Question

The enzyme RuBisCO has

• A. more affinity for $C{O}_2$ than for $O_2$
• B. more affinity for $O_2$ than for $CO$
• C. equal affinity for both
• D. more affinity for sugars than for $C{O}_2$

Answer 1

The correct option is A more affinity for $C{O}_2$ than for $O_2$

RuBisCO enzyme is invlolved in $C{O}_2$ fixation. It has a much greater affinity for $C{O}_2$ when the $C{O}_2$:$O_2$ is nearly equal. It is the relative concentration of $O_2$ and $C{O}_2$ that determines which of the two will bind to the enzyme. When $O_2$ binds to RuBisCO, it results in decrease in $C{O}_2$ fixation which is called photorespiration.