RP8-dehydrogenase activity in chloroplasts

Question 1

what is the function of dehydrogenase in the chloroplasts

Answer 1

-catalyses the acceptance of electrons by NADP in the light dependent reaction

Question 2

what is the purpose of DCPIP

Answer 2

-redox indicator dye and act as alternate electron acceptor instead of NADP
-turns from blue to colourless when reduced

Question 3

why is the plant extract chilled in an ice-bath

Answer 3

-to reduce the enzyme activity to prevent them from breaking down the chloroplasts

Question 4

how is the control set up

Answer 4

fill up a cuvette with distilled water and chloroplast extract

Question 5

how is light intensity controlled

Answer 5

-adjust the distance of the lamp from the set up
-perform the practical in the dark so that the lamp is the only light source

Question 6

what is the function of the muslin cloth

Answer 6

-filter out any debris but allows any chloroplasts to pass through

Question 7

why are the stalks removed from the plant before using a pestle and mortar

Answer 7

-the stems do not contain many chloroplasts

Question 8

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

Answer 8

-set colorimeter to the red filter and zero it using a cuvette containing distilled water and chloroplast extract
-place test tube in the rack 30cm away from light source and add DCPIP
-immediately take a sample and measure its absorbance
-take another sample and measure its absorbance every 2 minutes for 10 minutes
-repeat for different distances from lamp up to 100cm