Required Practical 8

Question 1

What is the role of dehydrogenase enzyme in photosynthesis?

Answer 1

• catalyses production of NADP in LDR
• NADP accepts electrons from photoionisation of chlorophyll

Question 2

Describe how rates of dehydrogenase activity in chloroplasts can be measured

Answer 2

• extract chloroplasts from leaf
• set up A (control) with set volume of DCPIP, water and chloroplasts in isolation medium covered in FOIL
• set up B (control) with set volume of DCPIP, water and isolation medium
• set up C (standard) with water and chloroplasts in isolation medium
• set up D (experiment) with set volume of DCPIP, water and chloroplasts in isolation medium
• shine light onto test tubes and time how long it takes for DCPIP to turn colourless (reduced)
• rate = 1 / time taken