Photosynthesis. Flashcards
How is the leaf adapted to absorb light?
Translucent cuticle
High surface area to volume ratio
Dense chloroplasts.
How is the leaf adapted to diffuse gases?
Air spaces
Guard cells
Stomata.
How is the leaf updated to transport water and glucose?
H2O- xylem
Glucose- phloem.
Where is each element of photosynthesis made/is?
CO2- LIS
H2O- LDS
Glucose- LIS
Oxygen- LDS.
Where does each stage of photosynthesis occur?
LDS- thylakoid membrane
LIS- stroma.
Pigments definition.
A chemical that absorbs specific wavelengths of light
Can be separated by chromatography.
Absorption spectrum.
Show the amount of light absorbed at each wavelength by each pigment
Multiple pigments= light at more wavelengths are absorbed.
Action spectrum.
The rate of photosynthesis at each wavelength.
Non-cyclic photo phosphorylation.
Oxygen made as a by product
Reduced NADP made in LIS
ATP in LIS.
Non-cyclic phosphorylation process.
1) Light energy is harvested and passed to chlorophyll a
2) 2 excited e- leave chlorophyll a and enter ETC. They lose energy as they move through and the H+ pumps gain energy
3) Photolysis of H2O replaces e- at PSII. Requires light energy and an enzyme
4) The H+ pumps pump H+ from the stroma into the thylakoid lumen, form a H+ gradient and a lower pH
5) H+ move by FD through ATP synthetase
6) Movement of H+ through ATP Synthetase, provides energy for photo-phosphorylation
7) Light is harvested and 2e- in chlorophyll a of PSI are excited. These enter the stroma
8) NADP gains e- and H+ and becomes reduced. NADP is the final e- acceptor.
The Z scheme.
Study diagram.
Cyclic photo phosphorylation purpose and process.
To produce ATP
1) Photo excitation, 2e- excited in chlorophyll a
2) Excited e- pass through the ETC and return to PSI. E- lose energy, H+ pump gains energy
3) Protons pumped from stroma and thylakoid lumen, creating electrochemical gradient
4) Chemiosmosis, H+ go through ATP Synthetase, down concentration gradient
5) Photophosphorylation.
Process of cyclic and non-cyclic.
Study diagram.
Photosystems present in Ps.
Non cyclic= PSII and PSI
Cyclic= PSI.
When does photolysis occur and why?
In Non cyclic because e- need to be replaces at PSII.
Products of cyclic and non cyclic.
Non= ATP and reduced NADP
Cyclic= ATP
Go to LIS.
Which stages require light.
Non cyclic= photoexcitation, photophosphorylation, photolysis
Cyclic= Photoexcitation, photophophorylation.
LIS/ Calvin cycle process.
1) 5C RuBP is carboxylated(from CO2) by Rubisco to form unstable 6C intermediate
2) Splits into 2 3C GP molecules
3) GP is reduced by reduced NADP oxidising(releases H+) and ATP releasing energy forming 2 3C TP molecules
4) 1C from TP used to make glucose(from 6 cycles)
5) The other 5C form RuBP using ATP(cycle repeats).
What is the process called when ATP form ADP and releases energy?
Hydrolysis.
Uses of the glucose made in the Calvin cycle.
+N, +S= amino acids
Starch
Other sugars
+P= phospholipids
Respiration
Triglycerides.
Why are enzymes that are involved the the LIS more affected by temperature?
Because they are free in the stroma so are not membrane bound.
Limiting factor definition.
The factor in the shortest supply for photosynthesis.
All photosynthesis limiting factors.
Light intensity
Light wavelengths
CO2 concentration
H2O concentration
Temperature.
Graph of CO2 concentration.
Rate of Ps increasing= CO2 is the limiting factor so rate of LIS is slow, specifically RuBP–> 6C
At a plateau= something else is LF
Rate starts to decrease= the stomata close to prevent CO2+H2O–> carbonic acid, would lower pH.
Graph of light intensity.
Rate increasing= is LF, specifically LDS, photoexcitation, photolysis, phosphorylation
Point where rate is highest= light saturation point, where more light has no effect on Ps
Plateau= something else is LF
Decreasing= pigments get bleached and damaged.
Graph of temperature.
Increasing= temperature is LF. higher temp= more kinetic energy= higher rate of enzymes
Peak= Optimum temperature
Decreasing= Ps enzymes have been denatured, affects LIS more as enzymes are free in the stroma and therefore less stable.
Light compensation point meaning.
Rate of Ps= rate of respiration
No net gas exchange.
Function of nitrogen and effects of deficiency.
Functions- synthesis of proteins, nucleic acids and chlorophylls
Deficiency= reduced growth of all organs, yellowing leaves(chlorosis).
Magnesium function and deficiency effects.
Function- chlorophyll production
Deficiency= yellowing of leaves(chlorosis).
Rf value calculation.
distance travelled by the pigment/ distance travelled by the solvent front.
