Use Figure 8.2 and the compounds labeled A, B, C, D, and E to answer the following questions.
Figure 8.2
-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? Study Figure 8.2 to help you in determining the correct answer.

Question

Use Figure 8.2 and the compounds labeled A, B, C, D, and E to answer the following questions.
  Figure 8.2
-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? Study Figure 8.2 to help you in determining the correct answer.

Quizplus · Accepted Answer

If CO2 is cut off, the concentration of the CO2 acceptor will increase until it reaches saturation. If light is cut off, the production of ATP and NADPH will decrease, so the concentration of the CO2 acceptor will decrease. Choice C correctly identifies that the CO2 acceptor concentration would increase when the CO2 is cut off, but decrease when the light is cut off.