CBSE Class 10 Science 2019 · Paper 31/5/1 · Question 12

(a) The two water-conducting tissues are xylem vessels and xylem tracheids. Water enters the root xylem continuously because the root cells in contact with the soil actively take up ions. This creates a difference in the concentration of ions between the root and the soil, so water moves from the soil into the root to remove the difference. As the uptake of ions goes on, there is a steady movement of water into the root xylem, which pushes the column of water upwards. (b) Plants do not move, and plant bodies have a large proportion of dead cells in many tissues, which need no energy. So plants have low energy needs compared with animals, and a relatively slow transport system is enough for them.