LDR Flashcards
What does the LDR produce?
- reduced NADP (NADPH)
- ATP
- Oxygen (by-product)
What is H2O split into in photolysis?
1/2 O2
2H+
2e-
What are the products of the LDR needed for?
LIR
What are the electrons produced in photolysis used for?
Replace the electrons lost in the chlorophyll
What are the H+ ions produced in photolysis used for?
picked up by NADP to make NADPH
also pumped to create electrochemical gradient and diffuse through ATP synthase (allowing ATP to be formed)
What causes chlorophyll to become ionised?
absorbs light energy, which raises energy level of electrons (excited state), causes them to leave chlorophyll
What happens to the electrons after they leave chlorophyll?
they are passed along an electron carrier chain in thylakoid membrane
What do the electrons passing through the chain do?
release/lose energy
What is the energy released by electrons passing through the electron carrier chain used for?
to pump H+ ions into the lumen of the thylakoid
What is created as H+ ions are pumped into the lumen of the thylakoid?
an electrochemical gradient
What are the 3 main steps of the LDR?
- photoionisation
- chemiosmosis
- photolysis
How are electrons passed along the electron carrier proteins?
in a series of redox reactions
What are the electrons used for after being passed along the electron transfer chain?
accepted alongside H+ to form NADPH
What is the energy lost from the electrons used for?
pumping H+ ions against their electrochemical gradient
What happens in photoionisation? (2 points)
- light absorbed by chlorophyll
- raises electrons an energy level SO they are lost from the chlorophyll
Why do plants benefit from having different coloured pigments?
absorb different/more wavelengths of light for the LDR
Why might not all light be used in photosynthesis?
- some could be reflected
- some light is incorrect wavelength
What happens in photolysis?
light energy absorbed by chlorophyll, splits H2O into 2H+ + 2e- + 1/2 O2
How is NADP reduced in the LDR?
- gains electrons from ETC
- originally from chlorophyll
If investigating photosynthesis, why would radioactively labelled carbon dioxide be used?
- involved/used in photosynthesis
- allows detection of products
What causes electrons to be lost from chlorophyll?
light energy
