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Which is the first $CO_2$ acceptor enzyme in $C_4$ plants :
A
RuDP carboxylase
B
Phosphoric acid
C
RUBISCO
D
PEP-carboxylase
Detailed Solution
In $C_4$ plants, the primary $CO_2$ fixation occurs in the mesophyll cells.
The enzyme PEP carboxylase (PEPcase) combines $CO_2$ with phosphoenolpyruvate (PEP) to form oxaloacetic acid, a 4-carbon compound.
PEPcase has a high affinity for $CO_2$ and does not react with $O_2$.
RuBisCO acts later, in the bundle sheath cells.
So the first $CO_2$ fixing enzyme in $C_4$ plants is PEP-carboxylase.
The enzyme PEP carboxylase (PEPcase) combines $CO_2$ with phosphoenolpyruvate (PEP) to form oxaloacetic acid, a 4-carbon compound.
PEPcase has a high affinity for $CO_2$ and does not react with $O_2$.
RuBisCO acts later, in the bundle sheath cells.
So the first $CO_2$ fixing enzyme in $C_4$ plants is PEP-carboxylase.