CBSE Class 10 Science 2020 · Paper 31/C/1 · Question 20

Part responsible: the xylem (its vessels and tracheids in roots, stems and leaves form one continuous water-conducting channel). Process: the root cells in contact with the soil actively take up ions, so water moves from the soil into the root and is pushed up the root xylem as a column (root pressure). Water evaporating from the leaf cells is lost as vapour through the stomata (transpiration); it is replaced from the xylem of the leaf, and the resulting suction, the transpiration pull, draws water up from the roots. Transpiration pull is the main force during the day, when the stomata are open, and root pressure matters more at night. When the garden was watered, the roots absorbed the water, the xylem carried it to the leaves and stems, and the cells became turgid again, so the plants became fresh.