Given below are two statements. One is labelled Assertion (A) and the other is labelled Reason (R).
Assertion (A): In C₄plants_, photorespiration does not occur.
Reason (R): C₄ plantshave a mechanism that increases the concentration of CO₂ in bundle sheath cells so that the RuBisCO functions as a carboxylase exclusively.
In light of the above statements, choose the correct answer from the options given below.

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Both (A) and (R) are true and (R) is the correct explanation of (A).

Both (A) and (R) are true but (R) is not the correct explanation of (A).

(A) is true but (R) is false.

Both (A) and (R) are false.

answer is A.

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Detailed Solution

In C₄ plants, photorespiration does not occur. C₄ plants have a special anatomy, called Kranz anatomy. Primary carbon fixation and C₃ cycle take place in two different types of cells(spatially separated). This is because they have a mechanism that increases the concentration of CO₂ at the enzyme site. Bundle sheath cells are thick-walled and deep-seated, which does not allow for any kind of gaseous exchange. RuBisCO is located only in bundle sheath cells but is absent in mesophyll cells.

This takes place when the C₄ acid from the mesophyll is broken down in the bundle sheath cells to release CO₂ – this results in increasing the intracellular concentration of CO₂. In turn, this ensures that the RuBisCO functions as a carboxylase, minimizing the oxygenase activity.

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