5.2.1 Photosynthesis Flashcards
What parts of a chloroplast make it efficient for photosynthesis?
Large SA for max absorption
Thylakoids contain lots of pigments
Stroma is a chemical reaction site
What is the definition of a pigment?
Absorb different wavelengths of light
Why are leaves green?
Chlorophyll a pigment in stroma
Why is it good to have a range of pigments for photosynthesis?
- Each pigment absorbs different wavelengths of light
- Allows for a broader range of light to be absorbed
Where is chlorophyll B found?
The Thylakoids
What is the light dependent stage?
The first stage of photosynthesis where energy is harvested for light
What is the purpose of the light dependent stage?
To use energy to split water
To create ATP and NADPH
What are the four key steps of the light dependent stage?
- Non cyclic photophosphorylation
- Cyclic photophosphorylation
- Photolysis
- Chemiosmosis
Whuch photosystem is used first in non-cyclic photophosphorylation?
- Photosystem 2 at 680 nm
How are electrons moved along from photosystems in non cyclic phosphorylation?
Electron transport chain
How are electrons that are used up replaced in non cyclic phosphorylation?
Photolysis
What happens at the end of non cyclic photophosphorylation?
Electrons are accepted by NADP along with a H+ from photolysis forming NADPH
Which photosystem does cyclic photophosphorylation occur in?
Photosystem 1
How does cyclic photophosphorylation occcur?
Not all electrons are picked up by NADPH
What are the key differences between cyclic and non cyclic photophosphorylation?
Same electrons reenter system in cyclic photophosphorylation
No NADPH is made in cyclic photophosphorylation (some ATP is still made however)
What is the formula for Photolysis?
H2O -> 1/2O2 + 2e- + 2H+
What is the enzyme involved in chemiomosis?
ATP synthase
How are H+ ions transported via chemiosmosis?
As electrons move along electron transport chain they released small amounts of energy
This energy can then actively transport H+ out
What happens to the protons at the end of chemiosmosis?
Combine with NADP to form NADPH
Provide energy for photophosphorylation of ADP
Where does the light independent reaction occur?
In the stroma
What is the key enzyme involved in the calvin cycle?
RuBisCo
What are the reactants and products of the light independent reaction?
Reactants- Carbon dioxide, NADPH, RuBP and ATP
Products- Hexose sugar
How many cycles of the calvin cycle is it to form one hexose sugar?
6 cycles
What is the first step of the light independent reaction?
CO2 fixed to RuBP via RuBisCo to form 2x GP
WHat happens to GP in the calvin cycle?
Some reduced by NADPH to form TP
Others to form amino acids and fatty acids
Why is only one carbon removed from each turn of the cycle?
So that RuBP can be regenerated
