NEET BIOLOGY

Detailed explanation-1: –Positive root pressure: Positive root pressure can be defined as the pressure required to push the water absorbed by the root hairs up to small heights in the stem through water-conducting vessels known as xylem.

Detailed explanation-2: -root pressure, in plants, force that helps to drive fluids upward into the water-conducting vessels (xylem). It is primarily generated by osmotic pressure in the cells of the roots and can be demonstrated by exudation of fluid when the stem is cut off just aboveground.

Detailed explanation-3: -Root pressure provides a force, which pushes water up the stem, but it is not enough to account for the movement of water to leaves at the top of the tallest trees. The maximum root pressure measured in some plants can raise water only to 6.87 meters, and the tallest trees are over 100 meters tall.

Detailed explanation-4: -The effect of root pressure in the transport of water is more important at night as: The stomata remain closed during the night time. In all higher plants, the movement of water chiefly occurs due to root pressure and transpiration pull.

Detailed explanation-5: -<br> Reason:-Root pressure is responsible for pulling up water to small heights in the stem.