NEET BIOLOGY

Detailed explanation-1: -Continuous transpiration occurring in all of the leaves of a plant creates a negative pressure in the water column (xylem). This exerts an upward pull on the water column, called transpiration pull. And thus, the water present in the xylem column transports up to the tip of the stem, leaves, etc.

Detailed explanation-2: -The movement of water through xylem is not active but passive which is caused to transpiration pull. The root pressure is positive whereas the shoot region has negative pressure due to Transpiration. Hence water flows in accordance with its pressure gradient.

Detailed explanation-3: -The xylem distributes water and dissolved minerals upward through the plant, from the roots to the leaves. The phloem carries food downward from the leaves to the roots. Xylem cells constitute the major part of a mature woody stem or root.

Detailed explanation-4: -The outer tissue, called phloem, transports carbohydrates from leaves to the rest of the plant body. The inner tissue, called xylem, transports water and nutrients from the roots to the leaves.

Detailed explanation-5: -Diffusion takes place because there is a water potential gradient between water in the xylem vessel and the leaf (as water is transpiring out of the leaf). This means that water diffuses up the leaf. There is also a pressure change between the top and bottom of the xylem vessels, due to water loss from the leaves.