Photosynthesis

Question 1

Light dependent reaction (3 points)

Answer 1

1. Involves light, make atp, reduced NADP, oxygen (by product)
2. Series of oxidation-reduction reactions (redox)
   3.

Question 2

Light dependent reaction

Sequence

Answer 2

1. Chlorophyll molecule absorbs light energy, excites 2 electrons
2. Proton pump gains electrons, reduction (thylakoid membrane)
3. Reduced proton pump actively transport H+ from stroma into thylakoid space
4. Creates electrochemical gradient between thylakoids space and stroma
5. Electrons are transported from proton pump (oxidation) to etc (reduction)
6. Electrons are passed along etc series of redox reactions
7. Each new carrier lower energy level than previous, electrons lose energy, some energy used to make ADP+Pi=ATP
8. Protons diffuse down electrochemical conc gradient through ATP synthase. Enzyme catalyse ADP to ATP
9. Photolysis of water
   - occurs in thylakoid space
   - replenishes chlorophyll 2e
   - adds to H+ electrochemical gradient
   - produces O2 as by product

Question 3

Light independent reaction

3 points

Answer 3

• requires products from light dependent reaction- atp reduced to nadp
• no light
• stroma

Question 4

Light independent reaction

Calvin cycle

Answer 4

Series of reactions producing organic compounds a pant needs e.g glucose

1. CO2 diffuses into leaf into stroma
2. Enzyme rubisco catalyses the reaction of Ribulose Biphosphate (Rubp) (5c) and CO2 into 2X glycerate 3 phosphate (GP)
3. Reduced NADP from LDR reduced glycerate 3 phosphate into 2 x triode phosphate (TP) (3c) using energy from ATP
4. NADP is re-formed returned to LDR
5. Some tries phosphate is converted into organic substances e.g glucose
6. Most TP used to regenerate RuBP using ATP from LDR

Produce 1 glucose= reaction needs to take place 6 times