Photosynthesis Flashcards
(263 cards)
1
Q
Photosynthesis is a _____ process.
A
Physico-chemical process
2
Q
Photosynthesis is a physics-chemical process by which they use light energy to drive the synthesis of -
A
Organic compounds
3
Q
Which simple experiment proves that photosynthesis occurs only in the green parts of leaves in the presence of light -
A
To look for starch formation in 2 leaves -variegated leaf or leaf that was partially covered with black paper
4
Q
Which exp proves that CO2 was req for photosynthesis ?
A
A part of leaf is enclosed Ina test tube containing some KOH soaked cotton (which absorbs CO2 ) . On testing for the presence of starch , only the exposed part tested positive .
5
Q
______in the year _____ revealed the essential role of air in the growth of green plants .
A
Joseph priestly
1770
6
Q
_____ discovered O2 in the year __.
A
Joseph priestly
1774
7
Q
Joseph priestly in the year 1770 revealed -
A
Essential role of air in the growth of green plants .
8
Q
_____observed that a candle burning in a closed jar , soon gets extinguished .
A
Priestly
9
Q
What was Joseph priestly’s hypothesis ?
A
Plants restore to air whatever breathing animals and burning candles remove .
10
Q
Using a similar setup as the one used by PRIESTLY ,but by placing it once in the dark and once in the sunlight ,_____ showed that SUNLIGHT IS ESSENTIAL TO THE PLANT PROCESS (that purified the air )
A
Jan ingenhouz
11
Q
______ in an elegant experiment with an ______ plant showed that in bright sunlight , small bubbles were formed around the green parts while in the dark they did not .
A
Ingenhouz
12
Q
Who showed that it is ONLY THE GREEN PARTS OF THE PLANTS THAT COULD RELEASE OXYGEN .
A
JAN INGENHOUZ
13
Q
What did jan engenhouz show-
A
2 things
Sunlight is essential to photosynthesis.
Only green plant parts release oxygen
14
Q
In jan ingenhouzs’s experiment with an aquatic plant , small bubbles formed around the green parts were of -
A
O2
15
Q
In year ____ , ______ provided evidence for production of glucose when plants grow .
A
1854
Julius Von Sachs
16
Q
Julius Von Sachs showed that glucose is mainly stored as ______.
A
Starch
17
Q
______ showed that green substances (chlorophyll) are located special bodies (chloroplasts ).
A
Von Sachs
18
Q
What did Julius Von Sachs prove -
A
He found that GREEN PARTS is where GLUCOSE IS MADE and that the GLUCOSE is usually stored as STARCH .
19
Q
______ used a prism and split light into its spectral components and then illuminated a green algae , (CLADOPHORA ) placed in a suspension of aerobic bacteria
A
T.W.Engelmann
20
Q
The bacteria used in Engelmann’s experiment were used to detect sites of _____
A
O2 EVOLUTION
21
Q
_____observed that bacteria accumulated mainly in the region of blue and red light of the split spectrum .
A
TW Engelmann
22
Q
Who described the first ACTION SPECTRUM of photosynthesis ?
A
Engelmann
23
Q
_____spectra of photosynthesis resembles _____ roughly the ____spectra of ________ .
A
Action
Absorption
Chloro a and b
24
Q
What were Engelmann’s experiments and what did he observe?
A
Using a prism ,he split light into its spectral components and then illuminated green algae,CLADOPHORA placed in a suspension of AEROBIC bacteria . The bacteria were used to detect sited of O2 evolution .
He observed that bacteria accumulated in the region of blue and red light.
25
Empirical foramula of cabs -
CH2O
26
A milestone contribution to the understanding of photosynthesis was that made by a _____, ________.
Microbiologist
| Cornelius van Neil
27
______ based o his studies on green and purple bacteria , demonstrated that photosynthesis is a light -dependent rxn .
Cornelius van Neil
28
Cornelius van Neil worked on _______ and ____ bacteria and demonstrated ______.
Purple green
| Photosynthesis is a light-dependent rxn
29
Van Neil showed that H2 from a suitable _____ reduces ______ to ____ .
Oxidisable compound
CO2
Carbs
30
Write the expression based on van neil’s studies -
2 H2A + CO2 ———> 2A +CH2O+ H2O
31
In green plants _____ is the H donor and is oxidised to O2 .
H2O
32
Some organisms do not release O2 during photosynthesis .T/F
T
33
_____ is the H-donor for purple and green sulphur bacteria and the oxidation product is _____ or _____ depending on the organism and not O2 .
H2S
| S or SULPHATE
34
Who inferred that O2 evolved comes from water and not form CO2 .
Cornelius van Neil
| This was later proved by RADIOISOTOPIC tech
35
_____was proved using radioisotopic tech .
O2 is evolved from H2O
36
What did CORNELIUS van Neil prove ?
Photosynthesis is a light -dependent rxn in which H from a suitable oxidisable compound reduces CO2 to carbohydrates
37
_____cells in the leaves have a large number of chloroplasts .
MESOPHYLL cells
38
How to CHLOROPLASTS align themselves to get optimum quantity of incident light ?
Along the walls of the mesophyll cells
39
Within the chloroplasts , there is a _____ system consisting of grana, stroma lamella , and matrix stroma .
Membranous
40
The membranous system in chloroplasts consists of -
Grana
STROMA lamella
STROMA matrixa
41
There is a clear division of labour within the ___
Chloroplast
42
The membrane system in chloroplast is responsible for -
2 things-
Trapping light energy
Synthesis of ATP and NADPH
43
In _____ (part of membrane system ) , ENZYMATIC reactions synthesise SUGAR which in turn forms _____.
STROMA
| Starch
44
Rxns like trapping light energy and synthesis of NADPH and ATP are _____.
Light dependent
| Photochemical rxns
45
Dark reactions are also called -
Carbon rxns
46
We can separate the leaf pigments of any green plant through -
Paper chromatography
47
A chromatographic separation of the leaf pigments shows that the colour that we see in leaves is not due a a single pigment but due to _____ pigments .
4
48
What are the 4 main pigments of leaf -
```
Chloro a (bright or blue green )
Chloro b (yellow green )
Xanthophylls (yellow)
Carotenoids (yellow to yellow orange )
```
49
______ are substances that have an ability to absorb light , at SPECIFIC WAVELENGTHS .
Pigments
50
Wavelengths at which there is max absorption of ______ (blue and red regions ) also shows higher rate of ______.
Chloro a
| Photosynthesis
51
______ is the chief pigment associated with photosynthesis .
Chloro a
52
There is a complete one to one overlap between the ______ spectrum of chloro a and the ______ spectrum of photosynthesis.
Absorption
| Action
53
Most of the photosynthesis takes place in the ___ and _____ regions of the spectrum .
Blue
| Red
54
Some photosynthesis also takes place at other wavelengths of the visible spectrum (apart from blue and red ) .T/F
T
55
What are accessory pigments ? Name -
Chloro b
Xanthophyll
Carotenoids
Other thylakoids pigments that absorb light and transfer the energy to chloro a
56
______ enable a wider range of incoming light to be utilised for photosynthesis .
Accessory pigments .
57
_____prevent chloro a from photo-oxidation.
Accessory pigments
58
Light rxn or photochemical have includes __ , ____ and ___ .
light absorption
Water splitting
O2 release
Formation of high edgy chemical intermediates -ATP NADPH
59
The _____ are organised into ___ discreet photochemical _______ within the PS1 and PS2 .(light rxn)
Pigments
2
Light harvesting complexes (LHC)
60
The photosystems are named int he sequence of their _____.
Discovery
61
The ___ are made up of hundreds of pigment molecules bound to proteins .
LHC
62
Associated pigments protect chloro a from ________.
Photo-oxidation
63
Each photo system has all the pigments ( except chloro a ) forming a light harvesting system also called ______
Antennae
64
The pigments of photosystems forming an antennae help to make photosynthesis more EFFICIENT by -
Absorbing diff wavelengths of light
65
Which pigment in photosystems does not form a LHS or antennae -
One molecule of chloro a
66
The single chloro a molecule forms the ______ .
Reaction centre
67
The _____ is diff in both photosystems .
Reaction centre
68
In PS1 ,the reaction centre chloro a has an ABSORPTION peak at ______ ,hence is called _____ , while in PS2 it has absorption maxima at _______ , an is called _____
700nm
P700
680
P680
69
In photosystem ____ , the rxn centre chloro a absorbs 680nm of ___ light causing electrons to become excited and jump into an orbit farther from the atomic nucleus .
2
| Red
70
The electron from PS 2 are picked up by an electron acceptor which passes them to an _____ consisting of _______.
Electrons transport system
| Cytochromes
71
The ,movement of electrons through an ETS consisting on cytochromes is ___ in terms of ___ or __scale .
Downhill
Oxidation -reduction
Redox potential
72
The electrons from PS2 re not used up as they pass through ETS but are passed onto -
Pigments of PS1
73
The electrons in the rxn centre of PS1 also get excited when they receive __ light of wavelength ___.when does this happen ?
Red
700nm
When electrons from PS2 enter PS1
74
The excited e- from PS1 are transferred to another acceptor molecule that has ____.
Greater redox potential
75
The excited e- from PS1 move _____ , this time to a molecule of ___
Downhill
| Energy-rich NADP+
76
What do the electrons from PS1 finally do ?
Reduce NADP+ to NADPH and H+
77
The whole scheme of transfer of e- starting from PS2 ___ to the acceptor down the ETC to PS1 , excitation of e- , transfer to another acceptor and finally downhill to NADP+ reducing it to NADPH + H+ is called __
Uphill
| Z-scheme
78
The e- transfer scheme is called Z-scheme due to its __.
Characteristic shape
79
The Z shape of the scheme is formed when all the carriers are placed in a sequence on a ____.
Redox potential scale
80
Electrons from PS2 are transported _____ to the acceptor (up/downhill)
Uphill
81
How does PS22 supply e- continuously ?
E- removed from PS2 are replaced by e- available due to splitting of water .
82
The splitting of water is associated with PS __
2
83
Water is split into _ ,__ and _.
2H+
[O]
e-
84
The e- needed to replace those removed from PS1 are provided by -
PS2
85
Water s[plitting complex is associated with ps2 which is located on the ____ side of membrane of _____.
Inner
| Thylakoid
86
Equation of water splitting -
2 H2O———> 4H+ +O2 +4e-
87
If ps2 is located on the inner side of membrane of thylakoid , then where are the protons and O2 likely to be released ?
Lumen of thylakoid
88
Living organism have the capability of extracting energy from ___substances and store this in the form of ____.
Oxidisable
| Bond energy
89
ATP carry energy in their ___
Chemical bonds
90
ATP is synthesised by cells (in _ and __ ) is named _____.
Mitochondria
Chloroplast
Phosphorylation
91
______ is the synthesis of ATP from ADP and inorganic phosphate in the presence of light .
Photophosphorylation
92
When the 2 PS work in a series , a process called ________ occurs.
Non-cyclic photo-phosphorylation
93
The 2 PSs are connected through an -
ETC
94
What is synthesised at the end of non-cyclic photophosphorylation ?
ATP and NADPH + H+
95
Photophosphorylation is the synthesis of _____, from ___ and ____in the presence of light .
ATP
ADP
Inorganic phosphate
96
When only ____ is functional , the e- is circulated within the photosystem and cyclic phosphorylation occurs .
PS1
97
Cyclic phosphorylation occurs in the ______ of chloroplast .
STROMA lamella
98
The _______ has both PS1 and PS2 , therefore non-cyclic phosphorylation occurs here .
Membrane or lamella of grana
99
The _____ lack PS2 , therefore cyclic-phosphorylation occurs here.
STROMA lamella membrane
100
The STROMA lamella membrane lacks _ and _____ .
Both PS2 and NADP reductase enzyme .
| Cyclic phos. Occurs here
101
In cyclic phosphorylation the excited e- does not pass on to ___ but are cycled back to ____ through the ETC
NADP+
| PS1
102
The end products of cyclic phosphorylation .
Only ATP
103
_____ phosphorylation occurs when ONLY LIGHT of wavelengths BEYOND 680nm are available for excitation .
Cyclic
104
Cyclic phos occurs when only light of wavelengths ______ are available for excitation .
Beyond 680nm
105
The ___ hypothesis has been put forward to explain the mechanism of ATP synthesis in the chloroplast .
Chemiosmotic
106
Like in _____ , in photosynthesis too , ATP synthesis is linked to development of a _____ across a membrane .
Respiration
| Proton gradient
107
What is the diff in ATP synthesis in respiration and photosynthesis ?
In photosynthesis , proton accumulation is inside the lumen (inside the membrane )
In respiration , protons accumulate in the intermembrane space of mito
When e- move through ETS .
108
In photosynthesis , protons accumulation is on the ______ side of membrane .
While in respiration , protons accumulate in _______.
Inner (lumen )
| Intermembrane space
109
Why do. Protons or H+ions accumulate on the inner side of the membrane ?
Since splitting of water takes place on the inner side of the membrane , therefore H+ ions produced by splitting of water accumulate within the lumen of the thylakoid .
110
As electrons move through the photosystems , protons are transported ______ the ____.
Across the membrane
111
Primary acceptor of e- is located on the ______ side of membrane.
Towards the outer side
112
The primary acceptor of e- transfers its e- not to a _____ but to a __.
e- carrier
| H Carrier
113
As e- move through the PSs , _____ are transported across the membrane . Why ?
Protons
Becoz prim acceptor of e-(plastoquinone ) transfers its e- to a H carrier . This H carrier removes a proton from the stroma while transporting an e-.
114
______ removes a proton from the stroma while transporting an e-.
H carrier
115
Name the prim acceptor of e- (from PS2)
Plastoquinone
116
Name the H carrier which removes a proton from the stroma while transferring an e-
Cytochrome B6f
117
The H carrier passes on its e- to the e- carrier located on the _____ side of the membrane of thylakoid .
Inner
118
What happens when the H carrier passes on its e- to the e- carrier on the inner side of the membrane ?
The proton (which H carrier was carrying after removing it from the stroma {outside thylakoid} )is released into the inner side or LUMEN of the membrane of thylakoid .
119
The NADP REDUCTASE enzyme is located on the ______ side of the membrane .
STROMA (outer)
120
Along with the e- that come from acceptor e- of PS1 , ___ are necessary for the reduction of NADPH + H+
PROTONS
121
Protons are necessary for the reduction of _____ . Where do they come from ?
NADP to NADPH and H+
| These protons are removed from the stroma .
122
Within the chloroplast , protons in the ______ dec in number , while in the _____ ,ther is accumulation of e- .
STROMA
| Lumen
123
State 3 ways in which protons accumulate in the lumen of thylakoid -
1) protons or H+ released due to splitting of water ( in PS2 which is locate on the inner side of membrane )
2) prim acceptor of e- (outer side ) transfers e- to a H+ carrier ,therefore the H+ carrier removes a proton from the stroma , while transporting this e- . When it passes its e- to the e-carrier on the inner side , it releases the proton into the lumen .
3) protons are necessary for the reduction of NADP , so they are removed from the stroma .
124
Name the e- carrier to which H+ carrier transfers its e- ?
Plastocyanin
125
Due to the proton gradient across the thylakoid membrane , pH decreases in the _____ .
Lumen
| Due to inc in H+
126
The breakdown of proton gradient leads to the _______.
Synthesis of ATP
127
The proton gradient is broken down due to the movement of protons across the membrane to the STROMA through the _____ of the _____ of the _______ .
Transmembrane channel
CFo
ATP synthase
128
The ATP synthase enzyme consists of 2 parts :
CFo
| CF1
129
The _____ part of ATP synthase forms the transmembrane channel .
CFo
130
The CFo part f ATP synthase carriers out ________ of protons across the membrane .
Facilitated diffusion
131
The ____part of ATP synthase is embedded in the thylakoid membrane .
CFo
132
The ____ portion of ATP synthase protrudes on the OUTER SURFACE OF THYLAKOID MEMBRANE on the side that faces STROMA .
CF1
133
The breakdown of the gradient provides enough energy to cause a ________ change in the ____ .
Conformational change
| CF 1
134
WHAT makes the enzyme ATP synthase synthesise several molecules of energy-packed ATP ?
Breakdown of proton gradient which causes conformational change in the CF1 parts of ATP synthase
135
Chemiosmosis requires a ___,_____, _____ and _______.
Membrane
Proton pump
Proton gradient
ATP synthase
136
Energy is used to pump ____ across a membrane , to create a gradient or a high conc of ____ within the ______ .
Protons
Protons
thylakoid lumen
137
______ has a channel that allows DIFFUSION of protons back across the membrane .
ATP synthase
| This process releases enough energy to activate atp synthase enzyme for the formation of atp
138
Along with the NADPH , ATP is used immediately in the biosynthetic phase .T/F
T
139
______ is responsible for fixing CO2 and synthesis of sugars .
Biosynthetic phase
140
Products of light rxn -
ATP
NADPH
O2
141
Immediately after light becomes unavailable , the _____ continues for some time and then _____ .
Biosynthetic phase
| Stops
142
If light is made available ,_____ starts again .
Biosynthetic (dark)
| Also light
143
Just after world war 2 , among the several efforts to put RADIOISOTOPES to use ,the work of ____ is exemplary .
Melvin Calvin
144
The use of _____ by Melvin Calvin in _____ studies led to the discovery of _____.
Radioactive C14
Algal photosynthesis
First CO2 fixation product - 3 C organic acid
145
Biosynthetic pathway is also called ______ and why ?
Calvin cycle
| He contributed to working out the complete biosynthetic pathway .
146
The first CO2 fixation product was __________
3-phosphoglyceric acid (PGA)
| 3-C organic acid
147
CO2 assimilation during photosynthesis is said to be of _____ main types .
2
148
What is the basis of division of CO2 assimilation into 2 main types ?
1st - those plants that produce C3 acid (PGA )as the first product o CO2 fixation - C 3 pathway
2nd- those plants that have C4 acid (OAA) as the first product -C4 pathway
149
How many C atoms would a molecule have which after accepting CO2 would have 3 C PGA ?
5
150
The primary acceptor (fixer) of CO2 is a ______ sugar called ____.
5 C ketone sugar
| RuBP ribulose bisphosphate
151
Calvin showed that the pathway operated in a _____ manner .
Cyclic
152
The CALVIN PATHWAY occurs in _____
All photosynthetic plants
| It doesn’t matter whether they have C3 , C4 or any other pathways
153
Calvin cycle can be described under ____ stages .name —
3
Carboxylation
Reduction
Regeneration
154
_____ is the fixation of CO2 into a stable organic intermediate .
Carboxylation
155
______ is the most crucial step of the Calvin cycle .
Carboxylation
156
In Calvin cycle , _____ is utilised for the carboxylation of ___
CO2
| RuBP
157
Carboxylation is catalysed by _____ which results in the formation of ___
Enzyme RuBP carboxylase
| 2 molecules of 3-PGA
158
RuBP carboxylase also has ____ activity so its correct name is -
Oxygenase
| RuBisCO
159
Series of reaction that lead to the formation of GLUCOSE ( in Calvin cycle ) are-
Reduction
160
Reduction step involves utilisation of _____for ____and_____for_____ per CO2 fixed .
2 molecules of ATP
Phosphorylation
2 molecules of NADPH
Reduction
161
The fixation of _____molecules of CO2 and _____ turns of the cycle are req for the formation of _____molecules of GLUCOSE from Calvin pathway .
6
6
1
162
_____ of the c2 acceptor molecule Rubpi crucial if the cycle is to continue uninterrupted .
Regeneration
163
Which step involves utilisation of 2 molecules of ATP and NADPH (per turn )
Reduction
| 3PGA ——reduction———>triose phosphate
164
The regeneration steps require _____ for ____ to form RuBP (again )
1 ATP
| Phosphorylation
165
For every CO2 molecule entering the Calvin cycle ____ ATP and ___ NADPH are req.
3 molecules
| 2 molecules
166
To meet the difference in number of ATP and NADPH used in the DARK RXN that the ___takes place .
Cyclic phosphorylation
| Only ATP
167
What comes out of Calvin cycle ?
1 glucose
18 ADP
12 NADP
168
Plants that are adapted to ______ regions have C4 pathway .
Dry tropical regions
169
C4 plants use _____ as the main photosynthetic pathway .
C3 pathway
| Though C4 acid is the first fixation product
170
C4 plants have a special _____.
Leaf anatomy
171
Special features of C4 plants -
```
5
Special leaf anatomy
Tolerate high temp
Show response to high light intensities
Lack photorespiration
have Greater productivity of biomass
```
172
C4 plants respond to ____ light intensities .
High
173
C3 and C4 have same type of MESOPHYLL .T/F ?
F
174
The particularly large cells around the ______of the C4 plants are called ____.
Vascular bundles
| Bundle sheath cells
175
C4 pants have large cells around vascular bundles called bundle sheath cells .this anatomy is called -
Kranz anatomy
176
Kranz means __ and is a reflection of the ______ of cells .
Wreath
| Arrangement
177
The ___may form SEVERAL LAYERS around the vascular bundles .
Bundle sheath cells
178
Name 2 C4 plants .
Maize
| Sorghum
179
Bundle sheath cells are characterised by ____number of CHLOROPLASTS , ____walls IMPERVIOUS to____ and __ intercellular spaces .
Large
Thick
Gaseous exchange
No
180
Presence of bundle sheath cells is a characteristic of -
C4 plants
181
C4 pathway has been named __ and is a __ pathway .
Hatch and slack
| Cyclic
182
Describe kranz anatomy -
Bundle sheath cells form several layers around the vascular bundles and have large no of chloroplasts ,thick walls impervious to gaseous exchange and no intercellular spaces
183
The primary CO2 acceptor in C4 -
3 C molecule -PEP phosphoenol pyruvate
| In C3 - 5 C RuBP
184
The primary CO2 acceptor in C4 (PEP) is found in ____ cells .
MESOPHYLL
185
The enzyme req for prim CO2 fixation is C4 -
PEPcase
186
The mesophyll cells in C4 plants lack -
```
RuBisCO enzyme
(Have PEPcase)
```
187
The C4 acid ____ is formed in ______ cells .
OAA
MESOPHYLL
(PEP ——PEPcase——>OAA)
188
The OAA forms other ____ compounds like. ___and _____.
4C
Malic acid
Aspartic acid
189
OAA forms aspartic acid and malic acid in the __cells itself which are then transported to the __cells .
MESOPHYLL
| Bundle sheath cells
190
In the BUNDLE SHEATH CELLS ,the C4 acids (malic or aspartic) are broken down to release ____and _____.
CO2
| 3C molecule
191
The 3C compound is transported back to the _____ where it is converted to _____again ,thus completing the cycle .
MESOPHYLL
| PEP
192
The __released in the BUNDLE sheath cells enters the C3 or Calvin pathway .
CO2
193
C3 (Calvin) cycle occurs in the __cells in C3 pants while in C4 plants it occurs in _cells
MESOPHYLL
| Bundle sheath cells
194
In _____cells the C4 acids are broken down to release CO2 and 3 C compound .
Bundle sheath cells
| In mesophyll cells -C4 acids are formed
195
In bundle sheath cells , the C4 acids are converted to CO2 and C3 acid through _____.
Decarboxylation
196
In C4 plants , regeneration occurs in ____cells .
MESOPHYLL cells
| Where , C3 acid——-regeneration——>PEP
197
In C4 plants , decarboxylation occurs in ___Cells .
Bundle sheath cells
198
In C4 , bundle sheath cells are rich in ______.
RuBisCO
| Lack PEPcase
199
Calvin pathway in C4 plants takes place in _____cells .
Bundle sheath cells
200
Calvin cycle occurs in all mesophyll cells of C3 pant .T/F
T
201
Give the equation of ist CO2 fixation step in C3 .
RuBP + CO2 —RuBisCO—>2* 3PGA
202
_____ is the most abundant enzyme in the WORLD .
RuBisCO
203
RuBisCO is characterised by the fact that its _____can bind with both _and__.
Active site
CO2
O2
204
Rubisco has a much greater affinity for ___when CO2: O2 ratio is nearly equal .
CO2
205
The binding in rubisco is ______.
Competitive
206
It is the ___of CO2 and o2 that determines which will bind to the enzyme .
Relative conc
207
In C3 plants , some ___des bind with rubisco ,hence ___is DECREASED .
O2
| CO2 fixation
208
When instead of CO2 ,o2 binds with with rubisco (shows RuBP oxygenase activity now)then RuBP binds with o2 to form _____and _____.
Phosphoglycerate
| Phosphoglycolate (2C)
209
in photorespiration ,there is neither synthesis of __ nor __.
Sugars
| ATP
210
Photorespiration results in the release of ____ with the ___ .
CO2
| Utilisation of atp
211
In _____ ,there is no synthesis of atp or nadph .
Photorespiration
212
What is photorespiration .
When instead of CO2 , o2 combines with rubisco (its carboxylation activity is dec and oxygenase part functions ) . Here RuBP instead of being converted to PGA binds with o2 to form 1 molecule of PHOSPHOGLYCERATE or PHOSPHOGLYCOLATE (2C)
213
In C4 plants photorespiration does not occur .why ?
Becoz they have a mechanism that inc. the conc of CO2 at the enzyme site .
214
In C4 plants the mechanism that inc the conc of CO2 occurs when : C4 acid from the __cells is broken down in the __ cells to release CO2.
MESOPHYLL
| Bundle sheath cells
215
When C4 acid is broken down in the bundle sheath to release CO2 , it results in increasing the ____of CO2 .
Intracellular conc
216
Increasing intracellular conc of CO2 ensures that -
Rubisco functions as carboxylase minimising oxygenase activity
217
Tolerance to high temp is shown by __ plants .
C4
218
The plant factors that affect photosynthesis -
Number , size , age and orientation of :: leaves ,mesophyll cells and chloroplasts
Internal CO2 conc
Amount of chlorophyll
219
The plant or internal factors are dependent on the ______ and the _____ of the plant .
Genetic predisposition
| Growth
220
The external factors affecting photosynthesis are :
Availability of sunlight , temp , CO2 conc and water
221
Though several factors interact and simultaneously affect photosynthesis , only one factor is the major cause or is the one that ____ the rate .
Limits
222
At any point ,the rate will be determined by the factor available at _____ levels .
Sub-optimal
223
When several factors affect any chemical. Process , _____ law comes into effect .
Blackman’s law of limiting factors
224
According to Blackman’s law of limiting factors , if a chemical process is affected by more than one factor ,then its rate will be determined by the factor which is NEAREST to its ______.
Minimal value
225
The factor nearest to its minimal value affects photosynthesis _____directly /indirectly if its quantity is changed .
Directly
226
Blackman’s law of limiting factors as given in the year -
1905
227
Despite the presence of a green leaf and optimal light and CO2 conditions , the plant ____ photosynthesise if the temp is ______ .
may not
| Very low
228
We need to distinguish between light _____, light ____and the duration of ______.
Quality
Intensity
Exposure to light
229
There is a ___relationship between incident light and CO2 fixation rates at ___light intensities .
Linear
| Low
230
There is a linear relationship between _____and ___ at ___
Incident light
CO2 fixation rates
Low light intensities
231
At _____light INTENSITIES , gradually the rate (CO2 fixation )does not show further increase .
High
232
Why at high light intensities ,the rate ( of CO2 fixation) does not show further if ?
As other factors become limiting
233
Light saturation occurs at __% of the full sunlight .
10%
234
For what kind of plants LIGHT is a limiting factor ?
Plants in shade or in dense forests 🌳
235
Except for plants in shade or in dense forests ,_____is rarely a limiting factor .
Light
236
Increase in INCIDENT LIGHT beyond a point causes the ______ and a dec in photosynthesis .
Breakdown of chlorophyll
237
______is the major limiting factor for photosynthesis .
CO2
238
The conc of CO2 is ____ in the atm ,between ____and____%.
Very low
| 0.03 -0.04%
239
Increase in conc of CO2 upto ___% can cause an INCREASE IN CO2 FIXATION RATES .
0.05%
240
Beyond which level can CO2 become damaging over long periods ?
0.05%
241
The C3 and C4 plants respond diff to ___conc .
CO2
242
At low light intensities , ____group (C3 /C4) responds to high CO2 conditions .
Neither
243
At high light intensities _ C3 /C4 show inc in the rates of photosynthesis .
Both c3 and C4
244
C4 plants show saturation at about _____(co2 conc )
360 uIL- (co2 conc)
245
C3 plants respond to _____co2 conc and saturation is seen only beyond __
Increased
| 450 uIL-
246
___availability of co2 levels is limiting to the ____plants .
Current
| C3
247
At _____ , light intensities , both c3 and C4 show inc in the rates of photosynthesis .
High
| At low intensity ,neither respond
248
Which fact has been used for some GREEN HOUSE crops ?
The fact that c3 plants respond to HIGHER CO2 CONC by showing increased rates of photosynthesis leading to higher productivity .
249
Name some greenhouse crops (which grow in higher co2 conc)
Tomatoes 🍅
Bell pepper
(These are c3 plants )
250
_____plants are allowed to grow in CO2 enriched atm that leads to higher yields .
C3
| Tomatoes 🍅 and bell pepper
251
The dark rxn being __Are ____controlled .
Enzymatic
| Temp
252
____ rxns are also TEMP sensitive but they are affected to a much ____ extent .
Light
| Lesser
253
The ____plants respond to higher temp and show higher rates of photosynthesis .
C4
254
_____plants have a much LOWER TEMP OPTIMUM .
C3
| Respond to low temp properly ,unlike C4
255
The TEMP OPTIMUM for photosynthesis of diff plants also depends on the ___
Habitat that they are adapted to
256
____plants have a HIGHER TEMP OPTIMUM than the plants adapted to _____climates . (Tropical /temperate)
Tropical
| Temperate
257
____rxns are temperature controlled.
Dark
| Becoz they are enzymatic
258
Even though ____is one of the reactants in the light rxn , its effect as a factor is more through its effect on the plant , rather Han directly on photosynthesis.
Water
259
Water stress causes ____ hence reducing _____.
Stomata to close
| The co2 availability
260
Water stress also makes leaves ___ ,hence reducing the _____ of leaves and their _____ as well .
Wilt
SA
Metabolic activity
261
_____causes the stomata to close and makes leaves wilt .
Water stress
262
What happens when a leaf wilts .
Leaf 🍃 SA is reduced and therefore their metabolic activity
263
Prim Electron acceptor of PS 1 -
An Fe-S protein
