Photosynthesis Flashcards
1
Q
What type of process is photosynthesis?
A
Physiochemical process Uphill process Redox reaction Endogonic Primary source of food is photosynthesis
2
Q
What did variegated leaf exp prove?
A
starch is needed for photosynthesis
3
Q
black paper experiment
A
light and chlorophyll are essential for photosynthesis
4
Q
Moll’s half leaf experiment
A
CO2 is essential for photosynthesis
5
Q
Father of plant physiology
A
stephan hales
6
Q
Which was priestly’s experiment?
A
Mice and candle
7
Q
Who modified Priestly’s experiment and proved what?
A
Jan Ingenhousz used a similar setup used by Priestly but by placing once in dark and once in light.
Proof: only green parts of the plant release oxygen in the presence of sunlight
8
Q
Von sach
A
Glucose- reactive and water soluble (Formation)
Sucrose- non reactive and water soluble (Transport)
Starch- non reactive and insoluble (Storage)
9
Q
Why is glucose reactive?
A
Due to presence of free aldehydic group
10
Q
Engelmann
A
First action spectrum of photosynthesis using prism and cladophora algae
max photosynthesis in red and blue
min photosynthesis in green
11
Q
How are leaf pigments separated?
A
Leaf Pigments are separated by paper chromatography
12
Q
Colour of the lead pigments
A
- Chl a - Bright green or bright blue green
- Chl b- Yellow green
- Xanthophyll- Yellow
- Carotenoid- Yellow orange
13
Q
The green colour pigment in green bacteria-
A
Bacterioviridin or Chlorobium chlorophyll
14
Q
Purple colour pigment in purple bacteria
A
Bacteriochlorophyll or Bacteriopurpurin
15
Q
Is chlorophyll soluble or insoluble?
A
Insoluble in water and soluble in organic solvents
16
Q
Where does the chlorophyll occur in plants?
A
In the chloroplasts
17
Q
Chlorophyll a
A
- C55H72O5N4Mg
- Universal photosynthetic pigment
- Primary photosynthetic pigment
- Most abundant photosynthetic pigment
18
Q
Who is the precursor of Protochlorophyll?
A
Glycine + Succinyl CoA
19
Q
Precursor of chlorophyll
A
Protochlorophyll (inactive form)
20
Q
How is precursor of protochlorophyll activated?
A
Protochlorophyll is activates by light and 2H
21
Q
Three minerals essential for chlorophyll synthesis
A
Mg
Fe
N
(Mg and N are structural constituents)
22
Q
Structure of Chl a
A
- Tadpole like structure
- It consist of a Pophyrin head and a phytol tail
- Head: Hydrophilic, acidic, tetrapyrol structure, Mg is held by 2 covalent and 2 coordinate bonds
- Tail: Hydrophobic, alcoholic, embedded in lipid bilayer of thylakoid membrane
23
Q
Chl b
A
Similar structure to Chl-a but -CHO is present in place of -CH3 in 3rd position of II pyrole ring
C55H70O6N4Mg
24
Q
Chlorophyll c
A
Lacks a phytol tail
25
Where are carotenoid present
carotenoids are present in the chromoplast and occur along with chlorophyll inside chloroplast
26
Are carotenoids soluble or insoluble?
Carotenoids are insoluble in water
27
Chemical nature of caratenoids
Terpenes and considered most stable pigments(because they are HC with conjugate double bonds). Light is not necessary for their synthesis.
28
Two types of caratenoids
Carotenes and Xanthophyll
29
Carotenes.
1. Emp formula is C40H56
2. alpha beta gamma carotenes
3. Beta carotene is the most common in plants and responsible for color of carrots
4. Red colour of chilli and tomato is due to Lycopene
30
Xanthophyll
1. Yellow in color containing derivatives of carotene
2. Lutein: C40H56O2
3. Lutein cause autumn colouration of leaf
4. Fucoxanthin (Brown Algae)
5. Diatoxanthin (Dinoflagellates)
31
Function of Caratenoids
1. They protect the chlorophyll from photooxidation by absorbing excess light radiation.
2. Known as SHIELD PIGMENTS as it prevents harmful effect of nascent oxygen by converting it into molecular oxygen.
3. Accessory pigments and make photosynthesis more efficient by absorbing different wavelengths of light.
4. Beta carotene acts as a precursor of Vitamin A.
5. They help in Entomophilly and Zoophilly
32
Are phycobillin soluble or insoluble?
Phycobillins are soluble in hot water
33
Structure of phycobillin
Open tetrapyrole structure because Mg is absent and phytol tail is also absent
34
where are phycobillin found
Found in vacuoles of plant cells
35
Types of phycobillin
Phycocyanin (blue)
Phycoerythrin (red)
Allophycocyanin (light blue)
36
Maximum absorption by Chl a
Blue light
37
Maximum absorption of blue light
Chlorophyll b
38
Maximum absorption of red light
Chlorophyll A
39
Maximum photosynthesis takes place in
Blue light
40
Max efficiency of photosynthesis
Red light
41
Determine the wavelength which chlorophyll a shows the maximum absorption
Wavelength= 450nm= Blue
42
What kind of PS occurs in the granal thylakoids?
Cyclic and non cyclic (PS I and PS II)
43
What kind of cycle takes place in strongly thylakoids?
Cyclic (PS I)
44
Non cyclic photophosphorylation is absent in stromal thylakoids because-
1. PS II is absent
| 2. Absence of NADP dedicated enzyme
45
OEC
* Oxygen reducing complex
* only in PS II
* Mn+2, Ca+2 and Cl- associated with OEC (reqd for photolysis of water)
* location in inner membrane’s inner part
46
First electron acceptor of non-cyclic photophosphorylation
Phaeophytin
• chlorophyll a - Mg + H20
47
In photolysis of one water molecule how many oxygen molecule or atom is released?
1/2 oxygen
48
How many electron in the ETS is released by photolysis of water
2e
49
How many H accumulated in the linen of granal thylakoid
4H
• 2H by water splitting
• 2H by proton pump
50
How many NADPH + H+ is synthesised by photolysis of water molecule
1 NADPH2
51
How many quanta of light reqd to spilt one molecule of water?
4 quanta of light is required
52
How many H+ to synthesise one ATP?
3H+ ——> 1 ATP
53
Proton novice force
This force pushes proton outside via proton channel
1. Proton gradient
2. Electron potential
3. pH gradient
54
Condition for non cyclic photophosphorylation
1. High availability of NADP
| 2. High light intensity or low wavelength radiation
55
Condition for cyclic photophosphorylation
1. Low availability of NADP
| 2. Low light intensity (>680) or high wavelength radiation
56
What is redox potential?
Redox potential is Electron withdrawing power
57
other names of dark reaction
Biosynthetic phase
Blackman’s reaction
CO2 reduction
58
where does the dark reaction take place?
dark reaction takes place in the storms
59
Why is RuBisco active specifically during the day?
Because it needs Light and Mg
60
Most abundant enzyme or protein present in nature?
RuBisCo
61
How much % of protein present in nature is RuBisCo?
70%
62
How much % of protein present in nature is chloroplast?
16%
63
On what was the Calvin cycle studied?
Chlorella (green algae) by using radioisotrophy C-14
64
Which step is the most crucial step in the Calvin Cycle or C3 cycle?
Carboxylation step
65
How many ATP is used in the Calvin cycle?
3ATP
i) 2ATP in reduction step
ii) 1ATP in regeneration
66
How many NADPH+H+ is required in the calvin cycle?
2NADPH2 required
i) 2 in reduction
ii) 0 in regeneration
67
How many ATP and NAPH2 is required in carboxylation step?
No ATP and NADPH2 is required in carboxylation step
68
What is the equivalent of NADPH2 and ATP
1NADPH2= 3ATP
69
Ratio of rate of photosynthesis and rate of respiration during the daytime
10:1
70
favourable condition for photosynthesis
1. High light intensity
| 2. High temperature
71
Why is photorespiration a wasteful process?
25% of CO2 lost
| No synthesis of ATP or NADPH2 or glucose hence it is a wasteful process
72
Primary CO2 acceptor in C4 cycle
PEP which is fixated by the enzyme PEPcase and converts it to OAA
73
How is PEP regenerated?
Pyruvic acid(3C) — [ATP->AMP//PPDK] ——> PEP
• 2ATP used
74
PPDK
Pyruvate Phosphate Dikinase is a sensitive enzyme and DOES NOT work in LOW TEMP
75
Total ATP required in the C4cycle
5ATP
• 3ATP in Calvin cycle
• 2ATP in regeneration of PEP from pyruvic acid
76
Total NADPH2 required in the C4 cycle
2NAPDH2 (in calvin cycle)
77
Number of ATP required for synthesis of glucose in C4 cycle
30ATP
* 18ATP in C3
* 12ATP in regeneration of PEP
78
How many ATP equivalent are consumed in Calvin cycle for synthesis of 1mole of glucose?
54ATP
* 18ATP
* 2NADPH2 = 36ATP
79
Special adaptations of C4 plants
1. Adapted to high light intensity due to negligible photorespiration
2. Adapted to high temp because PPDK works best in high temp
3. Adapted to water stress due to partial closure of stomata hence reducing water loss. PEPcase performs best photosynthesis even in low concentration of CO2
4. C4 pants fixes double CO2 with half amount of water loss as compared to C3 plants
80
Name some plants with follows C3 pathway
Rice and Wheat
81
Name some plants which follow C4 pathway
1500species
19families
= 900 monocots
• maize
• sugarcane
• sorghum
82
who follows CAM pathway?
Crussulacean family —> Succulent xerophytes —> scotoactive stomata (open at night only)
83
Number of ATP required for fixation of 1CO2 molecule in CAM plants
5ATP
•3 in C3
•2 in regeneration of PEP
84
number of NADPH2 required in CAM plants
2 in the calvin cycle
85
ATP and NADPH2 requirement to synthesise glucose in CAM plants
30ATP
• 18 in C3, 12 in regeneration of pep
2NADPH2
86
Low light intensity (C3 or C4?)
C3
87
High light intensity (C3 or C4?)
C4
88
low temperature (C3 or C4?)
C3
89
High temperature (C3 or C4?)
C4
90
Water stress (C3 or C4?)
C4
91
Low CO2 / high O2
| C3 or C4?
C4
92
High CO2 / low O2
| C3 or C4?
C3
93
In non cyclic photophosphorylation initial capturing of electron is by?
PS-II
94
in non cyclic photophosphorylation capturing of proton by?
NADP+
95
in non cyclic photophosphorylation ultimate donor of electron
H2O
96
plants capture which wavelengths of light
4000 to 7000A
97
light compensation point
intensity of light at which
rate of photosynthesis(food production)= rate of respiration(food consumption)
NPP is zero at this point and no gaseous exchange between plant and atmosphere
98
major limiting factor for photosynthesis
carbon dioxide
99
Saturation point of C4 and C3 plant respectively
C4 - 360 ppm
C3 - 450 ppm
therefore CO2 is limiting factor for C3
100
CO2 compensation point for C4 and C3 respectively
C4: 0-10 ppm
C3: 25-100 ppm
101
Optimum temperature for C4 and C3
C4 30-40C
C3 20-25C
102
Tropical plants have higher temperature optimum than temperate climate plants
..
103
Oxidation of ____ leads to the formation of ABA
Carotene
104
Example of increase in productivity due to CO2. fertilisation
Tomato and Spinach
105
DCMU and PAN are used as weedicide or herbicides. What do they block? (non cyclic inhibitor)
DCMU blocks the flow of electron from P680 to plastoquinone
106
Name a cyclic inhibitor
Diquat, Paraquat viologen dyes block electron flow from P700 to Fd
