Photosynthesis in Higher Plants — BIOLOGY STD 11 Science — Question

1. C₄ plants.

Explanation:

Mechanism of C₄ pathway (or Dicarboxylic acid pathway or Hatch and Slack pathway) can be illustrated as follows:

Initial fixation in C₄ plants, initial fixation of CO₂ or carboxylation occurs in mesophyll cells. The chloroplasts of mesophyll cells possess enzyme PEP carboxylase (or PEP case) for initial fixation of CO₂ The primary acceptor of CO₂ is phosphoenol pyruvate or PEP It combines with CO₂ in the presence of PEP carboxylase (or PEPcase) to form oxaloacetic acid or oxaloacetate (OAA).

$\text{PEP}+\text{CO}_{2}+\text{H}_{2}\text{O}\ {\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ }}\text{OAA}+\text{H}^{3}\text{PO}_{4}$

$\text{Pyruvate}+\text{ATP}+\text{H}_{3}\text{PO}_{4}\ {\xrightarrow{\ \ \ \ \ \ \ \ \ \ \ }}\text{PEP}+\text{AMP}+\text{PPi}$