Photosynthesis Flashcards
What does the chloroplast contain
Starch
Granny
Ribosome
Inter graham lamella
Stroma
DNA
Thylakoids function
Have large SA for light energy to be absorbed
Stroma
Is a fluid containing free moving enzyme and substrates for Calvin cycle - LIR
Process of LDR step 1
Light energy excites electron in the chlorophyll
Absorbed by the PSII
It moves to a higher energy level
These high energy electron moves along the electron chain transport (ETC) to PS1
LDR step 2
Excited electron from chlorophyll leave the PS 11 to move along the electron transport chain they must be replaced
The light energy splits water into protons electrons and oxygen
PHOTOLYSIS
H20 —> 1/2 O2 + 2e+ 2H+
LDR step 3
The excited electrons lose energy as they move along the ETC
The energy is used to transport the protons into the thylakoids so that the thylakoids has higher conc of protons than the stroma.
—> this forms a electrochemical gradient across the membrane
Protons move down their concentration gradient into the stroma, via the enzyme ATPsynthase and inorganic phosphate (Pi)to form ATP
CHEMIOSMOSIS
LDR step 4
Light energy is absorbed by PS 1 which excites the electron again to an even higher energy level
Finally the electrons are transferred to NADP along with proton from the stroma to form NADPH
Cyclic phosphorylation
Only PS1 involved
Water is not involved
Oxygen is not involved
NADPH Is not synthesised
Used to produce ATP additional in order to meet the cell energy demand
(Only produce small amounts)
Electrons returned to chlorophyll molecule after aiding the reproduction (ATP
Non cyclic phosphorylation
PS1 and PS2 are involved
Photolysis of water is required
Oxygen is evolved
NADPH is synthesised
Products can be used for the LIR
Electrons has been given to PS1 therefore needs an electron to come from breakdown of water
What products from LDR to LIR
ATP
NADPH
Calvin cycle mnemonic
Rubi
Comes
From
PG
To GET
Glucose
Calvin cycle step 1
CO2 enters the stomata and diffuses into the stroma of the chloroplast
Combined with RuBP andd is catalysedd by RUBISCO
This gives an unstable 6 carbon compound, which quickly breaks down into 2 molecules of glycerine 3 phosphate (GP)
Calvin cycle step 2
The hydrolysis of ATP (from LDR) provide energy to turn 3-GP to GALP
This requires H+ ions which come from (NADPH -LDR) . NADPH to NADP
Some GALP is then converted into glucose
And come continue to regenerate RuBP
Calvin cycle step 3
Two GALP molecule used to make glucose
5/6 GALP molecule produced are used to regenerate RuBP
Regenerating RuBP uses the rest of ATP
Produced by LDR
How does light intensity affect photosynthesis
- affect the amount of reduc3 NADP and ATP produc3d in the LDR
-both light intensity and wavelength affect the rate of photosynthesis
Limiting factors affecting photosynthesis
In greenhouse, extra CO2 can be supplied to increase the rate of photosynthesis (their yield)
-CO2 for the Calvin cycle
Limiting factor affecting Temperature
Each step is controlled but enzyme
Optimum temperature should be applied
-kinetic energy
-more collision
-faster rate of reaction
What is action spectrum
Shows the rate of photosynthesis for all wavelength of light as a % of the maximum Possible rate
What colour does the maximum photosynthesis rates occur
1) blue light
2) red light
What minimum photosynthesis rates occur in
Green yellow light
What colour is chlorophyll a
Blue green (found in all photosynthesis. Plant + highest quantity)
What colour is chlorophyll b
Yellow - green
What colour is carotenoids
Orange carotene/ yellow xanthophyll
What colour is phaeophytin
Grey
What does photosynthetic pigments have
Different absorption spectrum
-having different proportions of photosynthesis pigment = different colour of leaves
What does each pigment have
Each pigment can absorb a different range of wavelength of light within the visible light spectrum
What wavelength and colour doesn’t absorb well and why
500-550 nm is poorly absorbed by all pigments , so this wavelength is reflected which is why leaves look green
Why is it an advantage why plants have multiple pigments
A wider range of wavelength is absorbed
Therefore more light energy is absorbed for the LDR (more photoionisation of chlorophyll)
Absorption spectrum
A graph showing the amount of light absorbed by a pigment in the different wavelength of light
Where does the light dependant reaction occur
Thylakoids membrane
Where does the light independent reaction occurs
Stroma
What is carbohydrates used for
The glucose is used for respiration
Whats is lipids used for
