Green plants are grown in an aquarium for the purpose of:

Select the correct option:
$(1)$ Julius von Sachs / $T$. $W$. Engelmann proved with evidence that glucose is produced when plants grow.
$(2)$ In $PS-II$,maximum light absorption occurs at a wavelength of $680 \, nm / 800 \, nm$.

How many molecules of water are needed by a green plant to produce one molecule of hexose or to reduce $6$ molecules of $CO_2$?

Maximum photosynthesis occurs by ..........

Assertion : Cyclic pathway of photosynthesis first appeared in some eubacterial species.
Reason : Oxygen started accumulating in the atmosphere after the non-cyclic pathway of photosynthesis evolved.

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.