Question

Which of the following equation holds true for acidification reactions of CAM pathway?

• A. PEP + $C{O}_2+H_{2}O\stackrel{PEPcase}{\to }OAA+H_{3}P{O}_4$
• B. OAA + NADH$\stackrel{Dehydrogenase}{\to }Malcacid+NA{D}^{+}$
• C. Malic acid +$NAD{P}^{+}\underset{enzyme}{\overset{Malic}{\to }}Puruvicacid+CO+NADPH$
• D. Both (a) and (b)

Answer 1

The correct option is D Both (a) and (b)

Crassulacean plants have developed a unique mechanism to perform photosynthesis without much loss of water, They perform acidification or dark fixation of $C{O}_2$ during night and denitrification during the day. During the night, when stomata are open, $C{O}_2$ combines with phosphoenol pyruvic acid (PEP) to form oxaloacetic acid (OAA) in the presence of enzyme PEP carboxylase. OAA is subsequently converted to malic acid in the presence.OAA is subsequently converted to malic acid in the presence of enzyme malic dehydrogenase. Malic acid produced in dark as a result of acidification is stored in the vacuoles. During the day, when stomata are closed, the Malic acid is decarboxylated to produce pyruvic acid and evolve $C{O}_2$ (deacidification).

So, the correct answer is 'Both (a) and (b)'.