The C4 carbon cycle is a CO2 concentrating mechanism evolved to reduce photorespiration. The following are stated as important feature of the C4 pathway:The leaves of the C4 plant have Kranz anatomy that distinguishes mesophyll and bundle sheath cells.In the peripheral mesophyll cell, atmospheric CO2 is fixed by phosphoenol pyruvate carboxylase yielding a four carbon acidIn the inner layer of mesophyll, NAD malic enzyme decarboxylates four carbon acids and releases CO2.CO2 is again re-fixed through Calvin cycle in the bundle sheath cells.Which one of the following combinations is correct?

C 4 PHOTOSYNTHESIS

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

A	2, 3 and 4
B	1, 2 and 3
C	1, 2 and 4
D	1, 3 and 4

Explanation:

Detailed explanation-1: -C4 Pathway (Hatch and Slack Pathway) Such plants are special and have certain adaptations as well. The C4 pathway initiates with a molecule called phosphoenolpyruvate (PEP) which is a 3-carbon molecule. This is the primary CO2 acceptor and the carboxylation takes place with the help of an enzyme called PEP carboxylase.

Detailed explanation-2: -C4 plants-including maize, sugarcane, and sorghum-avoid photorespiration by using another enzyme called PEP during the first step of carbon fixation. This step takes place in the mesophyll cells that are located close to the stomata where carbon dioxide and oxygen enter the plant.

Detailed explanation-3: -The C4 pathway acts as a mechanism to build up high concentrations of carbon dioxide in the chloroplasts of the bundle sheath cells. The resulting higher level of internal carbon dioxide in these chloroplasts serves to increase the ratio of carboxylation to oxygenation, thus minimizing photorespiration.

Detailed explanation-4: -Note: C4 plants avoid photorespiration because they have the enzyme called PEP during the first step of carbon fixation. Hence the carbon dioxide regenerated during photorespiration is recycled through PEP.

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