Investigating the light dependent reaction

Question 1

Outline a method to investigate the light dependent reaction

Answer 1

1) Grind green leaves in ice cold sucrose solution
2) Centrifuge to obtain chloroplast pellets and supernatant
3) Store leaf extract in ice-cold water bath
4) Set up different condition test tubes
5) Add DCPIP and time how long it takes to decolourise

Question 2

Which tube has the highest absorption?

Answer 2

Leaf extract, DCPIP, light

Generates electrons in the LD reactions, causing DCPIP to decolourise and reveal the green colour of the chloroplasts

Question 3

Which tube has the lowest absorption?

Answer 3

Leaf extract, distilled water

Question 4

What is in the isolated medium?

Answer 4

Sucrose and KCl in phosphate buffer

Question 5

What does DCPIP act as?

Answer 5

An electron acceptor

Question 6

What colour does DCPIP go as it accepts electrons and becomes reduced?

Answer 6

Blue to colourless

Question 7

What is the role of sodium hydrogencarbonate?

Answer 7

Provides CO2