RP08 - Dehydrogenase activity in chloroplast

Question 1

What is the function of dehydrogenase in chloroplast

Answer 1

• It catalyses the acceptance of electrons by NADP in LDR

Question 2

What is the purpose of DCPIP

Answer 2

• It is a redox indicator dye and acts as an alternate electron acceptor instead of NADP
• It turns from blue to colourless when reduced

Question 3

Why is plant extract chilled in a plant water bath?

Answer 3

Lowers enzyme activity, preventing them from breaking down chloroplast

Question 4

How is the control set up

Answer 4

Fill a cuvette with chloroplast extract and distilled water

Question 5

How is light intensity controlled

Answer 5

• Adjust the distance of the lamp from the set-up
• Perform the practical in a dark room so that the only light source is the lamp

Question 6

What is the function of muslin cloth?

Answer 6

• To filter out any debris in the ground lead mixture but allowing chloroplast to pass through

Question 7

Why are stalks of leaves removed before grinding

Answer 7

The stalks don’t contain chloroplast

Question 8

Outline the procedure of the investigating the effect of light intensity after chloroplast extract has been obtained

Answer 8

1. Set the colorimeter to red filter. Put it on zero using the cuvette with chloroplast and distilled water.
2. Place test tube rack 30cm from light source and add DCPIP. Immediately take sample and add to cuvette Measure absorbance
3. Take a sample and measure its absorbance every 2 mins for 10 mins
4. Repeat for different lamp distances