What does the p700 and p680 indicate about the photosystem?

A

Shows the chlorophyll a molecule maximum absorption of light in the red region of the spectrum (e.g. ps1 has max red absorption of 700 nm)

48
Q

Where is energy sent to in photosystems?

A

Down the funnel into the reaction centre

49
Q

What happens to electrons in the reaction centre?

A

The excited electrons are released and replaced by low energy electrons

50
Q

What do the accessory pigments consist of?

A

Chlorophyll b and carotenoids

51
Q

What does chloroplast b do?

A

Absorb light around 500-640nm and reflects blue green light

52
Q

What are the two main carotenoid pigments?

A

Carotene and xanthophyll

53
Q

What is the role of the accessory pigments?

A

Harvesting light at certain wavelengths and passing it to chlorophyll a

54
Q

Do accessory pigments have a direct role in the light dependent stage?

A

No, their only role is light harvesting

55
Q

What can be used in an experiment to separate photosynthetic pigments?

A

Thin-layer chromatography (using thin layer of adsorbent material spread on top of a thin glass/metal/plastic sheet)

56
Q

How does the thin layer chromatography experiment work?

A

Solvent is used to dissolve pigments, pencil line drawn just above level of solvent, sample of chloroplast extract is spotted onto the paper int he middle of the pencil line, dry then re spot and repeat

57
Q

Where is photosystem 1?

A

On the outer surfaces of the grana and the intergranal lamellae

58
Q

Where is photosystem 2?

A

On the inner membranes of the granola stack

59
Q

What happens first in the light-dependent stage?

A

Absorption of light by pigments in the light-harvesting complexes of photosystems 1 and 2

60
Q

What happens to the light once its harvested?

A

Converted into chemical energy

61
Q

What is the chemical energy used for (converted from light energy)?

A

Splitting of water - releasing H+ ions and O2 as waste gas

62
Q

Why is it essential for water to be split?

A

So that Hydrogen ions are released which can form ATP and reduced NADP

63
Q

What happens when light first hits photosystem 2?

A

Photon of light hits chlorophyll and causes it to vibrate, eventually vibrating electron until it becomes free from chlorophyll

64
Q

What happens after electron has been excited in photosystem 2?

A

Electron moves up to higher electron energy state, passes down electron carrier change, loosing energy as it moves

65
Q

What two ways can electrons go once released energy and leaving chlorophyll molecule?

A

Either return to P2 or accepted by an electron carrier in thylakoid membrane

66
Q

What happens to the electron when leaving an electron carrier?

A

The electron is oxidised (loses electron) and the electron carrier is reduced (gains electron)

67
Q

Why is the energy released by electrons - leaving the electron carriers - essential?

A

This energy is used to actively move protons (hydrogen ions) from the stroma into the thylakoid space

68
Q

What energy state are electrons in when they reach P1?

A

Low, light absorption by P1 re-energises the electrons - so that their energy level is raised and they can leave P1 and be accepted by an electron carrier

69
Q

Where to electrons go after P1?

A

Move to coenzyme NADP - accepting 2 electrons at a time as well at 2 protons from the stroma

70
Q

What does the co-enzyme NADP reductase do?

A

Catalyses reduction of NADP

71
Q

How do protons move from the thylakoid space into the stroma?

A

Down their electrochemical gradient, passing through ATP synthase (protons always being pumped into thylakoid space = high conc but low PH

72
Q

What is chemiosmosis?

A

Production of ATP using flow of protons through ATP synthase enzymes (across thylakoid membranes)

73
Q

What is photolysis?

A

Splitting of a water molecule by the reaction centre in P2 (only occurs in presence of light)

74
Q

What is the non-cyclic pathway?

A

Where electrons move from P2 to P1 and to NADP

75
Q

Why is photolysis essential?

A

Water is the source of the electrons which will enter P2 and the protons for non-cyclic photophosphorylation, as well as the accumulated protons in thylakoid space

76
Q

What is photophosphorylation?

A

Forming ATP using light energy (either cyclic or non-cyclic)

77
Q

What happens in non-cyclic photophosphorylation?

A

Flow of electrons goes to P2, P1, along carrier chain, passed then to NADP - reduced NADP is produced and ATP is formed by chemiosmosis

78
Q

What is different about Cyclic and non cyclic photophosphorylation?

A

Cyclic traps more light energy but does not reduce NADP

79
Q

OIL RIG?

A

Oxidation is loss

Reduction is gain (of electrons)

80
Q

What happens in cyclic photophosphorylation?

A

Electrons pass along a carrier chain still, only enter P1 and then return to their original chlorophyll molecule after passing through electron carriers - water isn’t split and NADP is not reduced

81
Q

What is the electron donor in non-cyclic?

A

Water

82
Q

What is the electron donor in cyclic?

A

P700 in P1

83
Q

What is the final electron acceptor in non-cyclic?

A

NADP

84
Q

What is the final electron acceptor in cyclic?

A

P700 in P1

85
Q

What are the products of cyclic?

A

ATP

86
Q

What are the products of non-cyclic?

A

ATP, reduced NADP and O2

87
Q

Where does the light independent stage occur?

A

In the stroma of chloroplasts

88
Q

Does the light independent stage need light energy?

A

It doesn’t directly use light energy, but it uses the products of the light dependent stage (which used light energy) - can work without light until the light dependent products run out

89
Q

What is the Calvin cycle?

A

The light-independent stage of photosynthesis

90
Q

How does the Calvin cycle begin?

A

Carbon is supplied through CO2 entering the stomatal pores

91
Q

How does carbon diffuse into the chloroplasts?

A

Dissolves in water and diffuses into mesophyll cells and then the chloroplast in those cells

92
Q

What happens after carbon has entered the chloroplasts?

A

The enzyme Rubisco combines RuBP (5C) with CO2 - making a 6 carbon molecule

93
Q

What happens to the 6 carbon molecule?

A

It is unstable so breaks down into two 3 carbon molecules of GP

94
Q

What is carboxylation?

A

When carbon dioxide has become fixed and GP has formed (from the C6 splitting in two)

95
Q

What happens to the two GP molecules in the kelvin cycle?

A

They are reduced by addition of hydrogen - reduced NADP (from light dependent stage) becomes NADP and ATP (from LDS) is converted into ADP - releasing energy and a phosphate

Biology 2 - Chapter 7 (1 decks)

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