Q21 / 180 · AIIMS 2011 · Botany

Which of the following statements is correct?

  • A
    Photorespiration is useful process.
  • Correct answer
    B
    $\mathrm{C}_4$ plants are more efficient than $\mathrm{C}_3$ plants.
  • C
    $\mathrm{C}_3$ plants are more efficient than $\mathrm{C}_4$ plants.
  • D
    Photorespiration is absent in $\mathrm{C}_3$ plants but present in $\mathrm{C}_4$ plants.

Solution

$C_4$ plants are more efficient than $C_3$ plants because they have little photorespiration while in $C_3$ plants more than half of photosynthetic carbon get lost in photorespiration. $\mathrm{C}_4$ plants are more efficient in picking up $\mathrm{CO}_2$, even in low $\mathrm{CO}_2$ concentration because of high affinity of $\mathrm{CO}_2$ with PEP (phosphoenol pyruvic acid).

Hence, the correct answer is option: 'B'.

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