11.3 — light dependant reaction

Question 1

where does the light-dependent reaction occur?

Answer 1

in the thylakoid membranes inside chloroplasts

Question 2

what are the adaptations from the thylakoids for light-dependent reactions?

Answer 2

1. large surface area — so they can contain more chlorophyll and electron carriers
2. ATP synthase channels — this allows the synthesis of ATP
3. selectively permeable — this allows a proton gradient to be set up

Question 3

how is a large surface area in the thylakoid membranes an adaptation for light-dependant reaction

Answer 3

so they can contain more chlorophyll and electron carriers

Question 4

how is a ATP synthase channels in the thylakoid membranes an adaptation for light-dependant reaction

Answer 4

this allows the synthesis of ATP

Question 5

how is the thylakoid membrane being selectively permeable membrane adaptation for light-dependant reaction?

Answer 5

this allows a proton gradient to be set up up

Question 6

what does the light-dependent reaction use?

Answer 6

water and light energy

Question 7

what does the light-dependent reaction produce

Answer 7

ATP, reduced NADP and oxygen (as a by-product)

Question 8

what is another name for the light-dependant reaction and why?

Answer 8

photophosphorylation, as it is the process by which ATP is formed using light energy

Question 9

what are the four stages of the light-dependant reaction?

Answer 9

1. absorption of light energy and photoionisation
2. electron transfer along the electron transport chain
3. photolysis of water
4. chemiosmosis

Question 10

what is the diagram of the light-dependent reaction?

Answer 10

draw it

Question 11

how does absorption, photoionisation and the transportation of electrons take place in the light-dependant reaction?

Answer 11

1. light energy is absorbed by pigments
2. photoionisation occurs, which is when these electrons are excited and lost from the pigments (where the pigments are oxidised)
3. electrons are transferred to an electron carrier molecule (the electron carrier is reduced)
4. electrons are passed alone the electron transport chain, releasing energy as they go

Question 12

what is the first stage of the light dependent reaction?

Answer 12

the absorption of light energy and photoionisation

Question 13

what is the second stage of the light dependent reaction?

Answer 13

electron transfer along the electron transport chain

Question 14

what is the third stage of the light dependent reaction?

Answer 14

photolysis of water

Question 15

what is the fourth stage of the light dependent reaction?

Answer 15

chemiosmosis

Question 16

what are the four stages of photolysis?

Answer 16

1. light is used to split water into electron, protons and oxygen:

2H₂O -> 4H⁺ + 4e^- + O₂

2. the electrons replace those lost from pigments during photoionisation
3. the protons are used for ATP production and combine with electrons to reduce NADP
4. oxygen gas is released as a by-product