5.1 Photosynthesis Flashcards
(93 cards)
1
Q
What do the genes in a chloroplast DNA code for
A
Photosynthetic enzymes
2
Q
What is the name of the chloroplast cytoplasm
A
Stroma
3
Q
What do the thylakoids contain
A
Chlorophyll
4
Q
What is the name of the enzyme we need to know that’s involved in photosynthesis
A
Rubisco
5
Q
What is the chemical GCSE equation for photosynthesis
A
6CO2 + 6H2O -> C6H12O6 + 6O2
6
Q
What is the name of the 2 stages in photosynthesis
A
- Light dependent stage
- Light independent stage
7
Q
Where does the light dependent stage occur
A
In the thylakoid membrane
8
Q
Where do the light independent stage occur
A
In the stroma
9
Q
What are the 2 things that the light dependent stage requires
A
- Light
- Chlorophyll
10
Q
In the light dependent stage what does the photosynthetic pigment absorb
A
Energy
11
Q
What is the reactant for the light dependent stage
A
Water
12
Q
What is the photosynthetic product of the light dependent stage
A
Oxygen
13
Q
During the light dependent stage, how does NADP become reduced
A
By the addition of the hydrogen that is released from the water
14
Q
What is the chemical formula of reduced NADP
A
NADPH2
15
Q
What is the reactant for the light independent stage
A
Carbon dioxide
16
Q
What is the product from the light independent stage/ what is the name of the carbohydrate formed
A
CHO , triose phosphate
17
Q
In terms of hydrogen, what is oxidation
A
Remove of hydrogen
18
Q
In terms of hydrogen, what is reduction
A
The add of hydrogen
19
Q
In the light dependent stage, what is oxidised
A
Water
20
Q
In the light dependent stage, what is reduced
A
NADP
21
Q
In the light independent stage, what is oxidised
A
Carbon dioxide
22
Q
What is the overall equation in the light dependent stage
A
H2O + NADP -> NADPH2 + O2
23
Q
If NADP is removed from the light dependent stage, will oxygen still be produced
A
NO
24
Q
When light energy is absorbed by the chlorophyll, what does this excite
A
2 electrons
25
In the light dependent stage, what happens to the 2 excited electrons
They leave the chlorophyll and pass to an electron acceptor
26
What is the name of the process by which 2 electrons get excited and leave the chlorophyll
Photoionisation of chlorophyll
27
Once the excited electrons leave the chlorophyll what are they passed along
A series of electron carriers
28
What happens to the electrons in the light dependent stage as they pass along a series of electron carriers
They lose energy
29
What is the energy that is released from the electrons as they move along a series of electron carriers used to produce
ATP from ADP and Pi by chemiosmosis
30
What is the name of the process by which the energy that the electrons lose as they move along the series of electron carriers is used toe produced ATP from ADP and Pi
Chemiosmosis
31
What is the name of the process where a water molecule is split
Photolysis
32
What is the equation of photolysis of water
2H2O -> 4H+ + 4e- + O2
33
Where do the electrons that replace those that are lost from the chlorophyll come from
The photolysis of water
34
What is the name of the process where a water molecule splits
Photolysis of water
35
What is the photolysis of water equation
2H2O -> 4H+ + 4e- + O2
36
Where do the electrons that replace those lost from the chlorophyll come from
The photolysis of water
37
What are the protons produced from the photolysis of water used for
They reduce NADP
38
What is the by-product of water photolysis
Oxygen
39
Where do the electrons for reduction of NADP come from
The photoionisation of chlorophyll
40
Where do the protons for the reduction of NADP come from
The photolysis of water
41
In the chemiosmosis theory, what happens to the high energy electrons
They pass along a series of electron carriers
42
In the chemiosmosis theory, what happens to the high energy electrons as they pass along the series of electron carriers
They lose energy
43
In the chemiosmosis theory, what is the energy that is lost from the electrons used for
Used to pump protons, H+
44
In the chemiosmosis theory, where are the protons pumped from and where are they pumped to
Pumped from the stroma into the thylakoid space
45
After the protons are pumped into the thylakoid space in the chemiosmosis theory, what is produced and why
A concentration gradient is produced since the protons accumulate
46
Once a concentration gradient of protons has been established in the chemiosmosis theory, what happens to the protons
They diffuse back into the stroma via ATP synthase.
47
What provides the energy to form ATP from ADP and Pi
ATP synthase which is associated with the channel protein in the thylakoid membrane
48
What does the ATP synthase associated with the channel protein in chemiosmosis essentially act as
A molecular motor
49
How can the reduction of NADP be demostrated experimentally
Using an artificial hydrogen acceptor like DCPIP
50
What is DCPIP
An artificial hydrogen acceptor
51
What is the reaction called when the reduction of NADP is demostrated experimentally using an artificial hydrogen acceptor
Hill Reaction
52
What is the colour of oxidised DCPIP
Blue
53
What is the colour of reduced DCPIP
Colourless
54
What happens to DCPIP when it is added to a suspension of isolated chloroplasts
It'll be reduced under certain conditions
55
In the Hill Reaction, what type of solution is added to all 4 test tubes
Cold, isotonic and buffered solution
56
In the Hill reaction, why does on test tube only contain chloroplasts and the solution but no DCPIP
To act as the colour standard
57
In the Hill reaction, what does the test tube with only the solution and DCPIP act as
The control because it has no chloroplasts inside - so it's evidence that the reduction of DCPIP is down to chloroplasts being present
58
In the Hill reaction, why is one of the test tubes with chloroplasts, solution and DCPIP put in a dark space while the other test tube is put beneath a lamp
The light dependent reaction in the chloroplasts will only occur in the test tube under the lamp and without the light dependent reaction there is no reduction of NADP since no photoionisation nor photolysis of water so no reduction of DCPIP
59
In the Hill reaction, which on the 2 test tubes with chloroplasts, solution and DCPIP inside becomesc the colour of the test tube with only chloroplasts and solution
The test tube that was placed under light e.g. a lamp so the test tube where the light dependent reaction occured so NADP was reduced so DCPIP was also reduced
60
Explain how the chemicals which inhibit the decolourisation of DCPIP could slow the growth of weeds ( 2 marks)
- Less/ no ATP produced
- Less/ no NADPH2 produced
61
Where does the light independent reaction occur
In the stroma
62
What are the 4 requirements for the light independent reaction
- Carbon dioxide
- ATP
- NADPH2
- Rubisco
63
What are the 3 products of the light independent reaction
- Triose phosphate
- ADP and Pi
- NADP
64
What is the name of the cycle in the light independent reaction
Calvin cycle
65
How many carbons are in RuBP
5 carbons
66
What is added to the calvin cycle that reacts with RuBP
Carbon dioxide
67
What does RuBP and CO2 produce in the calvin cycle
GP (Glycerate-3-phosphate)
68
How many G-3-P molecules are produced from one RuBP molecule
2
69
What is the name of the enzyme in the calvin cycle
Rubisco
70
What type of reaction converts G-3-P into Triose phosphate
Reduction
71
When G-3-P is reduced into triose phosphate, what is oxidised
NADPH2 to NADP
72
When G-3-P is reduced into triose phosphate, what is needed and where is this provided from
Energy is needed from ATP being hydrolysed into ADP and Pi
73
What is needed to convert triose phosphate into RuBP
ATP
74
Why is ATP needed to convert triose phosphate into RuBP
Since the Pi phosphorylates the molecule - essentially add another phosphate group to the molecule to produce RuBP
75
What are the 3 molecules that the triose phosphate that left the cycle can be converted into
- Glucose
- Amino acids
- Glycerol and fatty acids
76
If 6 RuBP molecules are used in the cycle along with 6CO2, how many G-3-P are made
12
77
If 12 G-3-P molecules are produced, how many triose phosphate can be formed after the reduction
12
78
Of the 12 triose phosphate molecules made in the calvin cycle how many remain in the cycle
10 triose phosphates and get converts into RuBP
79
Of the 12 triose phosphate molecules produced, how many leave the cycle to be converted into biological molecules
2
80
What would happen to the concentration of G-3-P if the plant was placed in the dark
The concentration would increase but eventually flatten out
81
Why would the concentration of G-3-P increase if the plant was placed in the dark
Since RuBP and CO2 will still be able to form G-3-P however without the products from the light dependent reaction G-3-P cannot be reduced into triose phosphate so the concentration of G-3-P builds up
82
What happens to the concentration of RuBP if the plant was placed in the dark
The concentration will fall until it eventually reaches zero
83
Why does the RuBP concentration fall when the plant is placed in the dark
Since the RuBP is being used to make G-3-P and less RuBP is being made compared to what is being used to make other molecules since there is less triose phosphate so eventually the triose phosphate will run out so no more RuBP will be synthesised hence why the concentration will drop
84
State one measurement that could be taken to determine the rate of photosynthesis
Change in pH or the volume of oxygen produced
85
What is the explanation that explains why the factor on the x-axis is the limiting factor initally
As the x-axis factor increases so does the rate of photosynthesis and then when the graph plateus another factor becomes the limiting factor
86
Why can the rate of photosynthesis increase when carbon dioxide is leaving the plant instead of being absorbed
Since carbon dioxide is produced via aerobic respiration
87
When the temperature increases, why does the rate of photosynthesis increase
Since the kinetic energy increases so the enzymes involved in photosynthesis gain kinetic energy, so more enzyme-substrate complexes form
88
After the optimum temperature and the temperature still rises why does the rate of photosynthesis decreases
The enzymes for photosynthesis denature
89
Describe the role of thylakoid membranes in the synthesis of ATP
- The thylakoid membranes provide a large surface area for the attachment of chlorophyll electron carriers, and ATP synthase, maintaining ATP production
- The thylakoid membranes contain electron carrier that transfer electrons through a series of redox reactions, releaing energy
- Energy from the electron transfer chain is used to pump protons into the thylakoid lumen, /creating a proton gradient across the membrane
- Protons diffuse back into the stroma through ATP synthase, driving the phosphorylation of ADP to ATP
90
Explain the importance of the formation of ATP and NADH2 in the LDR
- ATP is used for the synthesis of carbohydrates in the Calvin cycle
- NADPH2 provides hydrogen for the reduction of G-3-P to triose phosphate in the Calvin cycle
- ATP provides the energy for this redox rea/ction and the energy needed to regenerate RuBP
91
Describe the light-independent reaction of photosynthesis (6 marks)
1. Carbon dioxide
combines/reacts with ribulose
bisphosphate/RuBP;
2. Produces two glycerate (3-
)phosphate/GP using
(enzyme) Rubisco;
3. GP reduced to triose
phosphate;
4. Using reduced NADP;
5. Using energy from ATP;
6. Triose phosphate converted to
glucose/hexose/RuBP/ribulose
bisphosphate/named organic
substance;
92
Describe how the products of the light-dependent reaction are used in the light-independent reaction to produce triose phosphate (3 marks)
- ATP and reduced NADP
- ATP provides energy
- GP reduced to triose phosphate
93
Atrazine binds to proteins in the electron transfer chain in chloroplasts of weeds, reducing the transfer of electrons down the chain. Explain how this reduces the rate of photosynthesis in weeds (4 marks)
- Reduced transfer of protons across thylakoid membrane
- So less ATP produced
- So less reduced NADP produced
- So light-independent reaction slows/ stops
OR
Less reduction of GP to triose phosphate
