3.5.1 Photosynthesis Flashcards
3.5.1 Photosynthesis
what are the two main stages of photosynthesis
light dependant reaction
light independant reaction / kelvin bensin cycle
what is the gcse general equation for photosynthesis
6CO2 + 6H2) —-(light)—> C6H12O6 + 6O2
draw out a chloroplast with labbels
check with photosynthesis pack
https://stock.adobe.com/images/chloroplast-structure-with-titles/185026077
should include :
outer membrane
intermembrane space
inner membrane
stroma (aqueous fluid)
granum (stack of thylakoids)
thylakoids
lamella
lumen (inside of thylakoid)
what do thylakoids do, and when are they used LDR or LIR
Thylakoids contain chlorophyll and other pigments that can
absorb light at a variety of wavelengths (light dependent reactions)
what are starch grains used for
Starch grains store excess carbohydrates made in photosynthesis.
you test starch with an iodine solution
what are ribosomes used for in a chloroplast
Ribosomes for protein synthesis
why is granum useful for
Granum is a stack of thylakoids. Stacking thylakoids maximises surface area for light capture
what is the purpose of stroma , and when is it used LIDR or LDR
Stroma contains enzymes for light-independent reactions
which stage uses water and produces oxygen
kight dependant reaction
which stage reduces carbon dioxide to produce glucose
light INdependant reaction
what two key products are produced in light dependant reaction
ATP
and
NADPH
what two key products are produced in light independant reaction
suger
water
also:
NADP+
ADP
where does the does the light dependent reaction take place
in the lumen of the thylakoid
what two pigments does a plant have and what type of wave length of light do they reflect
chlorophylls (primary pigments)
carotenoids (accessory pigments).
Chlorophyll is the pigment that gives plants their green colour by reflecting green light. Carotenoids reflect red, orange or yellow light.
where does the light indipendent reaction take place
in the stroma of the chloroplast
somtimes the light independant reaction is described as the dark phase . why is that incorrect ?
as it does not onlytake place during the dark , it can take place during any part of the day . even though the process uses no llight.
what is an antenna complex/photosystem
chlorophylls and carotenoids are grouped in clusters called antenna complex or photosystems located on the thylakoid membrane carotenoids absorb photons of light which then transfer energy to chlorophyll A which are located at reaction centres (near the bottom )
describe the structure of a chlorophyll A molecule
A Polar head with a magnesium atom in the centre. This absorbs the light.
A Non polar tail which anchors the chlorophyll molecule into the thylakoid membrane.
Chlorophyll B very similar, but less abundant
what are the primary pigments and what type of colour wavelength do they absorbe
hlorophylls - primary pigments:
Chlorophyll a & chlorophyll b absorb light mainly in the red and blue violet regions of the electromagnetic spectrum
what are the accessory pigments and what type of colour wavelength do they absorb
Carotenoids – accessory pigments:
carotenes and xanthophylls absorb light from the blue violet region of the spectrum. Absorbing wavelengths of light not absorbed by the chlorophyll and then passing the energy to chlorophyll A molecules.
describe the diffrence between the two photosystems
Photosystem I : arranged around a chlorophyll a molecule with an absorption peak of 700nm - called P700
Photosystem II : arranged around a chlorophyll a molecule with an absorption peak of 680nm - called P680
what is the equation for the Rf value
Rf value = distance travelled by pigment / distance traveled by the solvent
how does photosynthesis maximise its effeciency
by making sure to use multiple diffrent pigments inoder to get a range of wavelengths that are absorbed
what is the importance of the accessesory pigment
inorder to cover a broader range of wavelengths
where might you find plants with high level of accesssory pigemtns
with areas of low level of light
what is the diffrence between a Absorbtion spectra and a Action spectra
Absorbtion spectra :
shows the absorbstion of light at diffrent wavelengths for each pigment over a range of wave lengths
maybe have multiple lines representing diffrent pigments
action spectra :
shows the rate of photosynthesis at diffrent wavelengths of light
what does it mean to get reduced
gain electrons
oxi number to decrease
loss of oxygen
gain of hydrogen
what does it mean to get oxidised
loss if electrons
oxinumber increases
gain of oxygen
loss of hydrogen
what are co-enzymes
Co- enzymes are molecules that aids an enzyme . they transfer a chemical group (like hydrogen) from one molecule to another
what are the two products of the light dependent stage , and what are their roles
1) ATP
Light energy is transformed into chemical energy. Electrons are used to make ATP in photophosphorylation. This is then used to drive other biochemical reactions in the light independent stage
2) Reduced NADP
Protons are used to reduce NADP (which acts as a hydrogen carrier). The reduced NADP is used in the light independent reactions
what is the role of reduced NADP
it is a hydrogen carrier
NADP transfers hydrogen from LDR to the Calvin cycle. As it accepts the hydrogen to be reduced, the concentration of protons in the stroma becomes lower.
Reduced NADP can be represented by NADPH2 or NADPH + H+ or simply reduced NADP
what are the two ways tha ATP can be synthesized ?
1) non-cyclic photophorolation - Involves photosystem 1 and 2 and includes reducing NADP to reduced NADP
2) cyclic Photophosphorilation - photosystem 1 only and no reduced NADP is made.
How do the accessory pigments absorb photons
Accessory pigments absorb photons of light, then pass the photons of light down to the Chlorophyll a molecules which are situated in the Reaction Centre at the bottom.
blurb about the light dependant reaction ,
how does it happen also draw a diagram of the light dependant reaction
https://www.pinterest.co.uk/pin/565061084499264827/
- Light energy (photons) strikes chlorophyll a in PSII exciting its electrons, boosting 2 of them to a higher energy level. These electrons leave the chlorophyll molecule. The chlorophyll molecule has now been ionised. It has been oxidised. This process is know as photoionisation.
- The electrons in the high energy state are accepted by a molecule called an electron carrier in the thylakoid membrane. The electron carrier has been reduced.
- The electrons lost from chlorophyll in PSII need to be replaced. Light energy splits water into protons, electrons and oxygen (photolysis). The electrons are accepted by the chlorophyll a molecule. This occurs in the thylakoid space (lumen)
- Electrons are passed along a series of electron carriers in a series of redox reactions. This electron chain is in the thylakoid membrane. As electrons pass from carrier to carrier electron energy is lost and used to pump protons from the stroma into the thylakoid space to produce ATP by the chemiosmostic theory (explained later)
- Electrons enter PS I where light excites them, boosting them to an even higher energy level.
- Electrons enter a final electron carrier
- Electrons and protons reduce NADP to NADPH2 which pass to the Calvin cycle with the two ATP made.
in what direction are hydrogens pumped in during the light dependant reaction
the hydrogen ions move from the stroma into the thylakoid lumen
what is it called when chloroplast are ioned by light
photoionisation.
what is it called when water is split into 1/2 O2 and 2H+ by light during the photosystem 2
photolysis
why is cyclic phosphorylation used
If there is no NADP available then the electrons fall back into the electron transport chain (about half way along) and generate 1 ATP. Electrons can be recycled through PSI until NADP is available.
this is a question on cyclic phosporilation :
1) which photosystem is involved ?
2) is reduced NADP produced in the cyclic reaction ?
3) is ATP produced in the cyclic reaction ?
4) is oxygen gas produced in the cyclic reaction
5) why is the reaction described as cyclic
1) photosystem 1
2) no
3) yes
4) no
5) because the same electron is used to produced as much atp as the plant requires , best shown from the z-diagram of cyclic phosphorylation
what is the definition of chemiosmosis
Chemiosmosis is the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient. An important example is the formation of adenosine triphosphate by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis.
describe the stages of chemiosmosis
1) As electrons flow along the electron carriers in the thylakoid membrane, they provide energy to pump protons from the stroma into the thylakoid space (lumen).
2) This creates a high concentration of protons in the thylakoid space and low in the stroma
3) The thylakoid membrane can maintain the electrochemical gradient as it is impermeable to protons.
4) The protons will eventually flow back into the stroma through ATP synthase channels proteins.
5) The protein channels form small granules on the membrane surface so are known as stalked granules.
6) The flow of protons cause changes in the structure of the enzyme that catalyse the formation of ATP from ADP and inorganic phosphate.
what type of phosphorylation occurs in the light dependent reaction
oxidative phosphorilation (normally through a channel / carrier protein)
why can the thylakoid membrane maintain the electrochemical gradient
as it is impermeable to protons.
draw out the calvin benson cycle
and also blurb about the steps
https://quizlet.com/gb/853087326/lir-diagram/
- Carbon dioxide diffuses into leaf via stomata, dissolving in the water surrounding palisade mesophyll cells.
- Carbon dioxide combines with the 5 carbon compound ribulose bisphosphate (RuBP) using the enzyme RUBISCO to form an unstable 6C compound.
- Unstable 6C compound immediately breaks down into 2 molecules of glycerate 3-phosphate (GP).
- Using one ATP molecule from the light reaction, GP is phosphorylated and then reduced to triose phosphate using the hydrogen from reduced NADP.
- Triose phosphate molecules combine in pairs to form hexose sugars.
- The majority of the triose phosphate molecules produced are used to regenerate RuBP using ATP from the light dependent reaction to supply energy and phosphate. This allows the cycle to continue.
1) where does the light independent stage take place
does it need light
2) how what inorganic compound does it use to make hexose suger
1) Occurs in the stroma of the chloroplast
Does not need light
2) CO2
what are the three rules for something to be classified as an organic compound
has to have carbon
has to have a carbon-hydrogen bond
has to have a carbon-carbon bond
what are the three main stages of the calvin bensin cycle and define them
- Carbon dioxide fixation: CO2 is fixed by the reaction of RuBP with CO2 to produce glycerate 3-phosphate using the enzyme RuBisCO.
- Phosphorylation of glycerate 3 phosphate using ATP. Reduction of GP to triose phosphate (using reduced NADP which then becomes oxidised).
- Regeneration: 2 Triose Phosphate are needed to regenerate RuBP (ATP required),1C would be left, so 6 turns of Calvin cycle and 6 CO2 are needed to synthesise 1 glucose molecule.
what does GP stand for and how many carbon atoms does it have
Glycerate - 3 - phosphate
3 carbons
what does TP stand for and how many carbon atoms does it have
triose phosphate
3 carbons
what is regenirated during the calvin bensin cycle
RuBP (ribulose biphosphate )
it has 5 carbons
what is the enzyme used in kalvin bensin cycle
rubisco
could also think of the bit at the end -co as like co enzyme
what does the calvin bensin cycle produce
hexose suger
lipids
amino acids
how much reduced NADP and ATP is used
and between where / when
and what for
3 ATP are used all together
2 ATP are used and add a phosphate group to the GP to make it TP ATP —> ADP
1 is used to regenerate RUBP losing its phosphate group
ATP —> ADP
2 NADP is used all toghether
is is used to reduce GP into TP NADPH —> NADP
how does light effect TP
Decreasing light intensity means less ATP and reduced NADP, so less TP is made since ATP and reduced NADP are needed to make TP from GP.
how does light effect GP
Decreasing light intensity means produces less ATP and reduced NADP , this causes a build up of GP as there is a lack of ATP and reduced NADP to go to TP
how does light effect GP
Decreasing light intensity means less ATP and reduced NADP, so less RuBP because RuBP is still being used up to make GP but RuBP is not being regenerated as GP cannot be made into TP, which is needed to make RuBP.
how does carbon dioxide concentration effect TP
As carbon dioxide increases more RUBP can bind to CO2 which produces more GP and therefore more TP
how does carbon dioxide concentration effect GP
As carbon dioxide increases GP increases. Because more CO2 is fixed, so more GP is made.
how does carbon dioxide concentration effect RUBP
As carbon dioxide increases means there is more reactions between RUBP and CO2 , no more RUBP can be made but it is more frequently used
how does temperature effect TP
As temperature increases transpiration increases and therefore less ATP and reduced NADP is made thererfor less GP is made and therefore less TP
however there is more energy for enzymes
how does temperature effect GP
As temperature increases GP Increases. But at high temperatures will decrease because the enzyme RuBisCO denatures and less carbon dioxide fixed, so less GP will be made and so less TP is made.
how does temperature effect RUBP
As temperature increases transpiration increases and therefor less ATP and reduced NADP . the lack of ATP and reduced NADP slows down the calvin bensin cycle therefore less RUBP is being used
but also more energy for enzymes
how is nitrogen taken up by a plant and how is it used in a plant
Plants take up nitrates from the soil, the nitrogen is then used in the synthesis of amino acids, then proteins by condensation.
how are lipids made in plants and what are there uses in a plant
Lipids are made of Carbon, hydrogen and oxygen only, the same three elements as carbohydrates but in different proportions. The plant can form its own lipids for waxy cuticles etc.
how is glucose made and what is it used for in a plant
Glucose formed from TP can be condensed to form starch and the isomer Beta glucose will form cellulose, fructose (another hexose) and sucrose (a disaccharide) can be formed.
how is nitrates transported in a plant
xylem
how are amino acids transported in a plant
phloem
what is the appearance of a plant with nitrogen deficiency
reduced growth of all organs and chlorosis
what is chlorosis
Chlorosis = yellowing of leaves, as a result of loss of chlorophyll.
info card read and recite
In the case of magnesium deficiency the symptoms generally start with mottled chlorotic areas developing in the interveinal tissue. The interveinal laminae tissue tends to expand proportionately more than the other leaf tissues, producing a raised puckered surface, with the top of the puckers progressively going from chlorotic to necrotic tissue
1) what is the role of magnesium in plants
2) where is it transported
3) what are the signs of deficiency
1) Forms part of the Chlorophyll molecule
Found within the hydrophylic head (the hydrophobic tail is a long hydrocarbon molecule that anchors the chlorophyll within the thylakoid membrane)
The head is used for absorbing and transducing the light energy into chemical energy.
Used for activation of ATPase
2) zxylem
3) chlorosis , stunt in growth
The chlorosis shows up in older leaves first, because plant moves Mg+ to newer leaves.
what is the law of limiting factors
When a process depends on two or more factors, the rate of that process is limited by the factor which is in shortest supply
what are the limiting factors of rate of photosynthesis in a plant
Light intensity
Availability of water
Availability of carbon dioxide
Availability of chlorophyll
Temperature
how does tempreatur effect photosynthesis rate
The light-independent reaction of photosynthesis is controlled by enzymes. Temperature affects enzyme reactions.
As temperature increases, collision frequency between reactant particles and between reactant and enzyme increases. This increases the rate of reaction up to the optimum temperature.
Beyond the optimum temperature however, enzymes begin to be denatured. Their tertiary structure breaks down, changing the shape of the active site so that reactant molecules no longer fit.
how does atmospheric carbon dioxide effect photosynthesis rate
Carbon dioxide is essential for the photosynthesis process. It is used during the light-independent stage to carboxylate ribulose bisphosphate.
The normal concentration for atmospheric carbon dioxide varies between 0.03 % and 0.04 %.
Plants are adapted to survive in varying concentrations of CO2, but the higher the value, the higher the rate of photosynthesis.
Plants may therefore be able to remove some of the CO2 released by human activity from the air.
what is the compensation point
wherer the rate of photosynthesis matches the rate of respiration
what is it called when :
A series of small reactions controlled by enzymes (like photosynthesis)
Metabolic pathway
what is :
Phosphorylation
adding phosphate to a molecule (ADP – ATP)
what is :
Photophosphorylation
adding a phosphate group using light
what is :
Photolysis
Splitting (lysis) of a molecule using light (photo)
what is :
Hydrolysis
Splitting (lysis) of a molecule using water (hydro)
what is :
Decarboxylation
The removal of carbon dioxide from a molecule
what is :
Dehydrogenation
The removal of hydrogen from a molecule
what is :
Redox rections
Reactions that involve oxidation and reduction (more on this on the next page)
how is light level used in agriculture
by light levels of spesific wavelength being released from lamps . it increases the production of ATP and reduced NADP in LDR . as more light hits the chlorophyll this causes more excitation
how is CO2 used in agriculture
green houses controll concentrations of CO2 . this is used to link RUBP which makes GP and therefore TP which is later used for amino acids lipids and sugers. in Light independant reaction
put green houses near a factory then CO2 wont be a limiting factor
how is temperature used in agriculture
green house (closed enviroment) in which we can controll tempreature .
this increases kenetic energy and therefor the likly probablilty for an enzyme to react is greater , while also frequency increasing
