light dependent reaction

Question 1

what is the first part of LDR?

Answer 1

non-cyclic phosphorylation

Question 2

summarise the process of non-cyclic phosphorylation

Answer 2

• PS II pigments absorb light at 700nm
• absorbed light excites and releases electrons
• electrons move along transport chain to PS I
• electrons lose energy by chemiosmosis and this converts ADP to ATP
• electrons lost from PS II are replaced by e- from photolysis
• electrons lost from PS I are combined with H+ and accepted by NADP coenzyme to form reduced NADP

Question 3

summarise the process of cyclic phosphorylation

Answer 3

• some e- released by PS I are not picked up by NADP
• they are recycled back to PS I
• electrons release energy which leads to chemiosmosis

Question 4

summarise the process of chemiosmosis

Answer 4

• electrons which gained energy move along thylakoid membrane proteins
• electrons release energy and pump H+ which creates an electrochemical gradient and produces ATP
• H+ and NADP form reduces NAD

Question 5

summarise the process of photolysis

Answer 5

• light absorbed by chlorophyll splits H2O
• O2 is a byproduct
• 2 e- 2H+ and O2 form
• H+ is pumped into thylakoid space and returns to stroma for conversion of ATP