For the process of photosynthesis,all except one of the following items are essential. Point out the exception.

'Sun basket' is

Assertion : Photosynthesis is important due to two reasons.
Reason : Photosynthesis is the primary source of food on earth and responsible for the release of oxygen from green plants.

$A -$ Productivity of $C_3$ plants is higher than $C_4$ plants.
$R -$ Photorespiration occurs in $C_3$ plants.

Choose the correct option:
$(1)$ The first product of the $C_3$ pathway in the Calvin cycle is $PGA / OAA$.
$(2)$ The primary acceptor of $CO_2$ in the $C_4$ pathway is $PEP / OAA$.

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.