Photosynthesis

Question 1

Light Stage: Pathway 1

Answer 1

The electrons leave the electron acceptor and then pass through a series of other electron acceptor.
As they do they lose some of their energy and it will be used to form ATP from ADP + P
(Note phosphorylation means addition of phosphate to ADP)
Cylcic flow returns to chlorophyll

Question 2

The Stages in Photosynthesis

Answer 2

Light Stage

Dark Stage

Question 3

Water is split

Answer 3

Step 2
Energy us used to split water molecules into 2 hydrogen ions, 2 electrons and 1/2 oxygen molecule.
H2O -> 2H + 2e + 1/2O2

Question 4

Light Stage: Pathway 2

Answer 4

The electron pass through a series of electron acceptors
They lose their energy as they pass fromone acceptor to the next.
The energy is used to form ATP from ADP + P
These electrons do not return to chlorophyll but instead are picked up by NADP+ (NADP+ + 2e- -> NADP-
Water splits = photolysis
2H2O -> 4H+ + 4e- + O2
The H+ is picked up by NADP-
NADP- + H+ -> NADPH
The electrons from the splitting of water will be passed to chlorophyll to replace the one that didn’t go back

Question 5

Role of photosynthesis

Answer 5

Used to make food for plant
Food is eaten by animals + passed on in food chain
Oxygen is produced 
Formation of fossil fuels
Removes CO2

Question 6

The fate of the products from the splitting water

Answer 6

Step 3
Electrons passed onto chlorophyll
Hydrogens stored for later use + become part of the carbohydrate produced
The oxygen can be used by the plant in respiration or released into the atmosphere

Question 7

Light stage (overview)

Answer 7

Light dependent reaction
No enzymes required (quick reaction)
Located in chloroplasts (in stacks)
Produces ATP, NADPH, Oxygen

Question 8

Dark Stage/ Light independent stage

Answer 8

Carbon dioxide is reduced (addition of hydrogen) and glucose is formed
The NADPH will supply the hydrogen
The ATP will supply the energy

Question 9

Energised Electrons

Answer 9

Step 4

The energy trapped in the chlorophyll is passed onto electrons making them become high energy electrons

Question 10

Glucose formation

Answer 10

Step 5

The high energy electrons, the hydrogen ions and the carbon dioxide combine to make glucose

Question 11

Dark Stage (overview)

Answer 11

Light independent reactions
Needs light stage's products
Requires enzyme's (slow reaction)
In fluid part of chloroplasts
Produces NADP+, ADP, P, Glucose

Question 12

Light is absorbed

Answer 12

Step 1
Sun’s energy is trapped in green pigment - chlorophyll in the choloplast
This will provide the energy needed to make glucose

Question 13

Equation for Photosynthesis

Answer 13

6CO2 + 6H2O -Sun+Chlorophyll–> C6H12O6 + 6O2

Question 14

Steps in Photosynthesis

Answer 14

Light is absorbed
Water is split
The fate of the products from the splitting water
Energising Electrons
Glucose formation

Question 15

Factors needed for photosynthesis

Answer 15

Carbon dioxide
Water
Sunlight
Chlorophyll