Aerobic atmosphere is maintained by

Match the following columns:

Column-$I$	Column-$II$
$A$. $PGA$	$P$. Act as oxygenase enzyme
$B$. $OAA$	$Q$. Primary acceptor of $CO_2$
$C$. RuBisCO	$R$. First product of $C_4$ pathway
$D$. RuBP	$S$. First product of $C_3$ pathway

$CO_2$ is constantly released in respiration,yet its level remains fairly uniform because:

Which of the following statements is/are not true?
$I.$ In $CAM$ plants,stomata open during dark and remain closed during the day.
$II.$ Role of $Na^+$ in stomatal opening is now universally accepted.
$III.$ The water potential of root cells is higher than the water potential of soil.
$IV.$ Capillarity theory is the most accepted theory of water movement through plants.
$V.$ The walls of xylem vessels made up of ligno-cellulose have strong affinity for water molecules.

Oxygen is $not$ produced during photosynthesis by

Photosynthesis is a: