Which molecule would first contain ¹⁴C if the alga Chlorella was grown in the presence of light and radioactive CO₂?

A. Glycerate 3-phosphate
B. Glucose
C. Rubisco
D. Ribulose bisphosphate (RuBP)

A

Teachers complained that this was a tricky question. Most candidates chose the correct answer of G3P, but some believed that RuBP was the first to contain radioactive carbon. The major complaint was that in the question the fact that ¹⁴C was radioactive was not stated in the question. This is in the guide, so part of the testing required candidates to infer this from the question.