According to the CBSE Syllabus 2023-24, this chapter has been removed from NCERT Class 11 Biology textbook.
Transportation is the process of the movement of water and minerals to all parts of the plant body. Plants have a specialized system that enables them to distribute water and nutrients throughout their body. They use several processes, such as translocation, absorption, storage and utilization of water.
Let us have a look at the different processes of transport in plants.
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Transport Mechanisms
Transport in plants takes place through different mechanisms:
Simple Diffusion
In this system, the molecules move from a region of higher concentration to a region of lower concentration. This process requires no energy.
Facilitated Transport
Here, the system moves molecules from a region of higher concentration to a region of lower concentration with the help of a carrier, usually a protein. This process does not require any energy and hence is known as the passive process.
Active Transport
This mechanism transfers molecules from a region of lower to a region of higher concentration with the help of membrane proteins. This system is termed active transport because it requires ATP to function.
For more information on Transportation in Plants and Apoplast Movement in Plants, watch the below videos
Water Potential
Water potential is used by plants to transport water to the leaves, that help in carrying out photosynthesis. Solute potential and pressure potential are the two main components of water potential.
The solute potential is also known as osmotic potential and is negative in the plant cell. Pressure potential is positive in the plant cell. The higher the concentration of water in the system, the greater will be the water potential.
Osmosis
Osmosis is the movement of molecules from a region of higher concentration to a region of lower concentration across a semi-permeable membrane until an equilibrium is reached.
The plant cell wall is freely permeable to substances in solution and water. Osmosis is of two types:
- Endosmosis: This is the movement of water molecules enters into the cell when the cell is placed in a hypotonic solution.
- Exosmosis: This is the movement of water molecules out of the cell when the cell is placed in a hypertonic solution.
Plasmolysis
Plasmolysis is the process in which a plant cell loses water when placed in a hypertonic solution. It depends upon three types of solutions:
- Isotonic: This refers to two solutions with the same osmotic pressure across the semi-permeable membrane.
- Hypotonic: This is the solution which has a lower osmotic pressure than another solution.
- Hypertonic: This is the solution with higher osmotic pressure than another solution.
The cells, when placed in a hypotonic solution, swell or get deplasmolysed. Whereas the cells, when placed in a hypertonic solution, shrink or get plasmolysed.
Imbibition
Imbibition is the process of adsorption of water by solids called colloids. This results in an increase in the volume. For example, the adsorption of water by seeds.
Transpiration
Transpiration is the removal of excess water from the aerial parts of the plants. It mainly occurs through the stomata of the leaves. It is influenced by light, temperature, wind and humidity.
The xylem helps in the movement of water from the roots to the leaf veins. The phloem helps in the movement of food prepared by the leaves to various parts of the plants.
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Transport in Plants Class 11 – Important Questions
- Name the factors that affect the rate of diffusion.
- Define porins.
- What is the difference between osmosis and diffusion?
- What is root pressure, and how does it help in the movement of water in the plant?
- Why do guards cells that are found in the stomata open and close during transpiration?
- Define water potential.
Further Reading:
Active and Passive Transport – Its Difference
Important Questions on Transport in Plants
Frequently Asked Questions on CBSE Class 11 Biology Notes Chapter 11 Transport in Plants
What is plasmolysis?
When a cell is placed in a hypertonic medium, it tends to lose its water content. This process is said to be the plasmolysis of the cell.
What are the xylem and phloem?
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.
What is the difference between hypertonic and hypotonic?
A solution will be hypertonic to a cell if its solute concentration is higher than that inside the cell and the solutes cannot cross the membrane. If a cell is placed in a hypotonic solution, there will be a net flow of water into the cell, and the cell will gain volume.
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