Question

Radioactive $C^{14}$ is given to $C{0}_2$ and released to atmosphere. This $C{0}_2$ is taken by ribulose diphosphate in a $C_3$plant. First radioactive$C^{14}$ is seen in which compound?

• A. PGAL
• B. PEP
• C. RMP
• D. PGA

Answer 1

The correct option is D PGA

$C^{14}$ an isotope of carbon, has been used to draw the path of $C{0}_2$ fixation in Kelvin cycle.This labelled $C^{14}$becomes incorporated with ${}^{14}C{O}_2$ which is accepted by RuBP and a 3-C compound phosphoglyceric acid (3 PGA) is formed, PGA is the first stable compound.