Photosynthesis in Higher Plants Flashcards
Green plants make their own food by the process of
Photosynthesis
A physicochemical process by which plants use light energy to drive the synthesis of organic compounds is called
Photosynthesis
The process which is primary source of all food on earth is
Photosynthesis
Apart from light and carbon dioxide, which pigment is essential for photosynthesis to occur?
Chlorophyll
A KOH soaked cotton will absorb gaseous _____________
Carbon dioxide
The scientist who in 1770 performed a series of experiments that revealed the essential role of air in the growth of green plants was
Joseph Priestley
Oxygen in 1774 was discovered by
Joseph Priestley
Who showed that sunlight is essential to the plant process?
Jan Ingenhousz
Ingenhousz in his experiment with an aquatic plant showed some bubbles formed around green parts of plant to be composed of
Oxygen
Only the green part of plants could release oxygen was proved by
Jan Ingenhousz
The scientist who provided evidence for production of glucose when plants grow was
Julius von Sachs
The scientist behind the finding that the glucose is made in green parts of plant and is usually stored as starch was
Julius von Sachs
Engelmann observed that bacteria accumulated mainly in region of ___________ and __________ light of split spectrum from his experiments on Cladophora
Blue and red
The first action spectrum of photosynthesis was described by
T. W. Engelmann
Cornelius van Niel based on his studies of purple and green bacteria, demonstrated that photosynthesis is essentially a _____________ reaction
Light dependent
Cornelius in his experiment demonstrated that in a light-dependent reaction, hydrogen from a suitable oxidisable compound reduces carbon dioxide to __________
Carbohydrates
Hydrogen donor for purple and green sulphur bacteria is
H2S
In purple and green sulphur bacteria, oxidation product is
Sulphur or sulphate
Cornelius inferred that oxygen evolved by green plant comes from ___________
Water
The cells of leaves having large number of chloroplasts are
Mesophyll cells
Within the chloroplast there is membranous system consisting of ________, the _________, and the ________ stroma.
Grana, stroma lamellae, matrix
Synthesis of sugar through enzyme reactions and its conversion to starch occurs in
Stroma
Reactions occuring in membrane system are called ___________ reactions
Light
Carbon reactions occuring in stroma are called
Dark reactions
Dark reactions are not directly dependent on light but on the products of light reactions like _______ and _______
ATP and NADPH
Separation of leaf pigments of any green plant can be done by which basic technique?
Paper chromatography
The four pigments giving colour to leaves are
Chlorophyll a, chlorophyll b, xanthophyll, carotenoids
The pigment which is bright or blue green in chromatogram is
Chlorophyll a
Colour of chlorophyll b in chromatogram is
Yellow green
Xanthophylls appear ____________ in chromatogram
Yellow
The colour range of carotenoids in chromatogram is
Yellow to yellow-orange
The substances that have an ability to absorb light, at specific wavelengths are called
Pigments
Maximum absorption of chlorophyll a occurs in ______and _______ regions
Blue, red
The chief pigment associated with photosynthesis is
Chlorophyll a
The three accessory pigments for light absorption in plants are
Chlorophyll b, xanthophylls and carotenoids
The function of accessory pigments is to absorb light and transfer the energy to __________
Chlorophyll a
Accessory pigments prevent __________________ of chlorophyll a
Photo-oxidation
Light absorption, water splitting, oxygen release, and the formation of high energy chemical intermediates are included in the process of _____________
Light reaction
High energy chemical intermediates formed during light reaction are
ATP and NADPH
The pigments are organised into two photochemical light harvesting complexes namely
PSI and PSII
In LHC, hundreds of pigments are bound to ________
Proteins
Each photosystem has all pigments except one molecule of _________ pigment.
Chlorophyll a
Each photosystem has all the pigments (except one molecule of chlorophyll a) forming a light harvesting system also called _______
antennae
Single chlorophyll a molecules forms
Reaction centre
n PSI, reaction centre chlorophyll a has an absorption peak at _______
700 nm
In PSII, reaction centre chlorophyll a has an absorption peak at _____
680 nm
PSI and PSII are also called _______ and ________ respectively
P700 and P680
In PSII, reaction centre chlorophyll a absorbs 680 nm wavelength of ______ light
Red
The excited electrons are picked up by an electron acceptor which passes them to _______________consisting of cytochromes.
Electron transport system
The movement of electrons in ETS is downhill in terms of which scale?
Redox potential scale
Electrons from ETS are passed on to pigments of which photosystem?
PSI
Electrons in reaction centre of PSI are excited when they receive red light of wavelength
700 nm
Electrons excited in PSI at 700 nm are transferred to another acceptor molecule that has higher __________
Redox potential
The whole scheme of transfer of electrons is referred to
Z scheme
Splitting of water is associated with which photosystem?
PS II
Electrons to replace those electrons removed from PSI are provided by
PSII
Electrons moved from PSII are replaced by electrons from ________
Splitting of water
PSII is located on
Inner side of thylakoid membrane
The process by which ATP is synthesised by cells is called
Phosphorylation
Phosphorylation occurs in which organelles?
Mitochondria and chloroplast
Synthesis of ATP from ADP and inorganic phosphate in the presence of light is called
Photophosphorylation
When the two photosystems work in a series, first PS II and then the PS I, then the process is called
Non-cyclic photophosphorylation
The products synthesised by non-cyclic photophosphorylation are
ATP and NADPH + H+
When only PSI is functional, phosphorylation occurs due to
Cyclic flow of electrons
Usually only PSI is functional in which part of chloroplast?
Stroma lamellae
Membrane of stroma lamellae lack PSII as well as enzyme -
NADP reductase
In stroma lamellae, excited electron instead of passing on to NADP+but is cycled back to
PSI complex
Cyclic flow results only in synthesis of ________
ATP
Cyclic photophosphorylation occursonly when light of wavelength beyond ______ nm are available for excitation.
680
In photosynthesis, ATP synthesis is linked to development of ___________ across a membrane
Proton gradient
ATP synthesis during photosynthesis occurs in the membrane of ______
Thylakoid
During photosynthesis, protons accumulate in the lumen of _________
Thylakoid
During photosynthesis, where does splitting of water molecules occur?
Inner side of thylakoid membrane
Protons produced by splitting of water molecule are accumulated in ____________
Lumen of thylakoids
During ATP synthesis, primary acceptor of electron transfers its electron to ___________
H carrier
NADP reductase enzyme is located on the ____________
Stroma side of membrane
Within chloroplast, protons in stroma decrease in number with decrease in pH of _________
Lumen
Breakdown of proton gradient is crucial for synthesis of ____
ATP
CF0of ATP synthase is embedded in _________
Thylakoid membrane
The part of ATP synthase that carries out facilitated diffusion of protons across membrane is
CF0
The portion of ATP synthase that protrudes on outer surface of thylakoid membrane on side towards stroma is
CF1
Conformational change in _____ particle of ATP synthase induces synthesis of ATP
CF1
Chemiosmosis requires a membrane, proton pump, ATP synthase and ___________
Proton gradient
Diffusion of protons across membrane creates enough energy to activate ___________
ATP synthase
Products of light reaction are -
ATP, NADPH and O2
ATP and NADPH are used to drive processes leading to synthesis of ___________
Sugars
Diffusion of O2out of chloroplast and use of ATP and NADPH to synthesise sugars are included in _______________ phase of photosynthesis
Biosynthetic
Biosynthetic phase of photosynthesis is dependent on
Products of light reaction
_____________ discovered that the first CO2fixation product was 3 carbon organic acid while working on algal photosynthesis
Melvin Calvin
The first stable product of Calvin cycle was identified as
3-phosphoglyceric acid
The 4 carbon product found as first stable product of CO2fixation in some plants was
Oxaloacetic acid
The plants in which first stable product during CO2fixation was PGA were called
C3plants
The pathway in which first stable product was found to be oxaloacetic acid was called
Hatch and Slack Pathway/ C4pathway
The primary acceptor of CO2is a _____ carbon compound in C3 cycle.
5
The primary acceptor of CO2that was a 5-carbon ketose sugar was found to be
Ribulose bisphosphate
The photosynthetic pathway that occur in all types of plants is
C3
The three main stages of Calvin cycle are
Carboxylation, reduction and regeneration
The fixation of CO2into a stable organic intermediate is called
Carboxylation
In C3 cycle during carboxylation, CO2is utilised for carboxylation of _________
RuBP
The enzyme catalysing the reaction of carboxylation in calvin cycle is
RuBP carboxylase
RuBP carboxylase catalyses the reaction of conversion of CO2to _______
PGA
Enzyme involved in carboxylation is called
RuBisCO
During reduction, series of reactions lead to the formation of ________
Glucose
During reduction in C3cycle, how many molecules of ATP are required?
2
2 ATPs during reduction in C3cycle are required for ________
Phosphorylation
Synthesis of one molecule of glucose requires ______ turns of C3cycle
Six
The number of CO2molecules fixed to form a molecule of glucose are
Six
During regeneration phase of C3cycle, the molecule that needs to get regenerated is
RuBP
Regeneration of RuBP requires how many ATPs for phosphorylation?
One
For every CO2molecule entering C3cycle, _____ and ______ molecules of ATP and NADPH are required, respectively
3 and 2
Six CO2molecule form one molecule of glucose in C3cycle is by utilising ____ ATPs.
18
A molecule of glucose is synthesised by utilising ____ NADPHs
12
CO2fixation in plants adapted to dry tropical regions occur by ___________
C4cycle
C4plants use _____ pathway as the main biosynthetic pathway
C3
Special leaf anatomy, tolerance to high temperatures, lack photorespiration are characteristic features of _______ plants
C4
C4plants which show response to high light intensities and have greater productivity biomass have their first CO2fixation product as ____
OAA
C4plants have special leaf anatomy called
Kranz anatomy
The large cells around vascular bundles of C4plants are called
Bundle sheath cells
Bundle sheath cells are characterized by having large number of
Chloroplasts
The cells in C4plants which are imperveous to gaseous exchange and have no intercellular space are called
Bundle sheath cells
Name two C4plants
Maize and sorghum
The primary acceptor of CO2in Hatch and Slack pathway is
Phosphoenolpyruvate
PEP in C4plants is present in
Mesophyll cells
Enzyme responsible for fixation of CO2in C4cycle is
PEPcase or PEP carboxylase
OAA is formed in
Mesophyll cells
The enzyme which is not present in mesophyll cells of C4plants is
RuBisCO
OAA before getting transported to bundle sheath cells gets converted into
Aspartic or malic acid
C4acids in C4plants are broken down in ________________ to release CO2and 3C compound
Bundle sheath cells
In C4 cycle, the 3-carbon molecule is transported back to the mesophyll where it
is converted to _______ again, thus, completing the cycle.
PEP
Photosynthetic pathway which is common to all plants is ______
C3
Bundle sheath cells of C4 plants are rich in enzyme -
RuBisCO
Bundle sheath cells lack enzyme ________ which is present in mesophyll cells
PEPcase or PEP carboxylase
Calvin pathway in C3plants occur in __________ while in C4plants, it takes place in _______
Mesophyll cells, bundle sheath cells
During carboxylation, RuBP combines with CO2to form 2 molecules of _____
3-PGA
The most abundant enzyme in the world is _______
RuBisCO
RuBisCO has active sites both for _________ and _______
CO2and O2
RuBisCO has greater affinity for _____ when CO2-O2ratio is equal
CO2
What determines binding of CO2/O2to RuBisCO?
Relative concentration of CO2/O2
O2binds to RuBisCO to produce?
Phosphoglycerate and phosphoglycolate
Photorespiration is limited to ____ plants
C3
When O2binds to RuBisCO instead of CO2, one molecule each of phosphoglycerate and phosphoglycolate are formed, this process is known as
Photorespiration
The process that neither synthesizes sugar nor ATP and releases CO2on expense of ATP is
Photorespiration
C4plants do not undergo photorespiration as they possess a mechanism that increases concentration of ____ at enzyme site
CO2
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 it is the factor which directly affects the process if its quantity is changed, is known as
Law of Limiting Factors
Law of Limiting factors was given by
Blackman
Incident light and CO2fixation rates at low intensity have _________ relationship
Linear
Light saturation in plants occur at ___% of the full sunlight
10
Increase in light beyond a point causes breakdown of ________
Chlorophyll
The concentration of CO2 is very low in the atmosphere (between ____ and ____per cent).
0.03 to 0.04%
CO2levels beyond _____% is damaging
0.05
C4plants show CO2saturation at
360 µl/L
C3plants show CO2saturationbeyond ___
450 µl/L
Temperature has more effect on _________ reactions
Dark
____ plants respond to higher temperature
C4
Optimum temperature of a plant depends on its ________
Habitat
Water stress causes the _______ to close hence reducing the CO2 availability.
stomata
Water stress leads to ________ of leaves
Wilting
