11.2 the light- dependent reaction

Question 1

explain how ATP is made during the light-dependent reaction. (6)

Answer 1

• H⁺ pumped from the stroma to thylakoid membrane
• using protein carriers
• energy provided from electrons from photolysis of water
• protons from photolysis also increases concentration gradient
• H⁺ goes down concentration gradient through ATP synthase channel proteins
• catalyses ADP+Pi→ ATP

Question 2

what is oxidation?

Answer 2

• loss of electrons
• loss of hydrogen
• gain of oxygen

Question 3

what is reduction?

Answer 3

• gain of electrons
• gain of hydrogen
• loss of oxygen

Question 4

describe the role of photolysis in the light-dependent reaction. (6)

Answer 4

• light excites electrons
• electrons go down electron transfer chain
• energy is releases
• ADP+ Pi form ATP
• NADPH from H⁺+ NADP
• from photolysis

Question 5

write the equations for the photolysis of water.

Answer 5

2H₂O→4H⁺+4e⁻+O₂

Question 6

explain how chloroplasts are adapted to carry out the light-dependent reaction. (4)

Answer 6

• thylakoid membranes -> large SA for the attachment of chlorophyll, electron carriers and enzymes that carry out LDR
• proteins in grana hold chlorophyll in precise way to allow maximum absorption
• granal membranes have ATP synthase channels to produce ATP
• chloroplasts contain both DNA and ribosomes so they can quickly and easily make proteins for LDR