e'q Photosynthesis Flashcards
suggest why soda lime was not placed in the respirometer with the seedling grown in the light
- removing CO2 would prevent photosynthesis
- CO2 would be a limiting factor for photosynthesis
outline the structural differences the chromista cholorplast + the chloroplasts found in flowering plants
- chromista has fewer thylakoids
- chromista has no inter- granal lamellae
- plants have thylakoids in groups of more than three
- plants have strach grains
suggest why having a high conc of chlorophyll D is an advantage for Acaryochloris marina
- absorbs wider range of WL
- absorbs light at diff WL compared to aquatic plant species
- little light avaliable
what can you conclude about the composition of pigment A to D
- pigment A contains 2 molecules (2 spots above each other)
- pigment B and D contain 1 molecule (1 spot above line)
- pigment C contains 3 molecules ( 3 spots above)
- pigments A and C share molecules ( next to each other)
- all pigments are soluble
outline the importance of photosynthetic pigments in photosynthesis
- pigment absorb light
- electrons excited
- accessory pigments pass energy to primary pigments
- primary pigments loses electrons
- for light dependent reaction ( photophosphorylation)
suggest why chromista needs pigment that are different from those of other photosynthetic organisms
that they have to absorb light of short WL
that some WL doesnt reach them
state a material that can be used as the stationary phase in thin layer chromatography
silica gel
state the precise location of photosynthtic pigments in a choroplast
photosystem in the thylakoid membrane
on a chromotogram, how would you know what spot (pigment) is the most non polar
it would be the most soluble in moblie phase
why it is important to hold the TLC plate carefully by the edges + avoid damaging the surface of the plate
so that the movement of spots not affected by damage
why is it important to make sure the plate doesn’t touch the sides of the jar anywhere else
to avoid spots travelling in the wrong direction
suggest an advantage of working quickly as possible in step 1 (extraction of pigments) in TLC
to prevent contamination of the pigments
to reduce evaporation of solvent
state the name of the final electron accepter in the light dependent stage of PS
NADP
DCPIP is reduced in the Hill reaction. suggest + explain the function of DCPIP in the Hill reaction
- final electron acceptor
- replaces NADP - the usual electron acceptor
- allows photolysis to continue
explain why it was important that the pellet (sediment) was suspended in buffer solution + why it did not contain sucrose
buffer maintain the optimum pH
if theres no sucrose, no need to prevent damage to choloplast
suggest and explain 2 improvements that would increase the validity of the method ( the hill reaction)
use ice cold solution = prevents damage to components
use a water bath = so that temp of all tubes is controlled
explain why temperature has a greater effect on the rate of the light independent stage
light independent stage is controlled by enzymes
high temp will increase ESC’s formed
enzymes may be denatured at high temperatures
describe 2 ways in which the structure of granum is adapted to its function
large SA for increase in absorption of light
contain photosystems
contain electron carriers
w/ referece to the biochemistry of photosynthesis, explain why the theoretical rate of PS is not achieved at higher light intensities
at incr light intensity other factor becomes limiting
temp becomes limiting as calvin cycle invloves enzymes
CO2 conc becomes limiting as it is required for calvin cycle
which species would be bettter adapted to living in shady conditions
one that starts PS at low light intensity
one that reaches its max rate at lowlight intensity
one that has a greater ROPS
how would a structure of leaf adapted to shade differ from one thats living in sunlight
shade leaf will have more chloroplasts ; more thylakoids in choloplast, larger SA of leaves
describe how light is harvested in the choroplast membranes
primary accessory pigments are in the photsystems
light energy absorbed by pigment molecules
electron moves to higher energy level + returned to pigment
energy passed from one pigment to another
energy passed from to reaction centre
accessory pigments allow range of WL to be absorbed
suggest the role of DNA+ ribosomes in this organelle
DNA coding for enzymes
ribosome : proteins synthesis
proteins for pigments synthesis
protiens for electron carriers
enzyme for photolysis
enzymes for calvin cycle
- for all crops , inital increa in assimilation w/ increasing temp
- at higher temp the assimilation decreases
suggest a conclusion that could be drawn from the mean values
C3 plants assimilate decr Co2 than C4 plants
C4 crop 2
C3 crop 1
state possible uses of Tp within the plant
- amino acids
- carbohydrates
- hexose sugar
- lipids
from which molecule is TP synthesisied during the light independent stage
GP
A RuBP/ ribulose bisphosphate
B TP/ triose phosphate
C fatty acids
D amino acids
- accurate bc doesnt required light energy
- inaccurate bc needs ATP + reduced NADP, produced in light independent stage
name the enzyme responsible for fixing CO2 in the light independent stage
RuBISCO
Ribulose bisphosphate carboxylase
- increased photosynthetic activity during daylight
- as light intensity increases there is increased activity of the light dependent reaction
explain the shape of the curve for the rate of plant respiraton in fig
- day time temp generally higher than night time
- rate of respiration increases w/ increased temperature as its enzyme are temp dependent
what is happening at the points indicated by ltter L
Compensation point
- deactivation of RUBISCO will reduce CO2 fixation
- the light depdent reaction will reduce when the supply of NADP is reduced
- reduction in stomatal aperture will reduce CO2 available for fixation
suggest 2 ways in which the ultrastructure of the cholorplast can be altered by high temp
S: damage to chlorophyll
E: which will reduce the light dependent stage
S: damage to membranes in choloplast
E: which will reduce the light dependent stage
- at lower light levels, PS rate is greater when light is shown on the upper surface
- palisade cells are in the upper surface
- chloroplasts also present in cells at lower surface
- little diff bc leaf is thin
- no diff in rate at higher / light intensity
explain what is meant by a limiting factor
- the factor that will limit the rate
- when at lower level
anomlay is 28
repeat test
dessribe how the student could improve their experimental method+ the presentation of their data
improvements of presentation: units for light intensity should be shown , the table should be presentated to make comparisons of light intensity easier, th heading of the column threee could be improved ‘ rate of PS’ , present data as a graph
improvments to method: a more precise method measuring PS rate (eg O2 sensor) / gas syringe , control other vriables (same size pondweed), provide CO2 source ( so CO2 in excess, not limiting), smaller+ more consistent intervals between light + temp values should be used , repeats should be used
IV - temp
DV - conc of O2
CV - species of pondweed
identify one variable that was not controlled in the scientist method
pH
conc of CO2
age of pondweed
no. of leaves
D: incr temp incr O2 conc
D: PS is constant
E: O2 is a product of PS
E: temp acts as a limiting factor
E: no other factor was limiting
E: incr temp incr Ek of molecules
GP
- conc of GP decreases
- GP decr bc less CO2 available to react w/ RuBP to produce GP
RuBP
- conc of RuBP incr+ then decr
- RuBP incr bc it is not converted to GP
- RuBP incr as it is still being produced from TP
- RuBP decreases bc less GP avaliable to regenrate RuBP
DESCRIBE
-table 3.1 : light incr length + mass of both roots+ stems, group A has less growth than group b
- table 3.2: stem grows towrads the light w/ a few expectations, almost half the roots gro away from light , some appear unaffected by light or gorw towards light
EXPLANATIONS
- table 3.1 : more carbs produced during PS, light may trigger gorwth + germination
- table 3,2: auxins produced in shoot tip moves to side away from light , light allows PS, positive phototropism in stems , geotropism more important than photo tropism in roots ,-ve phototropism in roots, other reasons for varied datat eg conditions not natural
ii) unpaired t test
iii) comparing 2 means
- 8.1 is greater than 5.99 at 2 degrees of freedom
- therefore significant diff at p= 0.05
- not significant at p= 0.01
- indicates greater than 95% probability that difference is not due to chance
- null hypthesisi can be rejected at p=0.05
- D, antarctica habitat : lower max light levels , shorter day length / compeing planst
- optimum rate of PS in its habiatat is at a lower light intensity than that of Z mays
outline the wyas in which the heterotophic organisms are dependendt on plants
- heterotrophs obtain organic material from autotrophs (plants)
- plant produce organic molecules during PS
- plant produce O2 during PS
- glucose produced in PS are used in repsiration by heterotrophs
name the primary photosynthetic pigment in these photosystems
chlorophyll a
name an accessory pigment
chlorophyll b, xanthophyll, caroteniod
state the adv to the plant of having a range of accessory pigment in photosystems
able to absorb a range of WL
name the compound that is synthesisied in the light dependednt stage as a result of the geenration of an electrical +pH gradient across the thylakoid membrane
ATP
identify the enzyme that catalyses the fixation of CO2
RuBISCO
Identify the first stable product of CO2 fixation
GP / glycerate - 3 - phosphate
identify the compound that is regenrated in the calvin cycle so that more CO2 ca be fixed
RuBP
name 2 diff polysaccharides that can be sytnhesised from the end prodcuts off the LD stages of PS
starch
cellulose
rubisco
reduced NADP
TP
amino acid
RuBP
oxygen
explain what is meant by the terms autotrophs + heterotroph
autotrophs: can make organic molecules from inorganic molecules
heterotrophs : relies on organic molecules that have been made by another organism
granum
stroma
for membrane formation
fatty acid synthesis
- primary accessory pigments are in photosystems
- light energy absorbed by pigment molecules
- electron moves to higher energy level + returned to pigment
- energy passed from one pigment to another
- energy assed to reaction centre
- accessory pigment allow range of WL to be absorbed
suggest why the researchers concluded that the datat obtained from study E was not useful n evaluating the effectivenedd of the herbicide
no. of plots/samples was very small
- prevents non- cyclic photophosphorylation
- no electron available to form reduced NADP
- ATP production by cyclic photophosphoylation is not prevented
- less ATP + no reduced NADP available for light independent stage
energy given off from excited electron emitted by reaction centre
oxygen
- O2 only proudced on one stage of PS
- O2 produced might be used in respiration
CO2
- CO2 only used in one stage of PS
- CO2 produced during respiration might be used for PS
overall both could be an underestimate
- light intensity
- CO2 conc
- respiration
- at 0 , no PS
- between 0 and X: rate of respiration greater than rate of PS
- at x rate of respiration = rate of PS
- after X rate of PS greater than ROR
Name the prodcts of the L-D stage of PS
O2, ATP , reduced NADP
- prevents photophosphorylation
- cyclic, non cyclic
- no ATP for light independent stage
- no substrate made for respiration (glucose)
choloplast outer membrane
granum
stroma
intergranal lamellae
B, B, B, N, N, C
- radius of capillary tube
- cross sectional area of capillary tube
- use pi r squared
suggest how the student supplied the aquatic plant w/ a source of CO2
- sodium hydrogencarbonate
- bubble in CO2
- dry ice
- would dissolve in water
- used in respiration
- may escape the colection apparatus
- trapped in air spaces in the leaf
- nitrogen was present in air spaces in the leaf
- nitogen leaves the plants w/ the O2
- Nitrogen comes out of solution
- higher than in atmosphere
- plant is respiring as produces CO2 during respiration
- CO2 is present in excess
- CO2 comes out of solution
- less as some CO2 will dissolve in solution
- les as CO2 used in PS
intensity
- in deeper water there is lower light intensity
- these pigments can absorb what little light there is
WL
- not all WL of light can penetrate
- theses pigments can absorb WL of light that can penetrate deeper water
name the products of the L- D stage that are used in the calvin cycle
- ATP
- reduced NADP
Dis cuss the fate of TP in the calvin cycle
- regenerates RuBP
- so cycle can continue for further CO2 fixation
- formation of glucose/starch
- formation of lipid /amino acids, proteins
- most TP used to produce RuBP + rest for production
- O2 used + CO2 produced
- involves calvin cycle
using both figues , describe=explain the likely effect on PS of an incr in the O2 conc
- decr rate of PS
- less RuBISCO available for CO2
- less CO2 for calvin cycle
- less GP produced
- less RuBP generated
- O2 cannot bind to PEP carboxylase
- PEP carboxylase cannot ‘fix’ O2
- PEP carboxylase only specific to CO2
- used as a control to compare w/ other filter
- same vol of indicator so colour change are comparable
- carry out constant temp as temp affects enzyme activity
- carry out repeats to calc mean
- carry out in darkened room so only light of desired WL enters
- tube same distance from light source so light intensity is the same
name the pigment at the reaction centre of photosystmes 1 + 11
chlororphyll a
explain the change observed in the tube exposed to green light
- leaf reflects green light
- green light cannot be used in PS
- no photolysisi/spliiting of water
- no CO2 foxed in light independent reaction
- some CO2 produced during respiration
- slight incr in CO2 , incr acidity
- PS involves enzymes
- temp can be reduced by ventilation
- incr CO2 in enviro by burning fuel
- higher CO2 so no longher limiting factor
- easier to control water supply
- easer to control use of pesticide
