Question

Fill in the correct sets in the given pathway at A, B and C. In which of the following options correct words for all the three blanks A, B and C are indicated?

• A. A - Decarboxylation, B - Reduction, C - Regeneration
• B. A - Fixation, B - Transamination, C - Regeneration
• C. A - Carboxylation, B - Decarboxylation, C - Reduction
• D. A - Fixation, B - Decarboxylation, C - Regeneration

Answer 1

The correct option is D A - Fixation, B - Decarboxylation, C - Regeneration

The given picture denotes $C_4$ cycle, which is also known as Hatch and Slack pathway. In the given pathway:
A denotes 'fixation'.
B denotes 'decarboxylation'.
C denotes 'regeneration'.
The $C{O}_2$ acceptor in $C_4$ plants in phosphoenolpyruvate (PEP). PEP reacts with $C{O}_2$ to form oxaloacetic acid, which is reduced by NADPH to form malic acid. The malic acid then reacts with RUBP to form pyruvic acid and PGA. The pyruvic acid is then phosphorylated by ATP to regenerate PEP while PGA is converted to triose phosphate as far as $C_3$ plants. These reactions are called as the Hatch and Slack pathway.