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INTRODUCTION
"Photosynthesis is a Physicochemical or photo-biochemical process (anabolic & endergonic) in which
organic compounds (carbohydrates) are synthesized from the inorganic raw material (H2O & CO2) in
presence of light & pigments. O2 is evolved as a by product".
Light energy is conserved into chemical energy by photosynthesis.
Pigment
 C H O +6O  + 6H O
6CO +12H O  
2
2
light
6
12
6
2
2
First photosynthetic organism are bacteria but first oxygenic photosynthesis started in cyanobacteria. (BGA)
EARLY EXPERIMENTS
J. Priestley : He carried out very interesting experiment on Bell jar, Rat, Pudina & Candle. He came to
conclude that plants purifyair (burning of candles) and gaseous exchange occurs during photosynthesis Discovers of oxygen.
Jan Ingenhousz : He explained the importance of light and green colour and also suggested the O2 releases
in the presence of light bygreen parts.
J. V. Sachs : Recognised the relation among photosynthesis, chloroplast and starch.
Englemann : Described action spectrum of photosynthesis with the help of Spirogyra/Cladophora and aerobic bacteriaexperiment.
Van Niel : infered that oxygen comes from water in photosynthesis of higher plants.
Light
  C
H O +6H2 O+12S
6CO2+12H 2S 
chromatophore
6 12 6
Ruben Hasid and Kamen : Used radiaisatopic (Bacteria)
(O18) to show experimentally that O in photosynthesis
2
comes from water.
Hill Reaction - Experiment on isolated thylakoids (Stelaria plant) studyof light reaction, which is called as
Hill Reaction.
O2gas liberated from photolysis of HgO, only in the presence of suitable e- and H+ acceptor. (DCPIP
(Dichlorophenol Indophenol- a dye), ferricyanide, Hill reagents, NADP+)
1
A + H2O  AH2 + O2
2
Light
18 
6C O16
+12H O
C6H
O 16 + 6H2O+ 6 O18
Chlorophyll
2
2
2
12 6
PHOTOSYNTHESIS
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HOW MANY PIGMENTS ARE INVOLVED IN PHOTOSYNTHESIS
Chlorophyll - a C55H72O5N4Mg  CH3 grp. at IIIrd C of IInd pyrrole ring.
Chlorophyll - b C55H70O6N4Mg CHO group at IIIrd C of IInd pyrrole.
Chlorophyllsaremagnesiumporphyrincompounds. Porphyrinringconsistsoffour-pyrrolerings(Tetrapyrrole).
Generally 5-10% chlorophyll is present in chloroplasts.
Chlorophyll molecule has a Mg-porphyrin headand phytol tail. Headis hydrophilic and phytol tail is lipophilic
(hydrophobic).
Chl-a and carotenes are universal pigment, which are found in all O2 liberating photosynthetic organisms.
Chlorophylls are soluble onlyin organic solvents like ketons, ethers etc.
In paper chromatography/chromatogram Chlorophyll 'a' - bright or blue-green
Chlorophyll 'b' - yellow green/grass green.
Xanthophyll - yellow
Carotenoids - Yellow to yellow - orange
Chlorophyll synthesis:
ight
Succinyl CoA + Glycine Protochlorophyll (Protochlorophyllide) L

 Chlorophyll.
2H
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PHOTOSYNTHESIS
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400-700 nm light is used in photosynthesis and it is known as PAR (Photosynthesis active radiation)
WHAT IS LIGHT REACTION
Emerson & Arnold - worked on Chlorella and gave the concept of two photosystem or two pigment
systems.
When theygave only monochromatic light, longer than 680 nm wavelength, then quantum yield is suddenly
dropped down, this event is called as red drop.
When Emerson gave light, shorter and greater than 680 nm (combined light) then photosynthetic, activity
increases, this is called as Emerson effect or enhancement effect.
i) 680 nm   PS - I (cyclic process) red drop appears.
ii) 680 nm + 680t nm (Mixed light)  Both cyclic & non cyclic operates. (Emerson effect)
The PS II is located in the appressed region of granal thylakoids and PS I in non appressed region of grana
and stromathylakoids.
PS-I in
Non-appressed region
(Exposed surface)
Stroma
lamellae
PS-II om
appressed
region
ELECTRON TRANSPORT, SPLITTINGOF WATER AND PHOTOPHOSPHORYLATION
Light reaction/Hill reaction/Photochemical reaction/Generation of assimilatory powers (NADPH2 +ATPs).
I). Z-Scheme/Non-cyclic ETS and PhotophosphorylationPHOTOSYNTHESIS
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Both PS-I and PS-II involved in non cyclic ETS.
PS-II (P-680) consists of Chl-a-660, Chl-a-673, Chl-a-680 (Reaction centre), Chl-b and carotenoids.
It occurs on grana thylakoids only.
The e- ejected from PS-II never back to chl-a-680 (reaction centre) & finally gained by NADP. Thus gap of
e- in PS-II is filled by photolysis of water as a result, oxygen evolution occurs in Z-scheme and there is
formation ofATP & NADPH2.
Pheophytin is considered as Ist e- acceptor in Z-scheme.
Chemiosmosis
Low
*
P70
0
2eFRS 2e-
*
P680
2e -
NADP++2H+
Fd
2H+
Pheo 2ePQ 2eCyt b6f 2e2H+
PC 2e(lumen)
NADPH+H+
PS-I
P700
PS-II
P680
High
H2 O
Z - Scheme
1
2H++ O 2
2
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PHOTOSYNTHESIS
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II) Cyclic ETS and Photophosphorylation
In cyclic ETS, only PS-I works, which consists of Chl-'a'-670, Chl-a-683, Chl-'a'-695, carotenoids, some
molecules of chl-'b' & reaction centre-Chl-'a'-700/P-700.
It occurs at grana thylakoids and stroma thylakoids. Stroma lamellae/stroma thylakoids lack PS II and enzyme NADP reductase.
During Cyclic ETS the electron ejected from reaction centre of PS-I, return back to its reaction centre so in
cyclic ETS, no oxygen evolution occurs, because photolysis of water is absent.
NADPH, (reducing power) is not formed in cyclic process.
Plastocyanin (PC) is Cu-containing blue coloured chromoprotein in cyclic ETS.
According to modern researches in cyclic ETS first e- acceptor in PS-I is FRS (Ferredoxin Reducing Substance), which is a Fe-S containing Protein.
2e- P700
FRS
Fd
(Stroma)
2H
+
Cyt-b6
PQ
2H+(lumen)
Cyt-f 2ePC
2e-
PS-I
P700
Cyclic photophosphorylation
Cyclic photophosphorylation
Non-cyclic photophosphorylation
1) Only PS-I involved in cyclic process.
1) Both PS-II & PS-I work in non- cyclic process.
2) The e expelled from chl-700 is cycled back.
2) The e- expelled from reaction center is not cycled
back. Its loss is compensated by e- from H
O.
2
3) Photolysis of water and evolution of O2
3) Photolysis of water and evolution of O2 takes place.
does not take place.
4) NADP+ is not reduced.
4) NADP+ is reduced to NADPH.
5) Onlycyclic photophosphorylation activated
5) Activated by wavelength < 680 nm.
when light available is above 680 nm.
Quantum requirement The number of light Quanta or photons required for the evolution of 1 mol. of O2 in photosynthesis.
Emerson calculated that the quantum requirement is 8.
Quantum Yield Thenumberofoxygen molecule evolved byone quantumof light in photosynthesis is calledas Quantum yield.
Hence the quantum yield is 0.125 or 12.5%
CHEMIOSMOTIC THEORY:
Proposed by Peter Mitchell to explain the mechanism of ATP formation.
During ETC of photosynthesis concentration of H+ graduallyincreases in thylakoid lumen. During non cyclic
photophoshorylation there are three causes of difference in H+ ion concentration i) Photolysis of H2O produces H+
ii) PQ shifting of H+ ion from stroma to lumen.
PHOTOSYNTHESIS
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iii) NADP reductase mediated utilisation of H+ from stroma.
This differential H+ ion concentration leads to development of proton gradient and electrical potential across
thylakoidmemberane. Bothprotongradientandelectricalpotential collectivelycalledprotonmotiveforce(PMF)
PMF do not allow stay of H+ ions in lumen so H+ start to move towards stroma through CF 0-CF 1particle
+
selectively. The passage of H ions leads to activation of ATP synthase and it forms ATP from ADPand Pi.
GOLDEN KEY POINTS
1. Glutamic acid may also act as precursor or starting molecule for chlorophyll biosynthesis.
2. Chl-a is also present in antennae molecules.
3. With respect to 1O2 release in non-cyclic process total 4e - flow through the process and 2NADPH+H +are
4.
5.
6.
7.
formed.
OEC(Oxygen Evolvingcomplex) isasmallproteincomplexalsocalled Z-enzymeanditisassociatedwith P680.
8H+ are released into lumen with respect to the release of 1O2 in non-cyclic process.
Chemiosmotic theoryis applicable for both chloroplast & mitochondria because both showATP synthesis by
usingproton gradient.
12H2O are required per glucose synthesis in photosynthesis because all O2 released in the process comes
onlv, from H2O.
1. Green light is mainly absorbed by
1) Chl-a
2) Chl-b
3) Carotenoids
4) Phytochrome
2. In non-cyclic photophosphorylation an FeS protein complex acts as
1) Mobile e carrier
2) Mobile H carrier
3) Primary e- acceptor for PS-II
4) Primary e- acceptor for PS-I
3. Lowest pH inside chloroplast in day time must be found in
1) Stroma
2) lumen
3) Intermembrane space
4)Thylakoid membrane
4. Proton pump in thylakoid membrane is
1) PC
2) Pheophytin
3) Fd
4) PQ
5. ATPsynthesis in chloroplast occurs
1) In stroma
2) At CF0
3) At CF1
4) PS-II & PS-I
1) 3
2) 4
3) 2
4) 4
5) 3
[B] Dark Reaction / Blackman Reaction / Calvin cycle / C3-Cycle / Biochemical phase / Carbon assimilation / photosynthetic carbon reduction cycle (PCR-Cycle) / Reductive pentose phosphates pathway
Dark reaction, was discovered by Blackman but Calvin, Benson presented these reactions in cyclic manne:
and thus called as Calvin cycle.
Ist stable compound of Calvin cycle is 3C-PGA (Phosphoglyceric acid) thus Calvin cycle is called as C3cycle (First compound is unstable, 6C keto acid)
Studyby Calvin was on green algae Chlorella & Scenedesmus. During his experiment he usee chromatography & radioisotopy (C14) techniques for detecting reactions of C 3-cycle.
Rubisco (Ribulose bis-phosphate carboxylase-oxygenase) is main enzyme in C3-cycle, which is present ir
stroma. Rubisco is most abundant enzyme.
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PHOTOSYNTHESIS
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CO2-acceptor in Calvin cycle is RuBP.
6 turns of Calvin cycle are required for the formation of one glucose.
Atmosphere
(RuBP)
Ribulose-1,5-biphosphate
(5C)
ADP
1
CO2+H2O
Carboxylation
3-phosphoglycerate (3-PGA)
(3C) (2 molecules)
Regenaration 3 Calvin - Cycle
2ATP+2NADPH+H+
ATP
2
(3-PGAL)
Triose
phosphate (3C)
Reduction
2ADP+2P+2NADP+
Sucrose, Starch
Note : First stable six carbon sugar formed in plants is fructose-1,6-Bis phosphate (Glycolytic reversal).
CO2 concentrating mechanism/Co-operative photosynthesis/Dicarboxylic acid cycle (DCA cycle) /
C4 cycle/Hatch & Slack Pathway
Kortschak and Hartt first observed that 4C, OAA (Oxaloacetic Acid) is formed during dark reaction in
sugarcane leaves.
Hatch & Slack (Australia) (1967). Studied in detail and proposed pathwayfor dark reactions in sugarcane &
maize leaves.
C4-cycle occurs in 1500 species of 19 families of angiosperm, but most of the plants are monocots, which
belong to Graminae (Sugarcane, Maize, Sorghum) & Cyperaceae.
Kranz (Wreath) anatomy - Present in leaves of C4 plants. Which has following features
i) Green bundle sheath cells (BS cells) present around the vascular bundles.
ii) Dimorphic chloroplasts present in leaf cells. Chloroplast of B.S. cells or Kranz cells are larger and without
grana.
Mesophyll chloroplast are small and with grana.
Rubisco present in BS cells, while PEPCase in mesophyll cells.
Photosynthetically C4 plants are more efficient as there is no photorespiration, Because at the site of Rubisco
(BS cells) no O2 is release & mesophyll cells pumps more CO2 for C3 cycle.
C4-plants found in tropical habitats and adaptedthemselves, with high temperature, low water availabilityand
intense light. No photorespiratoryloss.
Primary CO2 acceptor in C4 is PEP (Phosphoenol Pyruvate). (3C-compound). First carboxylation in C4cycle occurs by PEPCase in mesophyll cytoplasm, while second carboxylation or final C(X fixation by C3
cycle occurs in bundle sheath cells.
12 NADPH2 & 30 ATP needed for production of 1 Hexose (Glucose) in C4-plants.
PHOTOSYNTHESIS
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Pyruvate phosphate dikinase (PPDK) (ATP  AMP) is a low temperature sensitive enzyme of C4 and CAM
plants due to this C4 plants show poor rate of photosynthesis at low temperature.
Diagrammatic representation of the Hatch and Slack Pathway in NCERT
Atmospheric CO2
Plasma membrane
Mesophyll
cell
Cell wall
HCO3- Phosphoenolpyruvate
(3C)
2ATP
Fixation
Regeneration
OAA (C4acid)
NADPH
NADP
PEP(C3 acid)
Malic/Aspartic acid(C4 acid)
Bundle
sheath
cell
Transport
Transport
Fixation by
Calvin Cycle
Malic/Aspartic acid
(C4 acid)
CO2
Pyruvic acid (C3 acid)
Decarboxylation
Special features of C4 plants
1) C4 plants are more efficient photosynthetic plants at present CO2 concentration.
2) C4 plants posses low CO2 compensation points. (0-10 ppm)
3) The productivity (fertility) in C4 plants, does not increase when CO2 concentration is increased above
current atm level, because present level of atmospheric CO2 is generallynot limiting factor for C4 plants.
4) Mesophyll cells pump more CO2 for Calvin cycle. Thus concentration of CO2 is high around the site of
Rubisco in C4 plants, thus little or no chance of photorespiration.
Characteristics
C3 Plants
C4 Plants
Choose from
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PHOTOSYNTHESIS
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Cell type in which the Calvin
Mesophyll
Bundle sheath
takes place
Mesophyll/Bundle cycle
sheath/both
Cell type inwhich the initial
carboxylation reaction occurs
Mesophyll
Mesophyll
How many cell types does the
One
Two
Mesophyll/Bundle
sheath /both
Two: Bundle sheath and
mesophyll
leaf have that fix CO2
One: Mesophyll
Three: Bundle sheath,
palisade,spongymesophyll
Which is the primary CO2
acceptor
RuBP
PEP
RuBP/PEP/PGA
Number of carbons in the
5
3
5/4/3
PGA
OAA
PGA/OAA/RuBP/PEP
CO2 fixation product
Does the plant have RuBisCO?
3
Yes
4
Yes
3/4/5
Yes/No/Not always
Does the plant have PEP Case?
Yes
Yes
Yes/No/Not always
Which cells in the plant have
Rubisco?
Mesophyll
Bundle sheath
Mesophyll/Bundle sheath/
none
CO2 fixation rateunder high light
conditions
Medium
High
Low/ high/ medium
Whether photorespiration is
Negligible
Negligible
High/negligible/sometimes
High
Negligible
High/negligible/ sometimes
High
Negligible
High/negligible/sometimes
Negligible
Negligible
High/negligible/sometimes
Temperature optimum
400C
20-250C
30-400C
30-400C/20-250C/above
Examples
Wheat, Rice
Maize,Sugarcane,
primary CO2 acceptor
Which is the primary CO2
fixation product
No. of carbons in the primary
present at low light intensities
Whether photorespiration is
present athighlight intensities
Whether photorespiration
would be present at low
CO2 concentrations
Whether photorespiration
would be present at high
CO2 concentrations
Sorghum
PHOTOSYNTHESIS
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CAM-Plants / Crassulacean acid metabolism / Dark CO2 fixation / Dark Acidification
Oleary and Rouhani discovered that CO2 fixation occurs in night in members of Crassulaceae family. Succulent xerophyticplants.
In CAM plants stomata open in night and closed during day (scotoactive type).
Example of CAM plants are Kalanchoe, Bryophyllum, Opuntia, Agave, Aloe, Euphorbia, Pineapple,
Welwitschia (Gymnosperm) etc.
Primary acceptor of CO2 is PEP (Phosphoenol pyruvate) and oxaloacetic acid is the first stable product of
carboxylation reaction.
PEP carboxylase & RuBisCO present in mesophyll cells. (No Kranz-anatomy)
In CAM plants 30 ATP and 12 NADPH2 are required for 1 glucose synthesis.
CAM plants exhibits adaptation for conserving water.
CAM Pathway
Mesophyll cell
CO2 H2O
CO2
Stomata open
H2 O
CO2 H2O
Pi
AMP + ppi
PEP
ATP
(3C)
PPDK
HCO3-
OAA(4C)
PEP
case
PEP(3C)
Pyruvate(3C)
NADPH+H+
NADPH+H+
NADP+
NADP+
Malate/Malic acid (4C)
Malic acid
Stomata closed
Malate/Malic acid (4C)
Chloroplast
Malic acid
Vacuole
During night (Acidification)
Starch
Calvin
Cycle
Chloroplast
Vacuole
During day (Deacidification)
Photosynthetic carbon oxidation cycle/C2 cycle/ Photorespiration/Glycolate-Metabolism
The light dependent uptake of O2 & release of CO2 in C3 photosynthetic cell is called photorespiration or C2
cycle.
Photorespiration operates during daytime in C3- plants & Rubisco acts as oxygenase at higher concentration
of O2 and low CO2 concentration in the C3 - green cells.
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PHOTOSYNTHESIS
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Photorespiration does not produceATP, NADPH & sugar but involves oxidation of organic compounds so It
is a wasteful process. It occurs in chloroplast, peroxisomes & mitochondria.
Chloroplast
O2
Phosphoglycolate+PGA
(2C)
(3C)
RuBP
+
PCR cycle
PGA
Pi
ADF + iP
ATP
Peroxisome
Glycerate
Glycolate (2C)
Glycerate
NAD+
NADH
Hydroxy pvruvate
Glycolate
Glyoxylate+H2O2
+NH2
NH2
Glycine
Mitochondrion
Serine (3C)
2 mol. Glycine (2C)
Serine (3C)
NH2
CO2
NAD+
NADH
Photorespiration/Photosynthetic carbon oxidation cycle.
FACTORS AFFECTINGPHOTOSYNTHESIS
Law of limiting factors - (Blackman) "When a process is conditioned to its rapidity by a number of factors,
then rate of process is limited by the pace of the slowest factor" (CO2, light, chlorophyll, water, temp.)
CO2 becominglimiting in clear sky, but light limiting in cloudydays and in dense forest.
Atmospheric CO2 is not limiting factor for C4 plants & submerged hydrophytes.
1) Light At low light intensitythere is a linear relationship between light intensityand rate of photosynthesis. But at high
light interbitythere is no farther increase in rate of photosynthesis.At veryhigh light intensity photooxidation
(solarization) of photosynthetic pigments mayoccur.
Intensity of light, at which rate of photosynthesis, becomes equal (or compensate) with the rate of respiration
in plants is known as light compensation point. (Net photosynthesis or net primaryproductivityat this point is
zero and no gaseous exchange between plant and atmosphere)
PHOTOSYNTHESIS
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Rate of photosynthesis
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C
B
A
D
Light intensity
2) Temperature
Optimum temp, for photosynthesis is 20-25°C for C3 plants and 30-40°C for C4 plants.
At high temp, rate of photosynthesis decreases due to denaturation of enzymes.
Dark reactions are more affected by temperature as compare to light reactions.?
3) CO2 (between 0.03 and 0.04 percent)
An increase in CO2 conc. upto 0.05% rate of photosynthesis is increased. Higher CO2 concentratic is toxic
to plant & also closes stomata.
CO2 concn at which CO2 fixation in photosynthesis is equal to volume of CO2 released in respiration
"CO2compensation point" (when plant saturated withfull light).
CO2 compensation point for C4 plants is 0-10 ppm, while for C3 plants it is 25-100 ppm.
Use of CO2
C4 plants (Hight light)
0 10 50
4) Water
C3 plants (High light)
100
200
300
360 400 450 500
S.P.
S.P.
CO2 in ppm
(S.P.=Saturation point)
Less availability of water reduces the rate of photosynthesis (stomata get closed, leaves become wilted and
slowenzymatic activities).
Plant Factors
i) Amountof Chlorophyll
ii) Leaf - Various leaf factors like leaf number, size, age and leaf orientation affect the photosynthesis
5) Inhibitors
DCMU(Diuron/Dichlorophenyl Dimethyl Urea) CMU(Monuron), PAN inhibit thephotosynthesisbyblocking
PS-II. They stop er flow between P-680 & PQ.
In cyclic ETS diquat, paraquat (Viologen dyes) inhibit er flow between P-700 & Fd.
All these chemicals are used as weedicides or herbicides.
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BACTERIAL PHOTOSYNTHESIS
Certain bacteria are capable for photosynthesis Eg Chlorobium (Green Sulphur), Chromatium (Purple Sulphur), Rhodospirillum, Rhodopseudomonas (Purple non sulphur).
Cyclic photophosphorylation is an important method in bacterial photosynthesis.
Absorption of Infra red spectrum takes place during bacterial photosynthesis thus no red drop.
PS II is absent, so Z-scheme is absent.
Reducing power generated during light reaction is NADH + H+.
Pigment system of bacteria denoted by - B-890 or 870
Evolution of O2 is not related to bacterial photosynthesis, because water is not e - and H + donor.
IR l ight
   C 6H 12O 6+H 2O+12S
6CO 2+12H 2S 
Pigments in chromotophores
SOME EXTRA POINTS
Function of accessorypigment is Converts elementaryor nasent oxygen to molecular/gaseous O2(Carotene).
Enhances the effeciencyof photosynthesis.
Prevent photooxidation (photodamaging) of pigment system.
Mg++ required for Rubisco & PEPcase
Ist formed unstable 6-C compound during Calvin cycle is 2 carboxy 3 Keto 1, 5 biphosphoribitol.
GOLDEN KEY POINTS
1.
2.
3.
4.
CO2 and O2 compete for the same active site on RuBisCO.
PEPCase is activated byblue light.
In photorespiration 25% of already fixed carbon is lost as CO2.
Light compensation point can be observed in open atmosphere in morning & evening but CO2 compensation
point can't be observed in open atmosphere.
5. NADP+ and ADP+ iPproduced in dark reaction are released into stroma and again used in light reaction to
generate NADPH + H+ and ATP.
1. The immediate donor of hydrogen in dark reaction is
1) NADPH + H+
2) H2O
3)NADH + H+
4) CO2
2. The ultimate donor of hydrogen in plant photosynthesis is
3) NADPH + H +
4) Light
1) CO2
2) H2O
3. What is the first aldehydic sugar formed in photosynthesis ?
l) PGAL
2) Glucose
3) Fructose-1,6-P
4) DHAP
4. Some reactions of Calvin cycle are the reverse of which other metabolic pathway ?
1) Glycolysis
2) CAM
4) Krebs cycle
3) C4
1) 1
2) 2
PHOTOSYNTHESIS
3) 1
4) 1
5) 2
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PHOTOSYNTHESIS INTRODUCTIONAND EARLY EXPERIMENTS
1. Oxygen which is liberated during photosynthesis comes from 1) Carbon dioxide
2) Water
3) Chlorophyll
4) Phosphoglycericacid
2. In which of the following process, the light energy is converted into chemical energy?
1) Digestive action
2) Respiration
3) Photosynthesis
4) Fermentation
3. During photosynthesis the oxygen in glucose comes from
1) Water
2) Carbon dioxide
3) Both from water and CO2 4) O2 in air
4. The law of limiting factor for photosynthesis was given by
1) R. Hill
2) Krebs
3) Calvin
4) Blackman
5. The percentage of light energy utilized by higher plants, in the process of photosynthesis is
1) 100%
2) 10%
3) 50%
4) 1-2%
6. If the CO2 content of the atmosphere is as high as 300 parts per million 1) All plants would be killed
2) The plants would not grow properly
3) Plants would grow for some time and then die 4) The plants would thrive well
7. The isotope of carbon used extensively for studies in photosynthesis
1) C13
2) C14
3) C15
4) C16
8. Which is the evidence to show that oxygen released in photosynthesis comes from water?
1) Isotopic oxygen(O18) suppplied as H2O appears in the O 2 released in photosynthesis
2) Activated chloroplast in water released O2 if supplied potssium ferrocyanide or some other reducing agent
in the absence of CO2
3) Photosynthetic bacteria use H2S and CO2 to make carbohydrates, H2O and sulphur
4) All of the above
9. The path of CO2 in the dark reactions of photosynthesis was sucessfully traced by the use of the
following
1) O218
2) C14O2
3) P32
4) X-rays
10. Discovery of Emerson effect has already shown the existence of
1) Two distinct photosystems
2) Light and dark reactions of photosynthesis
3) Photophosphorylation
4) Photorespiration
11. Name the scientist, who first pointed out that plants purify foul air by bell jar experiment?
1) Willstatter
2) Robert Hooke
3) Priestley
4) Jean Senebier
12. Of thetotal amount of water absorbed by the plant, its actual percentage usedduring photosynthesis is
1) 50%
2) 90%
3) 1%
4) 25%
13. Moll's half leaf experiment explains that
1) Carbon dioxide is essential for photosynthesis
2) Chlorophyll and water are necessaryfor photosynthesis
3) Light and water are essential for photosynthesis
4) All the above are correct
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14. Oxygen during photosynthesis comes from water was proved with the help of O18 experiment by
1) Ruben and Kamen
2) Hill
3) Warburg
4) Blackman
15. Name of the scientist who pointed out the importance of different wavelengths of light using a
green algae and aerobic bacteria
1) Priestley
2) Ingen-Housz
3) K.V. Thimann
4) Englemann
16. Conversion of light energy into chemical energy within the plant body was first stated by ?
1) Mayer and Anderson 2) Calvin
3) Robert Mayer
4) Willstatter and Stoll
17. Photosynthesis is
1) Oxidative,exergonic, catabolic
2) Redox-reaction, endergonic, anabolic
3) Reductive,exergonic, anabolic
4) Reductive, endergonic, catabolic
18. The significance of light & chlorophyll in photosynthesis was discovered by
1) Priestley
2) Ingenhousz
3) Englemann
4) Blackman
19. Wavelength of light responsible for Emerson's enhancement effect
2) only 680 nm  
4) Both 680 nm  and 680 nm 
1) only 680 nm 
3) infrared wavelength
PHOTOSYNTHETICAPPARATUS, PIGMENTS & PIGMENT SYSTEMS
20. The process of photo-phosphorylation take place in
1) Chloroplast
2) Ribosomes
3) Mitochondria
4) Cell-wall
21. PS I occurs in
1) Appressed part of granal thylakoids
2) Appressed and non appressed part of grana thylakoids
3) Stroma
4) Stroma thylakoids and non-appressed part of grana thylakoids.
22. Which one of the following pigment does not occur in the chloroplast?
1) Carotene
2) Xanthophyll
3) Chlorophyll 'b'
4)Anthocyanin
2) Mg
3) K
4) Mn
3)Anthocyanin
4) Xanthophyll
3) Intergrana
4) Mitochondria
23. Chlorophyll contains
1) Fe
24. Which pigment is water soluble?
1) Chlorophyll
2) Carotene
25. The site for dark reaction of photosynthesis is
1) Stroma
2) Grana
26. Chlorophyll is present
1) In the grana of chloroplasts
2) On the surface of chloroplasts
3) Dispersed through out the chloroplasts
4) In the stroma of chloroplasts
27. Which colour of light gives maximum absorption peak by chlorophyll 'a' ?
1) Blue light
PHOTOSYNTHESIS
2) Green light
3) Violet light
73
4) Red light
Sr|12th NEET|BOTANY:VOL-II
28. Presence of carotenes in chloroplast helps in
1) ATP synthesis
2) Transferring radiant energyinto chemical energy
3) Protectingchlorophyllmolecules from photooxidation
4) Absorption of longer wavelength of light
29. The formula of chlorophyll 'a' is
30.
31.
32.
33.
34.
35.
36.
37.
38.
4) C5lH70O6N4 Mg
1) C35H72O5N4 Mg
2) C55H70O3N4Mg
3) C55H72O5N4 Mg
The number of pigment molecules in quantasome is:
1) 250 - 400
2) 300 - 900
3) 500 - 600
4) 50 -100
The main difference between chlorophyll 'a' and 'b' is:
1) Chlorophyll 'a' is a linear chain compound and 'b' is branched chain
2) Chlorophyll 'a' has no Mg+ ion in center of molecule
3) In chlorophyll 'a' there is -CH3 group whereas in 'b' it is -CHO group
4) All of the above
Chlorophyll 'a' is found in
1) All O2 releasing photosynthetic forms
2)Onlyhigher plants.
3) Higher plants that photosynthesize
4) All photosynthetic eukaryotes.
In pigment system-I, reaction centre is
1) P-600
2) P-680
3) P-700
4) P-720
Basic structure of all chlorophyll comprises of
1) Cytochrome system
2) Flavoproteins
3) Porphyrin system
4) Plastocyanin
What is the by product of bacterial photosynthesis?
1) O2
2) CO2
3) S
4) H2S
In chlorophyll molecule "Mg" is situated in
1) Centre of porphyrin ring
2) Corner of porphyrin
3) Inphytol tail
4) In isocyclic ring
The photosynthetic pigment "chlorophylls" are soluble in
1) Water
2) Inorganic solvent
3) Water & organic solvent 4) Organicsolvent
Which of the following chlorophyll is lack of phytol- tail?
1) Chl.'a'
2) Chl. 'b'
3) Chl.'c'
4) Chl.'e'
39. Which of the following protein is most abundant on the earth?
1) Catalase
2) Rubisco
3) Amylase
4) None of these
40. Universal photosynthetic chlorophyll is
1) Chl.'a'
2) Chl. 'b'
3)Chl.'c'
4) Chl.'e'
41. Which of the following is the site of photolysis of water ?
1) Stroma of chloroplast2) Cristae of chloroplast
3) Ribosomeof chloroplast
4) Lumen surface of thylakoid membrane
42. Which one of the following is precursor of protochlorophyll?
1) Acetyl CO A
2) Succinyl COA
3) Oxlaoacetic acid
4)  -ketoglutarate
74
PHOTOSYNTHESIS
Sr|12th NEET|BOTANY:VOL-II
LIGHT REACTIONS OR PHOTOPHOSPHORYLATION
43. The first step in photosynthesis is
1) Joining of three carbon atoms to from glucose
2) Formation of ATP
3) Ionization of water
4) Excitement of an electron of chlorophyll bya photon of light
44. The gain of light reaction is
1) ATP & NADPH2
2) NADPH2 & glucose (3) OnlyATP
4) O2 & glucose
45. Algae and other submerged plants bount in water during day time and sink at night, because
1) They come up to receive O2
2) They lose weight at night
3) They become bouyant due to accumulation of O2 as a result of photosynthesis
4) Theybecome light due to food material accumulation
46. Which one of the following concerns with photophosphorylation
ightenergy
1) ADP + AMP l

 ATP
47.
48.
49.
50.
51.
52.
53.
54.
55.
ightenergy
2) ADP + Inorganic PO4 l

 ATP
3) ADP + Inorganic PO4  ATP
4) AMP + Inorganic PO4 ATP
The function of ATP in photosynthesis is the transfer of energy from the
1) Dark reaction to the light reaction
2) Light reaction to the dark reaction
3) Chloroplaststo mitochondria
4) Mitochondria to chloroplasts
In photosynthesis, hydrogen is transferred from the light reactions to dark reactions by
1) DPN
2) DNA
3) ATP
4) NADP
During photochemical reaction of photosynthesis 1) liberation of O2 takes place
2) Formation of ATP and NADPH2 take place
3) Liberation of O2, formation of ATP, and NADPH2 takes place
4) Assimilation of CO2 takes place
ADP + iP= ATPin grana is called
1) Phosphorylation
2) Oxidativephosphorylation
3) Photophosphorylation
4) Photolysis
Which of the following is excited molecule during photosynthesis
1) Chlorophyll
2) Oxygen
3) Carbondioxide
NADPH2 is also called
1) Real power
2) Oxidisingagent
3) Power house of energy
4) Reducing power
During ionisation of H2O, H+ is ultimately captured by
2) NADP
1) Chlorophyll
3) O2
At the time of ionization of H2O, which initially captures the electron
1) Chlorophyll
2) NADP
3) OHIn cyclic photophosphorylation which one of the following is formed
4) Water
1) NADP & ATP
4) NADH2 and O2
PHOTOSYNTHESIS
2) ATP
3) NADPH2, ATP and O2
75
4) Cytochrome
4) Cytochrome
Sr|12th NEET|BOTANY:VOL-II
56. Fixation of 1 C02 requires
2) 2NADP.H2 & 3ATP
1) 6NADP.H2 & 3ATP
4) 5 NADP.H2 & 3ATP
3) 4 NADP.H2 & 3ATP
57. Photooxidation of water in photosynthesis is in association of
1) Cytochrome b6
2) Pigment system -1
3) Pigment system - II
4) Plastocyanin
58. During ATPsynthesis electron pass through
1) Water
2) Cytochromes
3) O2
4) CO2
59. Which pigment system immediately donates e- for the reduction of NADP.
1) PS II
2) PS I
4) Plastoquinone
3) CO2
60. Photosynthesis is an oxidation reduction process, the materials that is oxidised is
1) CO2
2) NADP
61. Photo - oxidation of chlorophyll is called
1) Intensification
2) Chlorosis
3) H2O
3) Solarization
62. The electron ejected by P680 in light reaction is initially accepted by
1) Plastoquinone
2) ATP
3) Ferredoxin
63. Which element are presents in OEC (Oxygen evolving complex)
1) Mn++
2) Cl3) Ca++
64. Which one is Cu++ containing protein complex
1) Ferridoxin
2) Plastocyanin
3) Plastoquinone
65. Only pigment system-I is concerned with
1) Photolysis of H2O
3) Non-cyclic photophosphorylation
4) PGA
4) Defoliation
4) P-700
4)All
4) Cytochrome
2)Cyclic photophosphorylation
4) Oxidativephosphorylation
66. The first electron carrier molecule for e- excited from P700 is
1) Cytochrome
2) Cu protein/Plastocyanin
3) FeS protein/Ferredoxin
4) Fe-Mg protein
67. Pigment system-II occurs in
1) Grana
2) Stroma
3) Matrix
68. During photosynthesis
4) Oxysomes
1) Water is reduced & CO2 is oxidized
2) CO2 is reduced & water is oxidized
3) Both CO2 & water get reduced
4) Both CO2 & water get oxidized
69. Connecting link between light phase and dark phase of photosynthesis.
1) OnlyATP
2) Only NADH2
3) Only NADPH2
4) ATP and NADPH2
70. Which photosynthetic pigment converts nascent oxygen to molecular oxygen
1) Chlorophyll-a
2) Carotenoids
3) Phycobilins
4) Chlorophyll-b
71. Hill reaction occurs in
1) High altitude plants
2) Total darkness
4) Absence of water
3) Presence of ferricyanide
DARK REACTIONS (C3-PLANTS, C4-PLANTS, CAM-PLANTS)
72. In photosynthesis CO2 combines with
1) RUBP
2) ATP
3) ADP
76
4) PGA
PHOTOSYNTHESIS
Sr|12th NEET|BOTANY:VOL-II
73. During the dark reactions of photosynthesis
1) Water splits
2) CO2 is reduced to organic compounds
3) Chlorophyllis activated
4) Stable C6-sugar is broken into three carbon sugars
74. Carbohydrates, the most abundant biomolecules on earth, are produced by :
1) all bacteria, fungi and algae
2) fungi, algae and green plant cells
3) some bacteria, algae and green plants cells
4) viruses, fungi and bacteria
7 5. The enzyme that fixes atmospheric CO2 in C4 plants is
1) PEP carboxylase
2) Hexokinase
3) RUBP oxygenase
4) Hydrogenase
76. During photosynthesis when PGA is changed into phosphoglyceraldehyde which of the following
reaction occur
77.
78.
79.
80.
81.
82.
83.
84.
1) Oxidation
2) Reduction
3) Electrolysis
4) Hydrolysis
Carbon refixation in C4 plants occurs in chloroplasts of
1) Palisade tissue
2) Spongy Mesophyll
3) Bundle sheath cells
4) Gaurd cells
Tropical plants like sugarcane show high efficiency of CO2 fixation because of
1) Calvin cycle
2) Hatch - Slack cycle
3) Cyclic photophosphorylation
4) TCA Cycle
"Kranz" type of Anatomy is found in
1) C4 plant
2) C3 plant
3) Succulent plants
4) None of the above
Ribulosediphosphate carboxylase enzyme, catalyse the carboxylation reaction between
1) CO2 and ribulose-1, 5-diphosphate
2) Oxaloacetic acid and acetyl Co-A
3) PGA and dihydroxyacetone phosphate
4) Ribulosediphosphate and phosphate glyceraldehyde
Which of the following is C-4 plants
1) Maize
2)Atriplex
3) Sugarcane
4) All of the above
C4 plants are adapted to
1) Hot and dry climate 2) Temperate climate
3) Cold and dry climate
4) Hotand Humidclimate
C4 plants are found among
1) Onlygramineae
2) Onlymonocot
3) Only dicot
4) Monocots as well as dicots
In case of C4 pathway, the first step is
1) CO2 combines with RUDP
2) CO2 combines with PGA
3) CO2 combines with PEP
4) CO2 combines with RMP
85. In dark reaction, first reaction is the
1) Carboxylation
2) Decarboxylation
3) Dehydrogenation
4) Deamination
86. Number of ATPmolecules requried for regeneration phase of RUBP during synthesis of 1 glucose
molecule.
1) 6
2) 12
3) 18
4) 30
87. Isotopes employed to study the process of photosynthesis reaction.
1) S35 and P32
2) C14 and O18
3) N14 and Co60
4) N14 and O18
88. Chloroplast is present in bundle sheath cells of
3) CAM plants
4) Photorespiringplants
1) C3 - plants
2) C4 plants
PHOTOSYNTHESIS
77
Sr|12th NEET|BOTANY:VOL-II
89. CO2 ir accepted by RUBP in C4 plants in
1) Mesophyll cells
2) Bundle sheath cells
90. Bundle sheath chloroplast of C4 plant are
1) Large & agranal
2) Large & granal
3) Stomatal gaurd cells
4)Epidermal cells
3) Small & agranal
4) Small & granal
91. Most efficient photosynthesis & presence of bundle sheath chloroplast are characteristics of
4) CAM plants
1) C3 plants
2) C2 plants
3) C4 plants
92. In C4 pathway the fixation of CO2 (by PEPCase) occurs in
1) Palisade tissue
2) Mesophyll
3) Bundle sheath
4) Gaurd cell
93. Synthesis of fructose in C4 pathway occurs in the chloroplast of
1) Spongymesophyll 2) Bundle sheath cells
3) Gaurd cells
4) Palisadetissue
94. In addition to the 12 molecules of NADP.H2 the energy required for the synthesis of one mole of
hexose by C3 and C4 pathway is
1) 18 molecules of ATP
2) 30 molecules of ATP
3) 18 & 30 molecules of ATP respectively
4) 30 & 18 molecules of ATP respectively
95. How many molecules of water are needed by a green plant to produce one molecule of hexose/
reduce 6 molecules of CO2
1) 6
2) 12
3) 24
4) Only one
96. How many Calvin cycles would generate one molecules of glucose/hexose
1) One cycle
2) Three cycles
3) Six cycles
4) Twelvecycles
97. CAM - plants are mainly
1) Succulent xerophyte 2) Hydrophytes
3) Epiphytes
4) None of the above
98. The first stable product of Calvin cycle and HSK- cycle are
1) 4-C and 3-C compounds
2) 4-C and 6-C compounds
3) 3-C and 4-C compounds
4) 5-C and 4 - C compounds
99. Which of the following was used during discovery of Calvin cycle :
1) Spirogyra
2) Volvox
3) Chlamydomonas
4) Chlorella
100. In sugarcane plant 14CO2 is fixed in malic acid, in which the enzyme that fixes CO2 is
1) Ribulose biphosphate carboxylase
2) Phosphoenol pyruvic acid carboxylase (PEP-case)
3) Ribulosephosphate kinase
4) Fructose phosphatase
PHOTORESPIRATION, BACTERIALPHOTOSYNTHESIS & FACTORS SPE OFNUTRITION
IN PLANTS
101. The rate of photosynthesis does not depend upon
1) Light duration
2) Light intensity
3) Light quality(colour)
4) Temperature
102. Which one of the following have high CO2 compensation point
4) Alpine herbs
1) C2 plants
2) C3 plants
3) C4 plants
103. Solarisation is a process in which
1) Sugar are formed with the help of solar energy 2) Chlorophyll is formed
3)Destruction of chlorophyll
4) Mobilizationof light energy
78
PHOTOSYNTHESIS
Sr|12th NEET|BOTANY:VOL-II
104. Accumulation of food in assimilatory cells results in
1) Increase in the rate of photosynthesis
2) Decrease in the rate of photosynthesis
3) No effect
4) May increase or decrease
105. As compared to a C3-plant how many additional molecules of ATPare needed for net production of
one molecule of hexose sugar by C4-plants :
1) two
2) six
3) zero
4) twelve
106. First stable product of Photorespiration is
1) PGAL
2) Glycerate
3) Glycine
4) Phosphoglycolate
107. Etiolated plants are formed due to lack of
1) Light
2) Hg
3) Fe
4) Mg
108. During day light hours, the rate of photosynthesis is higher than that of respiration and the ratio of
oxygen produced to that of consumed is
1) 10 : 1
2) 5 : 1
3) 1 : 1
4) 50 : 1
109. Generally atmospheric CO2 is not limiting for hydrophytes
1) Mesophytes plants fix H2S in their photosynthesis
2) These plants obtain CO2 from water in the form of HCO33) Glucose is not required for their respiration
4) All the above
110. Photorespiration is favoured by
1) Low light intensity 2) Low O2 and high CO2 3) Low temperature
4) High O2 and Low CO2
111. What is C2 - Cycle
1) Glycolate cycle
2) Calvin cycle
3) Kreb's cycle
4) TCA - cycle
112. Compensation point means
1) When the rate of photosynthesis is equal to rate of respiration
2) When there is neither photosynthesis nor respiration
3) When theentire food manufactured in photosynthesis remains unutilized
4) When availabilityof water equalise with necessityof water.
113. At the compensation point there will not be
1) Photosynthesis
2) Net gaseous exchange between the plant and its environment
3) Respiration in plants
4) Loss in weight of the plant in dark
114. What does not occur in photorespiration
1) Utilization of O2
2) Production of CO2
3) Synthesis of ATP
4) All the above
115. DCMU is an inhibitor of
1) PS-I
2) PS-II
3) Calvin cycle
4) Kreb's cycle
116. Main factor which limits the rate of photosynthesis on a clear day is
1) Chlorophyll
2) Light
3) CO2
4) Water
117. Photosynthetic bacteria differ from green plants in
1) Nature of their photosynthetic pigments
2) Type of electron donors
3) Photosynthetic process being non oxygenic
4) All of the above
PHOTOSYNTHESIS
79
Sr|12th NEET|BOTANY:VOL-II
118. Which one of the following is wrong in relation to photorespiration
1) It occurs in chloroplasts
2) It occurs in daytime only
3) It is a characterisitic of C4 plants
4) It is a characteristic of C3 plants
119. Photosynthetically active radiation (PAR) represents the following range of wavelength
1) 400-700 nm
2) 500-600 nm
3) 450-950 nm
4) 340-450 nm
120. In C3 plants, the first stable product of photosynthesis during the dark reaction is
1) Phosphoglycereldehyde
2) Malic acid
3) Oxaloacetic acid
4) 3-phosphoglyceric acid
121. Plants adapted to low light intensity have
1) Leaves modified to spines
2) Large photosynthetic unit size than the sun plants
3) Higher rate of CO2 fixation than the sun plants 4) More extended root system
122. In chloroplasts, chlorophyll is present in the
1) Stroma
2) Outer membrane
3) Inner membrane
4) Thylakoids
123. Which one of the following categories of organisms do not evolve oxygen during photosynthesis
1) Red algae
2) Photosyntheticbacteria
3) C4-plants with Kranz anatomy
4) Blue green algae
124. Which pair is wrong
1) C3 plant-maize
2) Calvin cycle-PGA
3) Hatch anti Slack cycle - Maize
4) C4-plant- Kranz Anatomy
125. Photosynthesis in C4 plants is relatively less limited by atmospheric CO2 levels because :
1) Four carbon acids are the primary initial CO2 fixation products
2) The primaryfixation of CO2 is mediated via PEP carboxylase
3) Effective pumping of CO2 into bundlesheath cells
4) Rubisco in C4 plants has higher affinity for CO2
1) 2
11) 3
21) 4
31) 3
41) 4
51) 1
61) 3
71) 3
81) 4
91) 3
101) 1
111) 1
121) 2
2) 3
12) 3
22) 4
32) 1
42) 2
52) 4
62) 1
72) 1
82) 1
92) 2
102) 2
112) 1
122) 4
3) 2
13) 1
23) 2
33) 3
43) 4
53) 2
63) 4
73) 2
83) 4
93) 2
103) 3
113) 2
123) 2
4) 4
14) 1
24) 3
34) 3
44) 1
54) 1
64) 2
74) 3
84) 3
94) 3
104) 2
114) 3
124) 1
5) 4
15) 4
25) 1
35) 3
45) 3
55) 2
65) 2
75) 1
85) 1
95) 2
105) 4
115) 2
125) 3
6) 4
16) 3
26) 1
36) 4
46) 2
56) 2
66) 3
76) 2
86) 1
96) 3
106) 4
116) 3
80
7) 2
17) 2
27) 1
37) 3
47) 2
57) 3
67) 1
77) 3
87) 2
97) 1
107) 1
117) 4
8) 4
18) 2
28) 3
38) 4
48) 4
58) 2
68) 2
78) 2
88) 2
98) 3
108) 1
118) 3
9) 2
19) 4
29) 3
39) 2
49) 3
59) 2
69) 4
79) 1
89) 2
99) 4
109) 2
119) 1
10) 1
20) 1
30) 1
40) 1
50) 3
60) 3
70) 2
80) 1
90) 1
100) 2
110) 4
120) 4
PHOTOSYNTHESIS
Sr|12th NEET|BOTANY:VOL-II
AIPMT 2006
1. In photosystem-I, the first electron acceptor is
1) Plastocyanin
2)An iron-sulphur protein
3) Ferredoxin
4) Cytochrome
2. During photorespiration, the oxygen consuming reaction(s) occur in
1) Grana of chloroplasts and peroxisomes
3) Stroma of chloroplasts and mitochondria
2) Stroma of chloroplasts
4) Stroma of chloroplasts and peroxisomes
AIPMT 2007
3. The first acceptor of electrons from an excited chlorophyll molecule of photosystem II is
1) Quinone
2) Cytochrome
3) Iron-sulphur protein
4) Ferredoxin
4. In the leaves of C4 plants, malic acid formation during CO2 fixation occurs in the cells of
1) Epidermis
2) Mesophyll
3) Bundle Sheath
4) Phloem
AIPMT 2008
5. In leaves of C4 plants malic acid synthesis during CO2 fixation occurs in
1) Bundle sheath
2) Guard cells
3) Epidermal cells
4) Mesophyll cells
6. The C4 plants are photosynthetically more efficient than C3 plants because
1) The CO2 efflux is not prevented
2) They have more chloroplasts
3) The CO2 compensation point is more
4) CO2 generated during photorespiration is trapped and recycled through PEP carboxylase
7. Electrons from excited chlorophyll molecule of photosystem II are accepted first by
1) Quinone
2) Ferredoxin
3) Cytochrome-b
4) Cytochrome-f
3) Chbrobium
4) Chromatium
AIPMT 2009
8. Oxygenic photosynthesis occurs in
1) Oscillatoria
2) Rhodospirillum
9. Cyclic photophosphorylation results in the formation of
1) ATP and NADPH
4) NADPH
2) ATP, NADPH and O2 3) ATP
AIPMT-Pre 2010
10. PGA as the first CO2 fixation product was discovered in photosynthesis of :
1) Bryophyte
PHOTOSYNTHESIS
2) Gymnosperm
3)Angiosperm
81
4)Alga
Sr|12th NEET|BOTANY:VOL-II
11. C4 plants are more efficient in photosynthesis than C3 plants due to :
1) Higher leaf area
2) Presence of larger number of choloplasts in the leaf cells
3) Presence of thin cuticle
4) Lower rate of photorespiration
12. Study the pathway given below.
Atmospheric CO 2
Plasma membrane
Mesophyll
cell
Cell wall
HCO3-Phosphoenolpyruvate
(3C)
2ATP
A
C
OAA (C4acid)
NADP
NADPH
PEP(C3 acid)
Malic/Aspartic acid(C 4 acid)
Bundle
sheath
cell
Transport
Transport
Fixation by
Calvin Cycle
Malic/Aspartic acid
(C4 acid)
CO2
Pyruvic acid (C 3 acid)
B
In which of the following options correct words for all the three blanks A, B and C are indicated ?
1) A-Fixation B-Transamination C-Regeneration
2) A-Fixation B-Decarboxylation C-Regeneration
3) A-Carboxylation B-Decarboxylation C-Reduction
4) A-Decarboxylation B-Reduction C-Regeneration
13. Read the following four statements, A, B, C and D and select the right option having both correct
statements.
Statements :
A) Z scheme of light reaction takes place in present of PSI only.
B) Only PSI is functional in cyclic photophosphorylation
C) Cyclic photophosphorylation results into synthesis ofATP and NADPH2
D) Stroma lamellae lack PSII as well as NADP
Options :
82
PHOTOSYNTHESIS
Sr|12th NEET|BOTANY:VOL-II
1) A and B
2) B and C
3) C and D
4) B and D
3) Disease resistance
4) Reproduction
AIPMT-Pre 2011
14. CAM helps the plants in
1) Conserving water
2) Secondary growth
AIPMT-Mains 2011
15. In Kranz anatomy, the bundle sheath cells have:
1) thick walls, manyintercellular spaces and few chloroplasts
2) thin walls, manyintercellular spaces and no chloroplasts.
3) thick walls, no intercellular spaces and large number of chloroplasts.
4) thin walls, no intercellular spaces and several chloroplasts.
AIPMT-Pre 2012
16. A process that makes important difference between C3 and C4 plants is
1) Photosynthesis
2) Photorespiration
3) Transpiration
4) Glycolysis
17. The correct sequence of cell organelles during photorespiration is
1) Chloroplast-mitochondria-peroxisome
2) Chloroplast-vacuole-peroxisome
3) Chloroplast-Golgibodies-mitochondria
4) Chloroplast-Rough endoplasmic reticulum- Dictyosomes
AIPMT 2014
18. Anoxygenic photosynthesis is characteristic of
1) Rhodospirillum
2) Spirogyra
3) Chlamydomonas
4) Ulva
3) Growth
4) Movement
Re-AIPMT 2015
19. Chromatophores take part in :
1) Respiration
2) Photosynthesis
20. In photosynthesis, the light-independent reactions take place at :
1)Stromal matrix
2) Thylakoid lumen
3) Photosystem - I
4) Photosystem-II
NEET-I 2016
21. Emerson's enhancement effect and Red drop have been instrumental in the discovery of
1) Photophosphorylation and non-cyclic electron transport
2) Two photosystems operating simultaneously
3) Photophosphorylation and cyclic electron transport
4) Oxidative phosphorylation
22. In a chloroplast the highest number of protons are found in :PHOTOSYNTHESIS
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Sr|12th NEET|BOTANY:VOL-II
1) Stroma
2) Lumen of thylakoids
3) Inter membrane space
4)Antennae complex
23. A plant in your garden avoids photorespiratory losses, has improved water use efficiency shows
high rates of photosynthesis at high temperatures and has improved efficiency of nitrogen utilisation.
In which of the following physiological groups wouldyou assign this plant ?
1) C3
3) CAM
2) C4
4) Nitrogen fixer
NEET -II 2016
24. The process which makes major difference between C3 and C4 plants is
1) Calvin Cycle
2) photorespiration
3) respiration
4) Glycolysis
25. Oxidative phosphorylation is
1) Formation of ATP by transfer of phosphate group from a substrate to ADP
2) Oxidation of phosphate group in ATP
3) Addition of phosphate group to ATP
4) Formation of ATP by energyreleased from electrons removed during substrate
NEET 2017
26. With reference to factors affecting the rate of photosynthesis, which of the following statements is
not correct ?
1) Increasing atmospheric CO2 concentration upto 0.05% can enhance CO2 fixation rate
2) C3 plants respond to higher temperature with enhanced photosynthesis while C4 plants have much lower
temperature optimum
3) Tomato is a green house crop which can be grown in CO2 enriched atmosphere for higher yield
4) Light satureation for CO2 fixation occurs at 10% of full sunlight
27. Phosphoenol pyruvate (PEP) is the primary CO2 acceptor in
1) C4 plants
2) C2 plants
3) C3 and C4 plants
4) C3 plants
1) 2
2) 1
3) 4
4) 2
5) 4
6) 2
7) 1
8) 1
9) 3
10) 4
11) 2
12) 2
13) 4
14) 1
15) 3
16) 2
17) 1
18) 1
19) 2
20) 1
21) 2
22) 2
23) 2
24) 2
25) 2
26) 2
27) 1
1. "Only green part of the plants could release oxygen" this is shown by 1) Priestley
2) Moll
3) Ingenhousz
3) Julius Van Sachs
2. In Calvin cycle which step involve utilisation of 2 molecules of ATP for phosphorylation and two of
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NADPH2 per CO2 molecule fixed ?
1) Regeneration
2) Carboxylation
3) Reduction
4) All of above
3. Which character make C4 plants special ?
1) Special type of leaf anatomy
2) They can tolerate high temperature
3) Show response to high light intensities
4) All of the above
4. Most abundant enzyme in the world is
1) Collagen
2) RubisCO
3) PEPcase
4) Pyruvate dikinase
5. PS-II is physically located on
1) Inner side of the membrane of the thylakoid
2) Outer side of the membrane of the thylakoid
3) Middle of the membrane of the thylakoid
4) None of the above
6. For every CO2molecule entering the Calvin cycle, required energy is
1) 3 ATP and 2 NADPH
2) 2 ATP and 3 NADPH
3) 3 ATP and 3 NADPH
4) 2 ATP and 2 NADPH
7. In C4 plants, bundle sheath cell are characterised by
1) Large number of chloroplasts
2) Thick walls impervious to gaseous exchange
3) No intercellular spaces
4) All the above
8. Which enzyme is absent in mesophyll cells of C4 plants ?
1) RubisCO
2) PEPcase
3) Both (1) and (2)
4) None of the above
9. In C4 plants photorespiration does not occur, due to: 1) Presence of RubisCO enzyme
2) Presence of high light intensity
3) Increased concentration of CO2 at RuBisCO enzyme site
4) Presence of bundle sheath cells.
10. In photosynthesis during ATP formation accumulation of protons occurs
1) in lumen of thylakoid
2) in stroma of chloroplast
3) in stroma lamellae
4) at outer surface of thylakoid
11. By using the bell jar, which of the following showed that sunlight is essential to plant process that
purifies the air?
1) Joseph priestley
2) Julius Von Sachs
3) T.W. Engelmann
4) Jan Ingenhousz
12. Radioisotopic technique was used to prove some facts about
1) light reactionof photosynthesis
2) biosynthetic phase of photosynthesis
3) Both (1) and (2)
4) Different shapes of chloroplasts in plants
13. For the synthesis of one molecule of sucrose, how may ATP molecules are required in reduction
step of Calvin cycle?
PHOTOSYNTHESIS
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1) 24 ATP
2) 18 ATP
3) 2 ATP
4) 12 ATP
14. The plants with Hatch and Slack pathway are adapted to
1) humid temperate regions
2) dry temperate regions
3) humid tropical regions
4) drytropical regions
15. C3 plants have been used as greenhouse crops for higher yields because
1) These plants show CO2 saturation at about 360  IL-l
2) Current availability of CO2 levels is limiting to C3 plants
3) These plants are photosyntheticallymore efficient than C4 plants
4) C3 plants loses less water as compare to C4 plants
16. Word dark reaction for biosynthetic phase of photosynthesis is misnomer word because
1) Dark reaction occur during dark
2) Dark reaction occur during day
3) Dark reaction is completelyfree from light
4) Dark reaction occur during short dark intervals
17. Fhotosynthetic photosystem is consist of
1) Reaction centre only
2) LHC only
3) Both LHC & reaction centre
4) LHC, reaction centre and ETC
18. In grana lamellae, presence of which of the following specify that ‘z’ scheme found only in grana
lamellae?
1) PS-I, PS-II
2) PS-II & NADP reductase
3) Presence of PS-I & NADP reductase
4) Presence of Mg++ in lumen
19. Which of the following is not needed for photophosphorylation?
1) Photon
2) Proton pump-Co-Q
3) Membrane
4) Proton gradient
20. At higher light intensities gradually rate of photosynthesis
1) Further increases
2) Further decreases
3) Does not show further increase
4) First decreases then increases
21. An elegant experiment with an aquatic plant showed that in bright sunlight, small bubbles were
formed around the green parts while in the dark they did not. It was done by
1) Jan Ingenhousz
2) Van Sachs
3) Priestley
4) Van Niel
22. Based on his studies of purple & green bacteria who demonstrated that photosynthesis is essentially a light dependent reaction in which hydrogen from a suitable oxidisable compound reduces
CO2 to carbohydrates?
1) Van Niel
2) Von Sachs
3) Calvin
4) Priestley
23. Which of following is correct about dark reaction?
1) It is not directly light driven but are dependent on products of light reaction (ATP & NADPH)
2) It occurs in stroma of chloroplast by enzymatic reaction
3) Both
4) None of above
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24. Which of the following is most crucial step of Calvin cycle?
1) Carboxylation
2) Reduction
3) Regeneration
4) None
25. How many ATPare required for regeneration of RUBP in one Calvin cycle.
1) 6 ATP
2) 1 ATP
3) 3 ATP
4) 12 ATP
26. How much energy in terms of ATPequivalents is consumed in the photosynthetic production of a
mole of hexose
1) 36 ATP eq.
2) 38 ATP eq.
3) 40 ATP eq.
4) 54 ATP eq.
27. Glycolate accumulates in chloroplast at
1) Low temp.
2) Low CO2
3)Visiblelight illumination
4) High CO2
28. Represented below is the graph showing action spectrum of photosynthesis superimposed on absorption spectrum of chlorophyll 'a'. Which one of the following is correct for this ?
1) There is a complete one to one overlap between the absorption and action spectrum
2) Bythis overlapping it can be concluded that chlorophyll 'a' is the chief pigment of photosynthesis
3) This overlapping shows that onlychlorophyl 'a' absorb the entire light energy
4) These graphs show that photosynthesis occurs only in the wavelengths of blue and red light
29. Which of the following is the product of oxidation during photosynthesis ?
1) Carbondioxide
2) Glucose
3) Water
4) Oxygen
30. Find out the correct match from the following table
Column-I
Column-II
Column-III
i) Photochemical phase
ii) Paper Chromatography
Photosystem II
Chlorophyll 'b'
Oxygen release
iii) Carotenoids
Chief pigment
Red light absorption
1) (i) only
2) (i) and (ii)
Yellow orange
3)(iii) only
4) (ii) and (iii)
31. In CAM plants, photophosphorylation occurs in
1) Bundle sheathcell, during night
2) Mesophyll cell, during daytime
3)Mesophyll cell, duringnight
4) Bundle sheath cell, during daytime
PHOTOSYNTHESIS
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32. In Calvin cycle, CO2 is fused with primary acceptor molecule to form 3C compound phosphoglycerate. If in this reaction CO2 provides one carbon then how many carbons are present in primary
acceptor molecule ?
1) Five carbons
2) Two carbons
3) Six carbons
4) Three carbons
33. In photosynthesis, NADPH + H+ are oxidised in
1) Calvin cycle
2) noncyclicphotophosphorylation
3) cyclic photophosphorylation
4) Z-scheme
34. Enzyme, which can catalyse both carboxylation and oxygenation of RuBP in the chloroplast, is not
found in which of the following cells ?
1) Mesophyll cells of C4 plants
2) Mesophyll cells of C3 plants
3) Mesophyll cells of CAM plants
4) Bundle sheath cells of C4 plants
35. The product of light reaction of photosynthesis, which is not common between cyclic and non cyclic
photophosphorylation and is not utilized in Calvin cycle, is
1) O2
2) ATP
3) NADPH2
4) O2 and ATP
36. During Z-scheme of photosynthesis which of the following not helps in creation of proton gradient?
1) Release of protons in stroma by water splitting 2) Presence of H-carriers in the thylakoid membrane
3) Reduction of NADP+
4) Oxidation of water by photosystem-II
37. "Plants restore to the air whatever breathing animals and burning candles remove". This was
hypothesised by
1) Stephen Hales
2) Jan Ingenhousz
3) Joseph Priestley
4) Ruben and Kamen
3) Pheophytin
4) FRS
38. Primary electron acceptor of P700 is
1) Plastocyanin
2) Plastoquinone
39. Which phase of Calvin cycle does/do not use any energy rich molecule
1) Carboxylation only
2) Carboxylation and reduction
3) Reductionand regeneration
4) Reduction only
40. The C4 plants differ from C3 plants with reference to the
1) Substance that accepts CO2 in carbon assimilation.
2) Type of end product of photosynthesis
3) Number of NADPH2 that are consumed in synthesis of hexose
4) Type of pigments involved in photosynthesis.
41. How many quanta of light are required per NADPH + H+ formation ?
1) 8 quanta
2) 16 quanta
3) 4 quanta
4) 2 quanta
42. The common feature between non-cyclic and cyclic photophosphorylation is
1) Proton gradient formation
2) Release of O2
3) Formation of NADPH + H+
4) Photolysis of water
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43. The second acceptor of CO2 in C4 plants is
1) PEP
2) Malate
3) Aspartate
4) RuBP
44. In C4 plants, RuBisCO is present in
1) Agranal chloroplasts in mesophyll cells
2) Granal chloroplasts in mesophyll cells
3)Agranal Chloroplasts in bundle sheath cells
4) Granal Chloroplasts in bundle sheath cells
45. How many NADPH + H+ are produced in cyclic photophosphorylation per 4e- flow in its ETS.
1) One
2) Two
3) Four
4) Zero
1) 3
2) 3
3) 4
4) 2
5) 1
6) 1
7) 4
8) 1
9) 3
10) 1
11) 4
12) 3
13) 1
14) 4
15) 2
16) 2
17) 3
18) 2
19) 2
20) 3
21) 1
22) 1
23) 3
24) 1
25) 2
26) 4
27) 2
28) 2
29) 4
30) 1
31) 2
32) 1
33) 1
34) 1
35) 1
36) 1
37) 3
38) 4
39) 1
40) 1
41) 3
42) 1
43) 4
44) 3
45) 4
Directions for Assertion & Reason questions
These questions consist of two statements each, printed as Assertion and Reason. While answering these
Questions you are required to choose any one of the following four responses.
A) If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B) If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C) If Assertion is True but the Reason is False.
D) If both Assertion & Reason are false.
1. Assertion : Photosynthesis is a physico-chemical process
Reason : In photosynthesis transfer of light is a physical process, while synthesis of carbohydrate is a chemical process.
1) A
2) B
3) C
4) D
2. Assertion : In photosynthesis there is synthesis of glucose but it is stored in form of starch.
Reason : Glucose is osmoticallyactive while starch is osmoticallyinactive
1) A
2) B
3) C
4) D
3. Assertion : Photosynthesis is the uphill process, while respiration is the down hill process.
Reason : In photosynthesis CO2(weak e- acceptor) and in respiration O 2 (strong e - acceptor) are used as
substrate.
1) A
PHOTOSYNTHESIS
2) B
3) C
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Sr|12th NEET|BOTANY:VOL-II
4. Assertion : Biosynthetic phase of photosynthesis is known as dark reaction.
Reason : It takes place in absence of light.
1) A
2) B
3) C
4) D
5. Assertion : Presence of accessory pigments enhances rate of photosynthesis.
Reason : Theyenable a wider range of wavelength of incoming light to be utilised for photosynthesis.
1) A
2) B
3) C
4) D
6. Assertion : Excitement of electron from PS to first e- acceptor is uphill process.
Reason : Redox potential of first e- acceptor is less than the ground state of reaction centre.
1) A
2) B
3) C
4) D
7. Assertion : The whole scheme of transfer of electrons strarting from PS-II to NADP+ is called z-zcheme.
Reason : When all the carriers of this scheme are placed in sequence on a redox potential scale. Theyappear
like Z.
1) A
2) B
3) C
4) D
8. Assertion : Both PS-I and PS-II are located on stroma thylakoid membrane
Reason : Photolysis of water and reduction of NADP+ takes place in stroma site.
1) A
2) B
3) C
4) D
9. Assertion : In Stroma lamellae cyclic photophosphorylalion is the onlymean of ATP synthesis
Reason : In stroma lamellae both PS-II and NADP reductase enzyme are absent.
1) A
2) B
3) C
4) D
10. Assertion : Energy is not required to pump protons from stroma to lumen.
Reason : Movement of protons from stroma to lumen is carried out through facilitated diffusion.
1) A
2) B
3) C
4) D
11. Assertion : Biosynthetic phase of photosynthesis is also termed as dark reaction.
Reason : Biosynthetic phaseis not directlydependenton light but it is supported byproductsof light reactions.
1) A
2) B
3) C
4) D
12. Assertion : In all photosynthetic plants first fixation product during biosynthetic phase of photosynthesis is
PGA.
Reason : PGAis the most stable product and is synthesised from both RuBPand PEP, whenever theyact as
first CO2 accepting substance.
1) A
2) B
3) C
4) D
13. Assertion : Carboxylation is the most crucial step of the Calvin cycle.
Reason : In carboxylation both ATP and reducing power get consumed.
1) A
2) B
14. Assertion : To make one molecule of glucose 6
3) C
4) D
turns of Calvin cycle are required.
Reason : In each turn of Calvin cycle there is fixation of one CO2 only while 6CO2 are required for each
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glucose.
1) A
2) B
3) C
4) D
15. Assertion : C4 pathwaycan not effectively work at low temperature conditions.
Reason : Enzyme PPDK does not effectively work at low temperature.
1) A
2) B
3) C
4) D
16. Assertion : C4 plants can tolerate high light intensities.
Reason : Concentric arrangement of mesophyll leads to minimum surface area so that effect of high light
intensity can be overcome.
1) A
2) B
3) C
4) D
17. Assertion : In C4 plants there is no photorespiration.
Reason : In C4 plants photolysis of H2O and Rubisco activity occurs in different cells.
1) A
2) B
3) C
4) D
18. Assertion : C4 plants show greater productivity of biomass.
Reason : In C4 plants there is no photo respiration and maximum absorption of sunlight.
1) A
2) B
3) C
4) D
19. Assertion : C4 plants can perform better phtosynthesis even in low CO2 level in atmosphere.
Reason : In C4 plants there is efficient pumping of CO2 to bundle sheath cells.
1) A
2) B
3) C
4) D
20. Assertion : In mesophyll cells of C4 plants there is no sugar formation after fixation of CO2.
Reason : In mesophyll cells there is no Rubisco so C3 cycle events can not operate.
1) A
2) B
3) C
4) D
21. Assertion : In C4 plants CO2 always transports to bundle sheath cells from mesophyll cells in the form of
malicacid
Reason : OAA is always reduced into malic acid in C4 plants.
1) A
2) B
3) C
4) D
22. Assertion : C4 plants are less efficient than C3 plants.
Reason : In C4 plants respiration is to provide more number of ATP and NADPH2 for reduction of CO2 in
to glucose and regeneration.
1) A
2) B
3) C
4) D
23. Assertion : The basic pathway that results in formation of sugars, the Calvin path way is common to the C3
and C4 plants.
Reason : C3 path is the only biosynthetic path which yields sugar from CO2.
1) A
2) B
3) C
4) D
24. Assertion : Rubisco show either carboxylation or oxygenation activityat a time.
Reason : Binding of CO2 or O2 is competitive and relative concentration of O2 and CO2 determine which will
bind to the enzyme.
PHOTOSYNTHESIS
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Sr|12th NEET|BOTANY:VOL-II
1) A
2) B
3) C
4) D
25. Assertion : Photorespiration is one of the wasteful processes.
Reason : In Photo respiration there is no synthesis of ATP and NADPH
1) A
2) B
3) C
4) D
26. Assertion : In C4 plants there is no photorespiration.
Reason : Rubisco of C4 plants does not show oxygenation affinity.
1) A
2) B
3) C
4) D
27. Assertion : Photosynthetic productivity of plants is also governed by genetic predisposition.
Reason : C3 or C4 nature of plant is ultimatelycontrolled by genetic constitution of plant.
1) A
2) B
3) C
4) D
28. Assertion : In Aquatic conditions usually CO2 concentration regulates the rate of photosynthesis.
Reason : In Aquatic conditions generally CO2 is available at suboptimal level.
1) A
2) B
3) C
4) D
29. Assertion : In terrestrial conditions CO2 usuallyacts as main determining factor of photosynthesis.
Reason : Usually CO2 is available at sub optimal level in terrestrial conditions.
1) A
2) B
3) C
4) D
30. Assertion : Except sciophyte and plants of dense forest, light is rarely a limiting factor in nature.
Reason : Light saturation occurs at 10 percent of full summer sunlight.
1) A
2) B
3) C
4) D
31. Assertion : In C3 plants increase in CO2 concentration will increase their productivity.
Reason : In C3 plants CO2 saturation point is 450 ppm.
1) A
2) B
3) C
4) D
32. Assertion : Water stress primarily shows indirect effect on photosynthesis.
Reason : Water stress leads to closure of stomata and prevent gaseous exchange.
1) A
2) B
3) C
4) D
33. Assertion : Indirectly water stress leads to decrease in photosynthesis.
Reason : Water stress leads to wilt of leaves and minimise their surface area.
1) A
2) B
3) C
4) D
1) 1
2) 1
3) 1
4) 3
5) 1
6) 1
7) 1
8) 4
9) 1
10) 4
11) 1
12) 4
13) 3
14) 1
15) 1
16) 1
17) 1
18) 1
19) 1
20) 1
21) 4
22) 4
23) 1
24) 1
25) 1
26) 3
27) 1
28) 4
29) 1
30) 1
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PHOTOSYNTHESIS