photosynthesis

Question 1

what are the 2 stages of photosynthesis?

Answer 1

• the light dependant reaction
• the light independent reaction

Question 2

where does the LDR occur ?

Answer 2

in the thylakoid membranes or grana

Question 3

where does the LIR occur ?

Answer 3

the stroma

Question 4

the light dependent reaction - photoionisation

Answer 4

• chlorophyll absorbs light.
• this causes electrons to become excited and move up an energy level to leave the chlorophyll.
• leading to the photoionisation of chlorophyll

Question 5

the light dependent reaction - production of ATP and reduced NADP

Answer 5

some of the energy from electrons released during photoionisation is used for the production of ATP and reduced NADP in chemiosmosis.

Question 6

the light dependent reaction - chemiosmosis

Answer 6

• production of ATP involves the movement of electrons along the electron transport chain.
• as electrons move along the ETC, they release energy which is then used to actively transport protons (H+) across the membrane from the stroma into the intermembrane space, resulting in a high concentration of protons in the intermembrane space.
• protons then move down the concentration gradient back into the stroma through the enzyme ATP synthase, producing ATP.
• some of the protons that have been pumped back into the stroma combine with coenzyme NADP to become reduced NADP.

Question 7

the light dependent reaction - photolysis

Answer 7

photolysis of water produces protons, electrons and oxygen

Question 8

the light independent reaction- process

Answer 8

• carbon dioxide combines with ribulose bisphosphate to form 2 molecules of glycerate 3-phosphate (3C).
• glycerate 3-phosphate is then reduced to triose phosphate using ATP, and by accepting a H+ from reduced NADP.
• some of the carbon from triose phosphate leaves the cycle to be converted into useful organic compounds.
• the rest of the triose phosphate is then used to regenerate ribulose bisphosphate