Which crop provides the highest net primary productivity of $2-4 \ kg/m^2$ from solar energy?

In sugarcane,when $14CO_2$ is fixed into malic acid,which enzyme is responsible for the fixation of $CO_2$?

In $C_4$ plants,the primary acceptor of $CO_2$ is ......

The following figure represents the Hatch and Slack pathway. Identify $P, Q, R$ and $S$.

$RuBisCo$ is an enzyme that acts both as a carboxylase and oxygenase. Why do you think $RuBisCo$ carries out more carboxylation in $C_{4}$ plants?

Describe the $C_4$ pathway.