Photosynthesis (Part 2 - Light Phase and Dark phase)

Question 1

Light phase

Answer 1

Light dependant
Sunlight energy is trapped by chlorophyll and used to make ATP
H2O is split into H+ and O2 then H+ is used to make NADPH

Question 2

Where does the light phase occur

Answer 2

In the granum of the chloroplast (thylakoid membrane)

Question 3

Products of the light phase

Answer 3

O2 - waste gas or used in respiration
ATP - Used in dark pahse to provide energy to make glucose
NADPH - used in dark phase to transfer hydrogen and electrons to glucose

Question 4

Light phase - Pathway 1 (Cyclic pathway)

Answer 4

Light hits chloropyll
Light energy is absorbed by chloropyll’s electrons and these high-energy electrons break free
Electrons passed along a system of electron carriers
The energy lost at each step is trapped by the ATP

Question 5

Light phase - Pathway 2 (Non-cyclic pathway)

Answer 5

Light hits chloropyll
Light enrgy is absorbed by chlorophyll’s electrons and these high-energy electrons break free from the chlorophyll molecule
Chlorophyll is short of electrons and takes electrons from H2O
H2O is split into electrons H+ ions (create a proton pool) and O2 - This is called photolyisis (splitting of water using light)
Passed along a system of electron carriers
Electrons lose energy are picked up by NADP+
NADP+attracts a H+ ion from the proton pool and becomes NADPH

Question 6

Dark Phase

Answer 6

Light independant
Occurs in the stroma of the chloroplasts
Glucose is produced using CO2

Question 7

Products of the dark phase

Answer 7

Glucose - Stored as starch
              - Used in respiration
              - Used to make lipids and proteins
ADP + P - Reused in the light phase
NADP+   - Reused in the light phase

Question 8

Dark Phase process

Answer 8

NADPH ———–> NADP+ ———> Light phase
-
H+ electrons
-
6CO2 —————————->C6 H12 06
- (glucose)
energy
-
ATP ————-> ADP + P ————-> Light phase