Unit 3.3: Photosynthesis

Question 1

What is the equation for photosynthesis?

Answer 1

Carbon dioxide + water = Glucose + oxygen

Question 2

What happens to the wavelengths absorbed by the chlorophyll?

Answer 2

It excites the chlorophyll which in turn excites the electrons. These can be used in electron transport chains to drive ATP synthase to make ATP

Question 3

What is the first stage of photosynthesis?

Answer 3

• Called photolysis
• Takes place in the Granum
• Water is broken down - oxygen is released as a by-product
• Hydrogen and electrons are picked up by NADP to form NADPH
• ATP and NADPH are carried to the second stage

Question 4

What is the second stage of photosynthesis?

Answer 4

• Called the Calvin cycle
• Takes place in the stroma
• Carbon dioxide enters the cycle attaches to RuBP by the enzyme RuBisCO to produce 3PG.
• The 3PG that is produced is phosphorylated by ATP and combined with hydrogen from NADPH to form G3P
• G3P is used to either regenerate RuBP or can be used to synthesise sugars, for example glucose.