Light Dependent Reactions

Question 1

where does LDR occur

Answer 1

LDR occurs on thylakoid membrane in chloroplast

Question 2

LDR

Answer 2

Chlorophyll in PSII absorbs light energy which excites electrons to a higher energy level, releasing them from chlorophyll (photoionisation).
Some energy from electrons released is conserved in the production of ATP and reduced NADP

Question 3

Production of ATP

Answer 3

1) electrons pass down Electron Transfer chain (ETC) from PSII to PSI via redox reactions, losing energy at each step

2)This energy is used to actively transport protons from Stroma into Thylakoid

3) This creates an electrochemical gradient across the thylakoid membrane

4)Protons move by facilitated diffusion down the electrochemical gradient into the stroma via the enzyme ATP synthase embedded in the thylakoid membrane

5) energy from this allows ADP+Pi—> ATP (photophosphorylation) This is called the chemiosmotic theory

Question 4

Production of NADP

Answer 4

In PSI electrons are exicited and transferred to NADP to reduce NADP to form reduced NADP

Question 5

what happens during photolysis

Answer 5

Splitting of water using light energy which produces protons, electrons and oxygen

2H2O—–> O2+4e- + 4H+

The electrons from this are used to replace those lost from the chlorophyll.

Question 6

Products of the LDR

Answer 6

ATP and Reduced NADP (used in LIR)
Also oxygen which leaves the cell as a by product or used in respiration