5.1 - Photosynthesis Flashcards
1
Q
Where does the light dependent stage occur?
A
in the thylakoid membranes/grana
2
Q
Where does the light independent stage occur?
A
stroma
3
Q
Describe photolysis
A
- chlorophyll absorbs light energy to split water into oxygen, H+ and e-
- H+ and e-s used to form NADPH for LIR
- e-s passed along electron transport chain
- O2 used in aerobic respiration or diffuses out through stomata
4
Q
Describe photoionisation
A
- light energy ‘excites’ electrons in chlorophyll, where they raise up an energy level
- some energy released conserved in the production of ATP and NADPH in chemiosmosis
5
Q
Describe chemiosmosis
A
- electrons move along series of proteins (ETC) releasing energy at each movement
- used to actively transport H+ ions across membrane from stroma into intermembrane space
- creates electrochemical gradient
- H+ ions diffuse through ATP synthase back into stroma
- causes ATP synthase to change in shape and energy released catalyses ATP synthesis (ATP later hydrolysed to release energy for LIR)
- H+ ion and electrons combine with co-enzyme NADP -> NADPH
6
Q
Describe the first stage of the Calvin Cycle (LIR)
A
Carbon fixation: CO2 ‘fixes’ RuBP into 2 molecules of GP
- catalysed by the enzyme rubisco
7
Q
Describe the second stage of the Calvin Cycle
A
GP is reduced to 2 molecules of triose phosphate using ATP and NADPH
8
Q
What is triose phosphate used for?
A
- to regeneration RuBP in Calvin Cycle
- converted to useful organic substances
9
Q
Describe the third stage of the Calvin Cycle
A
RuBP is regenerated using energy released from ATP hydrolysis
10
Q
Name the 3 factors which are limiting factors for photosynthesis
A
- temperature
- CO2 concentration
- light intensity
(see graphs - temperature is different to other two)
11
Q
How many turns of the Calvin cycle are required to produce 1 glucose per CO2?
A
6
