(i) The blocking results in the stoppage of translocation of organic solutes. 
(ii) The phloem sap contains three major classes of organic compounds-organic acids, amino acids and sucrose besides some cations, anions and hormones. Sucrose is the major metabolite, which is supplied from leaves to other parts of the plant. Of total solute content in the phloem, sucrose content ranges from 50-85%.

The water molecules attract each other by mutual force .this force is called cohesive force. The attraction between the walls of xylem elements and other water molecules is known as adhesion. Root hair absorb water from the soil, movement of water from soil to root hair results from the pressure exerted by cortical cells of the root into the xylem vessels, resulting to raise the water column in ascending parts of the plant and is called root pressure. As a result of transpiration water is drawn in the intercellular spaces from mesophyll cells which consequently draw water osmotically from the nearby cells and thus a diffusion pressure deficit is developed. Due to this the adjacent cells take water from xylem of vein of leaf. This xylem is connected with the xylem of root through stem xylem. A tension is setup in the water column of the xylem and the whole column is physically pulled up.

Role of potassium ions in transpiration: Levitt explained the mechanism of stomata action. In light starch produced during photosynthesis is converted into organic acids which cause a low concentration of potassium ions. When the concentration of organic acid is increased in guard cells, this increases the concentration of cell sap followed by subsequent absorption of water. In dark photosynthesis stops, accompanied by an increased concentration of CO2, the organic acids are converted into starch. The water comes out of guard cells it reduces the truer pressure and stomata get s closed.

Desert plants have a different mechanism of photosynthesis and it is called C₄ pathways. The evolution of the C₄ photosynthetic system is probably one of the strategies for maximising the availability of CO₂ while minimising water loss. C₄ plants are twice as efficient as C₃ plants in terms of fixing carbon (making sugar). However, a C₄ plant loses only half as much water as a C₃ plant for the same amount of CO₂ fixed.

The leaf of the plants are heated by the temperature of the environment and also by the heat released during photosynthesis. Thus, transpiration provides a cooling mechanism for the plant to release excess heat in the leaves in order to maintain internal temperature necessary for biological and chemical processes. Transpiration tends to occur more quickly at higher temperature, i.e in suny ays due to increased evaporation. And on windy days the moisture present in the air is swept away from the leaf causing it to transpire more. Whereas on cool and calm days, the humidity rate can rise which in turn cause a decrease in transpiration.