Photosynthesis Flashcards
What is the equation for photosynthesis?
6CO2 + 6H2O → C6H12O6 + 6O2.
Define what a autotroph is?
Autotroph is an organism that can produce organic molecules from inorganic molecules such as light, water, CO2 or other chemicals
Name the components in chloroplasts?
-granum(stack of thylakoids)
-Stroma
-thylakoid membranes
-intergranal lamella
-outer membrane
-inner membrane
Define what a Heterotrophs is?
A organism that eats other plants and animals for energy and nutrients- obtaining complex molecules
What does the light harvesting system include? what is its role?
The light harvesting system (antennae complex) has:-
Primary pigment-chlorophyll a
Accessory pigments- chlorophyll b, xanthophylls and carotenoids.
The role of the system is to absorb or harvest, light energy of different wavelengths and transfer this energy quickly and efficiently to the reaction centre.
what is a photosystem, Where is it?
The light harvesting system and reaction centre is known as a photosystem which absorb different wavelengths of light which is needed for photosynthesis- are in the thylakoid membranes.
Briefly summarise non-cyclic photo phosphorylation
- Light hits PSII
- Two electrons are excited- PSII is electron deficient
- Electrons pass down electron transport chain- ATP is produced
- Light hits PSI
- PSI releases two electrons- electrons from PSII replace the ones lost from PSI
- Electrons are again passed down electron carrier chain- ATP is produced
- The electrons are are used to reduce NADP to NADPH
The products produced are ATP and reduced NADP- used in light independent stage.
Name the products of the light-dependent stage of photosynthesis?
-Reduced NADP
-ATP
-Oxygen
These products are used in light-independent stage of photosynthesis
What is photolysis?
the separation of H2O using light which produces hydrogen ions, electrons and oxygen.
H2O→ 2 e– + 2 H+ 1/2 O2
- electrons released are used to replace the electron deficient PSII in photo-phosphorylation.
How does cyclic photophosphorylation differ from non cyclic?
Cyclic photophosphorylation only occurs in the PSI whilst non-cyclic is in both PSll and PSI. In cyclic only ATP is produced but no reduced NADP is produced this only occurs in non cyclic.
Where does the light independent stage take place?
Takes place in the stroma of chloroplast
Briefly explain the Calvin cycle?
- CO2 enters the intercellular spaces within the spongy mesophyll
- diffuses into the stroma where it is conbined with 5 carbon molecule- RuBP(Ribulose bisphosphate)
- CO2 and RuBP with the help of the enzyme RuBisCO (ribulose biphosphate carboxylase)
produce a unstable 6 carbon molecule-FIXATION STAGE - 6C molecule immediately breaks down and forms 3 carbon 2 x GP (gylcerate 3-phosphate) molecule
- 2 x GP is converted to another 3C molecule 2 x TP using reduced NADP and ATP from LDP - REDUCTION STAGE
- TP ( triose phosphate) is a carbohydrate it is recycled to make more RuBP-REGENERATION STAGE
What is the Regeneration Of RuBP?
One glucose molecule is produced when six CO2 molecules enter the Calvin cycle producing 12 TP molecules from 6 cycles- two TP are used to produce glucose and the other 10 are recycled to give 6 RuBP molecules - ATP is used as a energy source in this reaction.
What factors effect the rate of photosynthesis?
Light intensity- if light intensity increases, ATP and NADPH are produced at a higher rate.
CO2 concentration- increases the rate of carbon fixation in the Calvin cycle- higher rate of TP production.
Temperature- increases the rate of enzyme activity
What is the effect of light intensity on the Calvin cycle?
If light intensity is decreased it will reduce the rate of the light- dependent stage of photosynthesis- reducing the quantity of ATP and NADPH produced which convert GP to TP therefore the concentration of TP will decrease- as a result RUBP will decrease.
The reverse happens when light intensity is increased.
