(N/A) The experimental setup shown is a classic demonstration of the transpiration pull theory.
$1$. The setup consists of a leafy shoot attached to a glass tube filled with air-free water,with the lower end immersed in a beaker containing mercury.
$2$. As transpiration occurs from the leaves of the shoot,water is lost in the form of water vapor.
$3$. This loss of water creates a negative pressure or tension (transpiration pull) in the xylem vessels of the shoot.
$4$. This tension is transmitted down to the water column in the tube,which in turn pulls the mercury up into the tube.
$5$. Therefore,this experiment demonstrates that transpiration generates a significant pulling force (transpiration pull) capable of lifting a water column against gravity,which is the primary mechanism for water transport in plants.