i. The soil is the richest source of raw materials for the plant like nitrogen, phosphorous, water and other minerals. Water is essential for all physiological activities of the plant. The absorption of all these substances occurs through a part of the plant called roots.
ii. The plant transport system moves raw materials from roots and energy from leaves. This is done by two independent conducting tubes called xylem which transports water and minerals from the soil and phloem transports the food from leaves to other parts of plants. vessels tracheids of xylem tissue, stem, leaves, and roots form a continuous water conducting channel reaching to all parts of the plant.
iii. The difference of concentration of ions in roots and soil, help water to enter roots from the soil to eliminate this difference (caused by root cells take up ions from soil). This maintains the steady movement of water upwards via roots.
iv. But this pressure is not enough to supply water to heights.
v. Water lost through leaves (or any aerial part of the plant) called transpiration causes a suction which pulls water from xylem cells of roots. Thus, transpiration helps in the absorption and upward movement of water and minerals from soil via roots and reach the top. Also, it helps to regulate the temperature of the plant.