Name: Transport Mechanism in Plants
Uploaded: 2019-07-19
Duration: 5 min
Description: Plants contain a vast network of conduits which consist of the xylem and phloem. This is more like the circulatory system. Learn more.

Question

Describe mechanism for absorption of water.

Accepted Answer

Soil is the reservoir of water and minerals for the plant. Water is absorbed either by passive or active absorption methods. Minerals are absorbed by plants in the ionic (dissolved) form, mainly through roots and then transported.

Passive Absorption:

Mainly water is absorbed through the roots (and not by the roots) by passive process

The driving force of passive absorption is transpiration pull.

There is creation of diffusion pressure deficit (DPD) which allows water molecules to enter the root hair.

Passive absorption occurs during day when transpiration is also active. It stops at night when transpiration stops.

Rapid transpiration creates a tension in the xylem vessel due to negative water potential.

This tension is transmitted to xylem in the roots. As a result, the water is pulled upwards passively.

Active Absorption:

Water is absorbed due to the metabolic and other activities of roots.

The driving force is the root pressure developed, in the living cells of root.

This happens generally against the DPD, and thus, ATP is needed for the absorption.

ATP is generated by the respiratory processes inside the root cells.

The root pressure is a hydrostatic pressure generated due to osmosis which forms a gradient of DPD develops from cell of epiblema to the pericycle of roots.

If there is no osmosis, then absorption takes place by direct consumption of ATP.

Describe mechanism for absorption of water.

Important Questions on Plant Water Relation

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