unit 5 photosynthesis

Question 1

Light Dependent Reaction –

Describe the process (6)

Answer 1

1. Excites electrons
2. Electrons move along electron transfer chain releasing energy
3. Energy used to join ADP and Pi to form ATP;.
4. Photolysis of water produces protons, electrons and oxygen;
5. NADP reduced by electrons and protons / hydrogen;

Question 2

Light Dependent Reaction. Describe

the electron transport chain (5)

Answer 2

1. Excites electrons (from chlorophyll); 2. Electrons move along electron transfer chain releasing energy;
2. Energy used to join ADP and Pi to form ATP;
3. Photolysis of water produces protons, electrons and oxygen;
4. NADP reduced by electrons;

Question 3

Light Independent Reaction.

Describe the Calvin Cycle (6)

Answer 3

1. Carbon dioxide combines with RuBP;
2. Produces two GP;
3. GP reduced to Triose Phosphate;
4. Using reduced NADP;
5. Using energy from ATP;
6. TP converted to glucose / hexose / RuBP /

Question 4

Why weedkillers cause plants to

give off heat? (2)

Answer 4

1. Energy is released from excited electrons
2. This energy which should be used to form ATP, cannot do this as the weedkiller blocks the ETC, (so the energy

Question 5

Why does increased light intensity

stimulate plant growth? (5)

Answer 5

1. Have faster production of ATP and reduced NADP;
2. (So) have more light-independent reaction;
3. (So) produce more sugars that can be used in respiration;
4. (So) have more energy for growth;
5. Have more synthesis of new organic materials;