Question

In leaves of $C_4$ plants, malic acid synthesis during carbon dioxide fixation occurs in:

• A. Epidermal cells
• B. Mesophyll cells
• C. Bundle sheath cells
• D. Guard cells

Answer 1

The correct option is B Mesophyll cells

$C_4$ plants have 2 types of photosynthetic cells - mesophyll and bundle sheath cells. In this type of plant, the initial fixation of CO₂ occur in mesophyll cell. The primary acceptor (phosphoenol pyruvate) combines with CO₂ to form oxaloacetic acid which later reduced to malic acid. Malic acid is then translocated to bundle sheath cell for further decarboxylation.
In leaves of $C_4$ plants, malic acid synthesis during carbon dioxide fixation occurs in mesophyll cells.