Question
Biology Question on Photosynthesis in higher plants
The first carbon dioxide acceptor in C4-plants is
A
PEP (Phosphoenol pyruvate)
B
RuBP (Ribulose biphosphate)
C
Oxaloacetic acid
D
3-PGA (3-Phosphoglyceric acid)
Answer
PEP (Phosphoenol pyruvate)
Explanation
Solution
The primary acceptor of CO2, is a 3 carbon compound phosphoenol pyruvic acid. Addition of CO2, to any compound is called carboxylation. In C4 cycle, CO2, combines with phosphoenol pyruvic acid to form oxaloacetic acid. The enzyme is phosphoenol pyruvate carboxylase (PEPCo). The oxaloacetic acid breaks up into pyruvic acid and CO2, which combines with RUDP to form PGA as in Calvin cycle.