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Question: PEP is primary \({C}{O}_{2}\) acceptor in (a) \({C}_{4}\) (b) \({C}_{3}\) (c) \({C}_{2}\) (...

PEP is primary CO2{C}{O}_{2} acceptor in
(a) C4{C}_{4}
(b) C3{C}_{3}
(c) C2{C}_{2}
(d) Both C3{C}_{3} and C4{C}_{4} plants

Explanation

Solution

It's one of three known processes for carbon fixation in some plants. In this, a 4-carbon compound which is called oxaloacetic acid (OAA) is the first product by carbon fixation. Plants in tropical desert regions commonly follow this pathway.

Complete answer:
In C4{C}_{4} plants, the initial fixation of CO2{C}{O}_{2} or carboxylation takes place in mesophyll cells. The chloroplasts of mesophylls cells possess enzyme PEP carboxylase for initial fixation of CO2{C}{O}_{2}. The first acceptor of CO2{C}{O}_{2} is phosphoenolpyruvate or PE, which is a 3-carbon molecule. It combines with CO2{C}{O}_{2} within the presence of PEP carboxylase to make oxaloacetic acid or oxaloacetate (OAA) , which is a 4-carbon molecule. Eventually, it's converted into another 4-carbon compound referred to as malic acid.
Later, they're transferred from mesophyll cells to bundle sheath cells. Here, OAA is weakened to yield CO2{C}{O}_{2} and a 3-C molecule. The CO2{C}{O}_{2} thus formed is employed within the Calvin cycle, whereas 3-carbon molecule is transferred back to mesophyll cells for regeneration of PEP
-The majority of plants produce 3-carbon acid called 3-phosphoglyceric acid (PGA) as a primary product during CO2{C}{O}_{2} fixation. Such a pathway is understood because the C3{C}_{3} pathway which is additionally called the Calvin cycle. -Photorespiration is known as C2{C}_{2} cycle. Occurs in photosynthetic organisms. It is light-dependent, where O2{ O }_{ 2 } is taken, and CO2{C}{O}_{2} is released. In this metabolic pathway, sugars are oxidized to CO2{C}{O}_{2} in the light.
So, the correct answer is ‘C4{C}_{4}‘.

Note: Corn, sugarcane, and a few shrubs are samples of plants that follow the C4{C}_{4} pathway. The Calvin pathway may be a common pathway in both C3{C}_{3} plants and C4{C}_{4} plants. But this takes place only within the mesophyll cells of the C3{C}_{3} plants and not within the C4{C}_{4} plants.