Use the Accompanying Figure and the Molecules Labeled A, B

Multiple Choice

Use the accompanying figure and the molecules labeled A, B, C, D, and E to answer the following questions. Refer to the figure. To identify the molecule that accepts CO2, Calvin and Benson manipulated the carbon-fixation cycle by either cutting off CO2 or cutting off light from cultures of photosynthetic algae. They then measured the concentrations of various metabolites immediately following the manipulation. How would these experiments help identify the CO2 acceptor?

A) The CO2 acceptor concentration would decrease when either the CO2 or light is cut off.
B) The CO2 acceptor concentration would increase when either the CO2 or light is cut off.
C) The CO2 acceptor concentration would increase when the CO2 is cut off but decrease when the light is cut off.
D) The CO2 acceptor concentration would decrease when the CO2 is cut off but increase when the light is cut off.
E) The CO2 acceptor concentration would stay the same regardless of the CO2 or light.