Transportation in Plants: Water Absorption in Plants, Active Absorption

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Water Absorption in Plants

The osmotic process involves diffusion pressure deficit (DPD) of the cells.
The root hairs have more DPD as compared to soil solution.
There is an involvement of both Osmotic and non-osmotic mechanisms.
Symplastic movement of water in root hairs.
- The water first enters the cell sap and then passes from one cell to another.
Root pressure, bleeding, and guttation, etc. are the evidences for active absorption.

It occurs due to the activity of the upper part of the plant such as shoot system.
The absorption is due to transpiration in the upper part.
Tension is created in the Xylem sap by transpiration pull.
Water moves through the free spaces or apoplast of root.
- The water can reach up to endodermis through apoplast.
Even if all the roots are removed, the absorption of water is continued.

This driving force is behind uptake and transport of water.
The process of water evaporation through openings called stomata.
Due to the cohesive forces, the pull in the xylem tissues extends all the way down.
The negative water pressure eventually results in an increase of water uptake from the soil.

There is an increase in the curvature of the meniscus as more molecules evaporate from the water film.
To reduce the tension, water from the surrounding cell is pulled towards this area.

It is due to the water potential gradient; water moves from the roots to the leaves.
The water potential gradient is the highest in the water surrounding the roots.
The water potential gradient is the lowest in the airspace within the spongy parenchyma.

By hydrogen bonds the water molecules stick to each other.
Within the xylem through the hydrogen bonds, the hydrogen bonding forces are communicated to water forces.

Q 1. List out the different means of transportation in plants.

Answer:

The different means of transportation in plants are:

i) Simple diffusion

ii) Facilitated diffusion

iii) Osmosis

iv) Active transport

Q 2. How is the water and food transportation occur in plants?

Answer: Water transportation occurs through Xylem and Food transportation occurs through Phloem.

Q 3. What are the various driving forces responsible for transportation in plants?

Answer:

The various driving forces responsible for transportation in plants are:

i) Transpiration

ii) Force of surface tension

iii) Water potential gradient

iv) The force of hydrogen bonding between water molecules