A student investigates the Hill reaction using isolated spinach chloroplasts and the dye DCPIP, which is blue when oxidized and colorless when reduced. The chloroplast suspension is mixed with DCPIP in cuvettes that are placed at distances of 10, 20, 40, and 80 cm from a light source. Absorbance at 600 nm is measured every 30 seconds for 5 minutes. A "boiled chloroplast" cuvette and a "no chloroplast" cuvette serve as controls. The student plots absorbance versus time for each treatment.
What is the function of the boiled chloroplast control?
- A
To test whether boiling produces oxygen
- B
To increase the rate of the Hill reaction
- C
To measure background absorbance of DCPIP without illumination
- Dcheck_circle
To verify that DCPIP reduction requires functional photosynthetic membranes
Explanation
Boiling denatures photosystem proteins. If boiled chloroplasts fail to reduce DCPIP, the experimenter has shown that intact, functional photosynthetic machinery, not nonenzymatic chemistry, is responsible for DCPIP reduction in the experimental tubes.