5.1 Photosynthesis Flashcards
(26 cards)
What is photosynthesis?
The production of useful energy from light energy in a plant
What is the equation for Photosynthesis?
6CO2 + 6H2O + sunlight energy = C6H12O6 + 6O2
What are chlorophyll?
Pigments found in the chloroplasts in a plant. They absorb light and have different wavelengths. For example, chlorophyll a and chlorophyll b have affinities for red and blue lights.
Why is chlorophyll green?
They are green because we see the light which is reflected. They have a minimal affinity for green light because the sun emits a lot of green light. The inability to process this acts as a “sunscreen” to prevent over production in the plant.
What is photoionization?
Ionisation by light of a chlorophyll to release two e- into the electron transfer chain.
What is chemiosmosis?
The movement of ions across a semi-permeable membrane down an electrochemical gradient to produce energy
What is photolysis?
The splitting of water using light energy, specifically photons.
What are the adaptions of a leaf which allows successful photosynethisis.
Air spaces, waxy cuticle. xylem, thin upper epidermis, stomata, palisade layer.
What is oxidation?
The loss of electrons.
What is reduction?
The gain of electrons.
What is the Light Dependent Reaction?
Electron ONLY
Chlorophyll absorbs light energy
Two electrons are released and move to high energy levels.
Electrons are taken up by electron carriers and are transferred down the electron transfer chain, releasing energy as they move.
The energy which is released is used to make ATP
What is the Light Dependent Reaction?
Water ONLY
The electrons which are lost from the chlorophyll are replaced by electrons released during the photolysis of water, where oxygen is released as a bi product.
The water split into O2, H+ and e-
The electrons are used to replenish the chlorophyll
The H+ is used to reduce the NADP co enzyme carrier.
What is the Calvin Cycle?
The sequence of reactions that form the Light Independent Reaction.
Calvin Cycle:
Ribulose Bisphosphate + Rubisco +CO2
2 Glycerate 3 Phosphate
G3P
3 Carbons
Calvin Cycle:
2 Glycerate 3 Phosphate REDUCED
to 2 Triose Phosphate
3 Carbons
This is sometimes used to make other sugars, amino acids and lipids.
Calvin Cycle:
2 Triose Phosphate - 1Carbon
Ribulose Bisphosphate
RuBP
5 Carbons
Where does the LIR occur?
In the stroma of the chloroplats
Where does LDR occur?
The membrane of the Thylakoids.
What is happening to NADPH when G3P is being reduced in the Calvin Cycle?
NADPH from the LIR is a reducing agent as it is oxidised and forms NADP. This returns and replenishes LIR.
What is happening to ATP when G3P is being reduced in the Calvin Cycle?
ATP from the LIR is an oxidising agent as it is reduced and forms ADP. This returns and replenishes the LIR
What are the limiting factors of Photosynthesis?
[CO2]
T’
Light Intensity
How does CO2 affect the rate of photosynthesis?
Without CO2 RuBP cannot be converted into G3P
How does temperature affect the rate of photosynthesis?
Rubisco wont work at low T’ as theres not enough Ea
Rubisco is an enzyme and will denature if T’ is too high and break down.
Approx. rate doubles for every 10’ increase
How does light affect the rate of photosynthesis?
Light is needed in the LDR
The graph Rate/Light will plateau as other factors stop the rate
The more photons of the light; the more chlorophyll are ionised.
