5.1 photosynthesis Flashcards
What is the overall equation of photosynthesis?
6CO2 + 6H2O ——> C6H12O6 + 6O2
What are the 2 stages of photosynthesis?
Light dependent and light independent
Where does the light dependent stage occur?
Thylakoid membrane
What is the first stage of photosynthesis?
Light dependent stage
What does the light dependent stage require?
Light
What happens in the photolysis of water?
- Light energy is absorbed by chlorophyll
- Splits water into oxygen, H+ and e-
What is the equation for the photolysis of water?
H2O —> 1/2O2 + 2e- + 2H+
What happens to the H+ produced in the photolysis of water?
The H+ is picked up by NADP to form NADPH
What happens to the e- produced in the photolysis of water?
The e- are passed along a chain of electron carrier proteins
What happens to the oxygen produced in the photolysis of water?
Either used for respiration or diffuses out of the leaf via the stomata
What is the photoionisation of chlorophyll?
- Light energy is absorbed by the chlorophyll
- Electrons are excited and move up an energy level to leave chlorophyll
- Chlorophyll is ionised by light
What happens when electrons have gained energy?
They move along a series of proteins embedded within the thylakoid membrane
What happens when the electrons move along the proteins in the membrane?
- They release energy
- Some energy is used to pump protons across the chloroplast membranes
What does moving protons across the chloroplast membranes do?
Creates an electrochemical gradient
How do protons move across the membrane?
They pass through the enzyme ATP synthase, producing ATP
What do the protons do once they have moved across the membrane?
Combine with the co-enzyme NADP to become reduced NADP (NADPH)
Where does the light independent reaction occur?
Stroma
What catalyses the light independent reaction?
RuBisCo
Where is RuBisCo found?
Stroma
Why is the light independent reaction temperature sensitive?
Because of the enzymes
What does the Calvin cycle do?
Uses CO2, NADPH and ATP to form a hexose sugar
What happens first in the Calvin cycle?
- CO2 reacts with RuBP to form GP
How many molecules of GP are formed when CO2 reacts with RuBP?
TWO
What is RuBP?
Ribulose biphosphate