Which branch of Botany is concerned with the study of photosynthesis?

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.

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 $PEP / OAA$.

Select the incorrect statement $:$

Which of the following is true for photosynthesis?

In plants,the uptake of $CO_2$ and the release of $O_2$ is a process called .........