photosynthesis Flashcards
What all are required for photosynthesis
chlorophyll, CO2, light
Who discovered oxygen
john priestely
Candle burning and mouse suffocating experiments by
JOH PRIESTSLY
who discovered sunlight is essential for photosynthesis
jan igenhousez
who proved only green parts of plant release oxygen
jan ingenhousez
who provided evidence for production of glucose
julius von sachs
which algae did TW engelmann use
green algae- cladophora
TW engelmann bacteria accumulate mainly in ___ and ___ light of splits spectrum
red and blue
action spectrum of ___ similar to absorption spectrum of ___ and ___
photosynthesis, ch-a and ch-b
what did corneus von niel prove
photosynthesis is essentially a light driven compound that uses hydrogen from a suitable oxidisable compound to reduce carbon to carbohydrates
the oxygen released in photosynthesis is released from
water
how was it proved oxygen is released from water photosynthesis process
radio isotope technique
____ cells of green leaves have large number of chloroplasts
mesophyll cells
chloroplast align themselves along the ____ of the mesophyll cells because
walls, optimum quantity of incident light
constituents of chloroplast are
grana, stroma lamellae, matrix stroma
what does membrane system of chloroplast do-
is it light or dark reaction?
it absorbs and traps light, and synthesizes atp and nadph
its a light reaction
what does stoma of chloroplast do-
is it a lighter dark reaction?
synthesizes sugar, which is turned to starch
dark rxn
light reactions are also known as-
they are dependent on ___
photochemical rxn
directly dependent on light
how can we separate pigment of plants
paper chromatography
what are pigment
substances that can absorb light at specific wavelengths
dark reactions are also known as-
they are dependent on-
carbon reactions
dependent on products of light reactions
are dark reactions light independent
no
4 pigments of plants
ch-a, ch-b, carotenoids, xanthophylls
___ is chief pigment associated with photosynthesis is
ch-a
role of accessory pigments
absorb light at other wavlenghts- so enable wider range of wavelenght incoming to be utilised for photosynthesis, and prevent ch-a from photo-oxidation
what are accessory pigments
other thylakoid pigments like ch-b, carotenoids, xanthophylls
what happens in light reactions
light is absorbed, water is split, oxygen is release, high energy intermediates are formed (ATP, NADP)
types of light harvesting complexes and their peaks
PS1- 700, PS2- 680
what are light harvesting complexes and what are they also knows as
LHC are made up of hundreds of pigments bound to proteins.
they are also knows as photosystems
PSA1 AND PPSA2 are named in the order of their-
discovery
What are the two types of reactions that occur within chloroplasts during photosynthesis?
The two types of reactions are light reactions (photochemical reactions) and dark reactions (carbon reactions).
electron transport system consists of
cytochromes
movement of electrons in z-scheme in ETC is-
downhill
are electrons used up in the electron transport chain?
no
electrons in z-scheme are passed onto another acceptor molecule of _____ reduction potential
higher
in photosystem 2 ___ is released
ADP+ iP= ATP
in photo system 1 what is released
NADP = NADPH + H
what is z-scheme
starting from ps2- uphill to acceptor- downhill to PS1 through ETC- excites electrons- transfer to another acceptor- downhill to NADP which is reduced to NADPH AND H+
the splitting of water is associated with whic LHC
PS2
electrons of PS2 are replaced by-
electrons of PS1 are replaced by-
1) splitting of water
2) PS2
where is PS2 physically located
on the inner side of thylakoid membrane
ATP carries ___ energy in its chemical bonds
bond energy
what is photophosphorylation
the process of synthesis of ATP from ADP and inorganif phosphate in the presence of light.
when two photosystems work-
when only one photo system works- (whichone?)
1) non cyclic photophosphorylation
2) cyclic photophosphorylation- PS1
where does non cyclic photophosphorylation occur
granal thylakoid
where does cyclic photophosphorylation
stroma lamellae
products of non cyclic photophosphorylation-
products of cyclic photophosphorylation-
1- ATP and NADPH
2- ATP
cyclic photophosphorylation only occurs when
wavelenght of light greater than 680 is present since PS1 is involved
chemiosmosis requires
a membrane, a proton pump, a proton gradient and atp synthetase
ATP synthetase enzyme consists of 2 parts (and functions)
1)CFo- embedded in the thylakoid membrans anf forms a transmembrane channel for the facillitated diffusion of proton across membrane.
2) CF1- it protrudes on the other side of the thylakoid membrane on the side that faces the stroma
in chemiosmosis theory, the protons produced by ____ accumulate in the ____ of the _____
splitting of water- lumen- thylakoids
in chemiosmosis theory the NADP reductase enzyme is located on the ____ side of the membrane.
stroma
in chemiosmosis theory- the protons in the stroma ____ and in the lumen____
decrease-increase
in chemiosmosis theory why is the proton gradient broken down and how is it done.
the breakdown of the gradient provides sufficient energy to cause a conformational change in the CF1 particle of the ATP synthetase which makes the enzyme synthesize several molecules of energy packed ATP.
it is done due to the movement of protons across the membrane to the stroma to the transmembrane channel of the CFo of the ATP synthetase
in chemiosmosis theory energy is used to pump ______ across a membrane to-
-protons
-create a gradient or high conc of protons in the thylakoid lumen.
how are protons collected in the thylakoid lumen?
1) splitting of water by PS2
2) by the H+ carrier phylloquinone that removes a proton from stroma while transporting an electron. when electron is passed on it release the H+ in the lumen.
3) by FNR , after it produces NADPH, it releases H+ into the lumen.
FNRM full form
ferredoxin NADP+ reductase
how is ATP formed in chemiosmotic hypothesis?
when the proton gradient is broken down and protons travel across the membrane, from the lumen to the stroma, through the transmembrane channel CFo of the ATP synthase enzyme, energy is released, which facilitates in the formation of ATP from ADP and iP
what are the total products of light reactions and what happens with them?
products of light reactions are- O2, ATP, NADPH
-O2 diffuses out
-ATP and NADPH are used to make food i.e. sugars.w
what is the biosynthetic phase of photosynthesis?
-ATP and NADPH are used to make sugars.
is biosynthetic process light or dark rxn
dark rxn
what did melvin calvin discover?
using 14C and radio isotope techniques, he discovered that the first CO2 fixation product was a 3 carbon phospho glyceric acid (PGA).
he also contributed in mapping out the entire biosynthetic pathway hence the cycle was also named Celvin cycle.
what was the name of the first stable product of CO2 fixation with 4 carbon atoms
oxaloacetic acid
how are plants differentiated on the basis of their first stable CO2 fixation products
if first stable product=
-C3 acid (PGA) then c3 pathway/calvin cycle
-c4 acid(OAA) then c4 pathway.
what was the acceptor molecule in C3 sycle?
5 carbon ketose sugar- ribulose bisphosphate (RuBP)
how many steps are there in C3 cycle
1)carboxylation
2)reductions
3)regeneration
Is C3 cycle cyclic or non cyclic
cyclic
what happens in carboxylation in C3 cycle
the carbon dioxide is utilized for the carboxylation of the RuBP with the help of RUBISCO enzyme which results in formation of 2 PG
how many C3 cycle required for production of one molecule of glucose
6 turns
what happens in reduction step of C3 cycle
series of reactions that lead to the formation of glucose.
2 ATP and 2 NAPD are used to reduce 3-PGA to triphosphate per CO2 molecule fixed.
what happens in regeneration step of C3 cycle
one ATP s used from phosphorylation to regenerate RuBP.
why is regeneration a crucial step in the C3 cycle
because regeneration of the RuBP is necessary if the cycle is to continue uninterrupted.
how many ATP and NADPH and CO2are used to make 1 molecule of glucose.
how is the difference between the needs of ATP and NADPH met in C3 cycle?
-CO2-6
-ATP-18
-NADPH-12
the difference is met by the extra formation of ATP through the cyclic phosphorylation.
how many ATP and NADPH in one C3 cycle
3 ATP
2 NADPH
special feature of C4 plants
-kranz anatomy in leaf
-tolerance to high temperatures
-respond to high light intensities
- do not have process photo respiration
-greater productivity of biomass
how are bundle sheath cells characterized
may form several layers around vascular bundles. they are:
-thich walled and impervious to gas exchange
-large number of chloroplast
-no intercellular spaces
give examples of C4 plants
maize and sorghum
what will help identify c4 plants
presence of bundle sheath cells inleaf anatomy
In c4 plants-
mesophyll cells lack ____ and have ____
bundle sheath cells lack ____ and have____
- rubisco, pepcase
-pepcase, rubisco
what are other intermediate compounds formed in C4 cycle and where are they formed?
malic acid, aspartic acid, formed inmesophyll cells
where does decarboxylation take place in C4 cycle and how is the CO2 release utiliZED.
IN BUNDLE SHEATH CELLS
-TH CO2 released is used in C3 cycle which takes place in bundle sheath cells
regeneration of PEP takes place where in C4 cycle?
mesophyll cells.
calvin pathway occurs where in C3 and C4 plants?
C3= mesophyll cells
C4= bundle sheath cells
