What are the two circuits for the installation of $CO_2$?

Who proposed the theory of photosynthesis in guard cells?

Consider the following statements.
$I.$ The portion of the spectrum between $300-500 \;nm$ is also referred to as Photosynthetically Active Radiation $(PAR)$.
$II.$ Magnesium,calcium and chloride ions play prominent roles in the photolysis of water.
$III.$ In cyclic photophosphorylation,oxygen is not released (as there is no photolysis of water) and $NADPH$ is also not produced.

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.

Photosynthesis without the evolution of oxygen is a characteristic of which of the following?

Select the correct option regarding photosynthesis.