Unit 5 Photosynthesis

Question 1

Where and what is the light dependent reaction

Answer 1

It happens in the thylakoid membrane and it used light energy and water to form ATP and NADPH

Question 2

Summarise the stages of light dependent reaction

Answer 2

Photolysis
Photoionisation of chlorophyll
Chemiosmosis (ETC) - ATP production
NADPH

Question 3

What is photolysis

Answer 3

Light energy used to split water into electrons, protons and oxygen

Question 4

What is Photoionisation

Answer 4

The light energy excites the electrons, this causes the electron to leave cell so the chlorophyll has been oxidised (lost an electron)

Question 5

What happens in Chemiosmosis (mention the ETC)

Answer 5

• Once the electron has been excited(oxidised) it’s transported through ETC, releasing energy
• this energy is used to pump protons through plasma membrane (from stroma to thylakoid)
• these protons then diffuse back through the ATP synthase where they release energy used to make ATP from ADP+Pi

Question 6

How is NADPH formed

Answer 6

Electrons/ Protons from water are accepted by NADP forming NADPH(reduces NADP)

Question 7

What are the products of light dependent reaction

Answer 7

ATP

NADPH

Question 8

Where and what is the light independent reaction

Answer 8

It occurs in the stroma

Question 9

What happens in the first stage of the light independent reaction

Answer 9

RuBP(5C) combines with carbon dioxide(1C) to form GP(3C) this is catalysed by the enzyme Rubisco

Question 10

What happens after GP is formed

Answer 10

ATP is used to provide energy for the reduction of GP to TP (using NADPH ➡️NADP)

Question 11

What’s is Triose phospahte (TP) used for

Answer 11

Is used to make hexose sugars ( used for respiration, energy for active transport…) and regenerate RuBP