LDR Flashcards
Where does the Light dependent reaction happen?
In the membranes of the thylakoids inside chloroplasts.
What happens to the chlorophyll when it absorbs light energy?
The electrons become excited, raising their energy level and are released from the chlorophyll and accepted by the electron carriers in the electron transport chain. This is photoionisation.
Where do the electrons come from to replace the ones lost to the etc?
The photolysis of water to make O2, H+ ions and electrons
What is the energy from the transport of electrons along the chain used for?
Pumping hydrogen ions into thylakoid
What happens to the electrons after they are taken into photosystem I?
Light energy are excited again to an even higher level and are transferred to NADP along with a H+ ions, forming reduced NADP
How is an electrochemical gradient used to generate ATP?
ATP production occurs when hydrogen ions (protons) diffuse down an electrochemical gradient through molecules of the enzyme ATP synthase which changes the shape of ATP synthase causing the production of ATP. The movement energy is transferred to chemical energy in the phosphate bond of ATP.
What is chemiosmotic theory?
The process of hydrogen ions moving across the thylakoid membrane, into the stroma down the electrochemical gradient, driving the production of ATP.
What is NADP?
The coenzyme used to photosynthesis to transfer hydrogen from the LDR to the LIR
What are the products of the LDR?
ATP and reduced NADP
What is meant by the term photophosphorylation?
Light is absorbed by chlorophyll and this is linked to the production of ATP by the phosphorylation of ADP with an inorganic phosphate.
What is meant by the term photoionisation
Light energy is absorbed by chlorophyll. The electrons become excited, raising their energy level and are released from the chlorophyll and accepted by the electron carriers in the electron transport chain. The chlorophyll has therefore been ionised (lost electrons).
What is a photoautotroph. Give examples.
Organisms that make their own organic molecules such as glucose from inorganic molecules such as carbon dioxide. Plants, algae and some species of bacteria are photoautotrophs.
Why does the process of photosynthesis give indirect evidence of evolution?
It is the same in all photoautotrophic organisms e.g. plants, algae, some species of bacteria.
