Photosynthesis

Question 1

photosynthesis

Answer 1

the way plants make their own food using light energy from the sun

Question 2

balanced chemical equation for photosynthesis

Answer 2

6CO2 + 6H2O + light = C6H12O6 +6O2

Question 3

location of photosynthesis

Answer 3

chloroplast

Question 4

role

Answer 4

plants use it to make food
animals get their food from plants
it produces oxygen which is needed in respiration to release energy (ATP)

Question 5

why plants are green

Answer 5

colours of light absorbed, but green and yellow are reflected

Question 6

stages

Answer 6

light stage
pathway 1 or 2
dark stage

Question 7

end products of light stage

Answer 7

ATP- provide energy for dark stage
NADPH- provide protons and energised electrons for dark stage
Oxygen- released into atmosphere/respiration

Question 8

end products of dark stage

Answer 8

Glucose- used in respiration or stored in leaf as starch
ADP+P- return to light stage to pick up energy
NADPH- return to light stage to pick up H+ ions and electrons

Question 9

ATP stands for

Answer 9

adenosine triphosphate

Question 10

light stage pathway 1 cyclic

Answer 10

1. electron contained in chlorophyll absorb light energy and become high energy
2. electron loses energy as it moves from electrons acceptor to electron acceptor
3. energy lost is picked up by ADP+P to form ATP+ water
4. low energy electron returns to chloropyll
   product: ADP

Question 11

light stage pathway 2 non cyclic

Answer 11

1. Photolysis- H+ ions stored in proton pool
   oxygen is released into atmosphere/used in respiration
   2e- stored in chlorophyll
2. 2e- energised from the sun
3. 2 high energy e- move through a series of acceptors
   energy is lost and picked up by ADP, forming ATP
   4.2e- do not return to chlorophyll, instead 2e- pass along e- acceptors to combine with NADP+ forming NADP-
   protons in pool are attracted to NADP-, forming NADPH
4. chlorophyll molecule now has no e-, gains more from photolysis

Question 12

photolysis

Answer 12

splitting of water

h20 = 2H+ + 2e- + 1/2 O2

Question 13

dark stage

Answer 13

known as light independent stage, does not need light to occur
location: chloroplast, stroma
controlled by enzymes and therefore can be affected by temperature

Question 14

outline the dark stage

Answer 14

1. CO2 enters chloroplast
2. CO2 provides carbon atoms for its reduction to glucose
3. ATP provides energy
4. NADPH provides H+ ions and electrons for its reduction of CO2 to glucose