RP8 Dehydrogenase Activty In Chloroplast

Question 1

What is the function of dehydrogenase in chloroplasts?

Answer 1

It catalyses the acceptance of electrons by NADP in the light dependent reaction.

Question 2

What is the purpose of DCPIP?

Answer 2

• its a redox indicator dye and acts as an alternate electron acceptor instead of NADP.
• it runs blue to colourless when reduced.

Question 3

Why is the plant extract chilled in an ice-water bath?

Answer 3

To lower activity of enzymes to prevent them from breaking down the chloroplast’s.

Question 4

How is the control set up

Answer 4

Fill e cuvette with chloroplast extract and distilled water.

Question 5

How is light intensity controlled?

Answer 5

• adjust the distance of the lamp front he set up
• perform practical in a dark room so that the only light source is the lamp.

Question 6

What is the function of the muslin cloth?

Answer 6

To filter out any debris in the ground leaf mixture but allowing chloroplast to pass through.

Question 7

Why are the stalk of leaves removed before grinding.

Answer 7

The stalk don’t contain many chloroplasts

Question 8

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

Answer 8

1. Set the colorimeter to the red filter. Zero using a cuvette containing chloroplast extract and distilled water.
2. Place test tube in the rack 30cm from light source and add DCPIP. Immediately take a sample and add to cuvette. Measure the absorbance of the sample.
3. Take a sample and measure its absorbance every 2 minutes for 10 minutes.
4. Repeat for different distances from lamp up to 100 cm.