Spinach chloroplasts are mixed with DCPIP and illuminated at four distances (10, 20, 40, 80 cm). Light intensity follows the inverse-square law. The graph shows absorbance (at 600 nm) versus time. Lower absorbance indicates more DCPIP has been reduced.
Which conclusion is best supported by the data?
- A
Boiled chloroplasts reduce DCPIP fastest
- Bcheck_circle
The rate of the Hill reaction increases as light intensity increases
- C
Distance from light source has no effect on photosynthesis
- D
DCPIP reduction occurs only in the dark
Explanation
The cuvette closest to the light (10 cm, highest intensity) shows the steepest drop in absorbance, meaning DCPIP is reduced fastest. As distance increases, intensity decreases (inverse-square law) and the rate decreases.