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A-Level Biology > Photosynthesis and etc > Flashcards

Photosynthesis and etc Flashcards

1
Q

What is the photosynthesis equation?

A

Carbon dioxide + water —-> glucose + oxygen

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2
Q

What is the photosynthesis symbol equation?

A

6CO2 + 6H2O —-> C6H12O6 + 6O2

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3
Q

What is the importance of photosynthesis?

A

Provides energy all living things require
Produces O2
Chlorophyll converts it to chemical energy
Plants use molecules to produce ATP for respiration
Non-photosynthetic organisms feed on molecules produced by plants

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4
Q

What are the features of a plant cell?

A 
Amyloplast
SER
RER
Nucleus
Ribosomes
Cell wall
Golgi apparatus 
Chloroplast
Vacuole
Cell membrane
Mitochondria
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5
Q

What makes leaves good at photosynthesis?

A 
Large SA
Thin
Transparent cuticle 
Palisade cells long, thin + tightly packed
Many stomata 
Air spaces
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6
Q

Why is it it good that leaves have a large SA?

A

Absorb max light

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7
Q

Why is it it good that leaves are thin?

A

Efficient gas exchange

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8
Q

Why is it it good that leaves have a transparent cuticle?

A

Allows light to upper mesophyll

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9
Q

Why is it it good that leaves have palisade cells that are long,thin + tightly packed?

A

Max light absorption

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10
Q

Why is it it good that leaves have many stomatas?

A

Efficient gas exchange + short diffusion distance

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11
Q

Why is it it good that leaves have air spaces?

A

Rapid gas exchange

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12
Q

What structures are present in a chloroplast?

A 
Outer membrane
Inner membrane
Thykaloid sticks 
Stroma
Grana 
Intergranal lamellae
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13
Q

What do thykaloid discs contain?

A

Chlorophyll

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14
Q

What is grana?

A

Stacks of thykaloid sticks

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15
Q

What is the stroma?

A

Fluid-filled matrix around grana

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16
Q

Where does the LIDR take place?

A

Stroma

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17
Q

Where can starch grains be found?

A

Stroma

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18
Q

What do some thykaloid sticks have?

A

Tube shaped extensions

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19
Q

What does the tube shaped extensions connect?

A

Grana

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20
Q

What is it called when the tube shaped extensions join the grana?

A

Intergranal lamellae

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21
Q

What is the function of granal membranes?

A

Large SA for chlorophyll, electron carriers + enzymes

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22
Q

What is the function of the network of proteins in grana holding chlorophyll in specific way?

A

Allows for max light absorption

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23
Q

What is the function of the fluid in the stroma containing enzymes?

A

Needed for LDR

Allows to maintain optimum enzyme conc

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24
Q

What is the function of chloroplasts containing DNA + ribosomes?

A

Can quickly + easily manufacture proteins needed for photosynthesis

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25
Q

What is the function of granal membranes having ATP synthase channels?

A

Catalyse production of ATP

Selectively permeable

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26
Q

What is the function of stroma surrounding grana?

A

Products from LDR easily diffuse into stroma for LIDR

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27
Q

What is the law of limiting factors?

A

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

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28
Q

What factors affect photosynthesis?

A 
Light intensity
Availability of H2O
Temperature
Availability of chlorophyll
Availability of CO2
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29
Q

What is the compensation point?

A

When the rate of photosynthesis = rate of respiration

30
Q

What does the graph look like for CO2 conc against rate of photosynthesis?

A

Increases then plateaus

31
Q

What does the graph look like for chlorophyll against rate of photosynthesis?

A

Increases then plateaus

32
Q

What does the graph look like for temperature against rate of photosynthesis?

A

Increases the decreases

Upside down “U”

33
Q

Why is the temperature graph different?

A

Increases till optimum
More KE so more successful collisions
Too hot so breaks H bonds so active site denatures

34
Q

What are the three main stages in photosynthesis?

A

Capturing of light energy
LDR
LIDR

35
Q

What does chlorophyll A absorb?

A

Mainly red-orange + blue-violet part of visible light spectrum

36
Q

Describe the first step of LDR

Making ATP

A

Photon of light absorbed = boosts energy level of pair of chlorophyll electrons
Excited electrons leave chlorophyll molecule
Chlorophyll molecule oxidised
ETC gains electrons = photoionsiation

37
Q

Describe 2nd step of LDR

ETC and Photosystems

A 
Excited electrons taken up ETC
Move along ETC from PS2
Series of redox reactions
Each carrier slightly lower energy than previous 
So electrons lose energy at each stage
38
Q

Why do the electrons move?

A

Each carrier has slightly higher affinity for electrons than last
This draws electrons along chain to PS1

39
Q

What are photosystems ?

A

Functional and structural proteins in photosynthesis

40
Q

What do photosystems do?

A

Absorb light + transfer energy and electrons

41
Q

Where are photosystems found?

A

Thykaloid membrane

42
Q

What happens to the energy that is lost?

A

Used to synthesise ATP in photophosphorylation

43
Q

Why do excited electrons pass through 2 photosystems?

A

Further absorbed light energy = increases energy of electrons
Makes energy sufficient for reduction of NADP to NADPH

44
Q

Describe the 2nd step 2.0 of LDR

NADP+

A

NADP final acceptor in ETC so becomes reduced
Reduced to NADPH
NADPH stores electrons + protons till they are transferred to LIDR

45
Q

What is NADP+?

A

Coenzyme that accepts protons + electrons

46
Q

Describe the 3rd step of LDR

Photolysis of water

A

H2O split from light energy absorbed by chlorophyll A
When absorbs light chlorophyll oxidised
Electrons produced from photolysis of water used to reduce chlorophyll

47
Q

What is the equation for photolysis of water?

A

2H2O —-> O2 + 4H+ + 4e-

48
Q

Why are protons very important in LDR?

A

Taken up by NADP = final acceptor

Vital for LDR

49
Q

Why does LDR have 2 photosystems?

A

So electrons have enough energy to be picked up by NADP+ (coenzyme)

50
Q

What is chemiosmosis?

A

The process of electrons flowing down the electron transport chain creating a proton gradient across the membrane to drive ATP synthesis

51
Q

Where does the LDR

A

Thykaloid sticks

52
Q

What is the LIDR called?

A

Calvin Cycle

53
Q

What products of LDR are needed for LIDR?

A

NADPH - used to form simple sugar

ATP - hydrolysis of ATP provides energy

54
Q

What are the three stages of LIDR?

A

Carbon fixation
Reduction
Regeneration

55
Q

Brief description of carbon fixation stage (1)

A

CO2 combined with RuBP to make 2x GP

56
Q

What is RuBP?

A

Ribulose bisphosphate

57
Q

What is GP?

A

Glycerate 3-phosphate

58
Q

Describe carbon fixation stage (1) in LIDR

A 
CO2 diffuses into stroma through stomata
Reacts with 5C RuBP
Catalysed by rubisco
Forms unstable 6C compound
Immediately broken down into 2x GP
59
Q

What is rubisco?

A

Ribulose bisphosphate carboxylase

60
Q

Brief description of reduction stage (2)

A

ATP and NADPH used to reduce GP to TP

61
Q

What is TP?

A

Triose phosphate

62
Q

Describe reduction stage (2) in LIDR

A

NADPH (from LDR) reduces 3C GP into 2x 3C TP using ATP (from LDR)
NADP reformed + returned to LDR

63
Q

Brief description of regeneration stage (3)

A

RuBP regenerated

64
Q

Describe of regeneration stage (3) in LIDR

A

TP has 2 uses:
5/6 - regenerates RuBP using ATP (from LDR)
1/6 - forms organic substance

65
Q

How many times does the Calvin Cycle need to turn to produce one glucose molecule?

66
Q

How many ATPs and NADPHs does the Calvin Cycle need to make one glucose molecule?

A

18 ATP

12 NADPH

67
Q

Describe what happens in the chemiosmotic theory?

A

Proton pumps produces H+ from stroma into thykaloid membrane
Active transport
H+ pass through chemiosmotic channel to stroma
Diffusion
Produces ATP
Catalyses combo of ADP + Pi as they pass through

68
Q

Where is the energy needed for active transport taken from in the chemiosmotic theory?

A

Energy from excited electrons that pass along ETC

Produces ATP

69
Q

What happens as H+ pass through chemiosmotic channel?

A

Change the structure of the enzyme

70
Q

What type of protein in the proton pump in the chemiosmotic theory?

A

Intrinsic protein

A-Level Biology (21 decks)

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