CBSE Class 11 Biology Revision Notes Chapter 11

CBSE Class 11 Biology Revision Notes Chapter 11 – Transport in Plants

Transportation in plants refers to the transportation of water and nutrients throughout the plant’s body. Plants have a sophisticated mechanism for distributing water and nutrients within their bodies, which students will learn as part of this chapter. Students can refer to the Revision Notes for Chapter 11 by Extramarks if they need concise and easy-to-understand study material for this chapter. The notes are available to download from the Extramarks’ website.

Class 11 Biology Chapter 11 Notes Download

The transfer of substances like minerals, water and solute in plants via xylem and phloem is known as translocation. Chapter 11 introduces students to translocation in-depth and many other important topics which have been discussed below.

Means of Transport

The main ways of transportation in plants:

• The most prevalent form of plant movement is diffusion. It is described as the movement of molecules without energy from a high concentration region to a low concentration zone. Diffusion is a passive process. The concentration gradient, temperature, and pressure all influence diffusion.
• Permease proteins aid in the process of diffusion. It’s also a non-active procedure. When all of the protein that can be transported is used up, transport reaches its maximum. Only particular molecules are allowed to travel via this procedure. Porins and aquaporins are proteins that help in the diffusion process. Porins are pores present in mitochondria and plastids, and certain bacteria. Water molecules are transported through aquaporins, which are water channels.

Facilitated diffusion can be achieved using the following process:

• Symport: Multiple molecules travelling in the same direction

• Antiport: Molecular migration in the opposite direction
• Uniport: Individual molecules move in any direction.

Active Transport in Plants

Molecule transport demands the expenditure of energy. It can move solutes from a low to a high concentration location and vice versa. Membrane proteins enable active transport. It’s a particular type of solute transport.

Plant Water Relations

Plants require water to grow. On the other hand, plants can be harmed by too much or too little water. Transpiration is through which terrestrial plants lose some water as water vapour from their aerial parts.

Water Potential

The potential energy of water is measured by its potential. Solute and pressure potentials influence the cell’s water potential. Pure water has the most water potential. Water always goes from one water potential to the next. The symbol psi or ψ is used to represent water’s potential. Water potential is expressed in Pascals.

The water potential decreases to a negative value when a solute is introduced to pure water. The solute potential is the term for this. The letter ψs stands for it. In the case of pure water, water potential increases when pressure surpasses atmospheric pressure. Water travels from a high-potential zone to a low-potential region or from a dilute solution to a concentrated solution.

Pressure builds up against the cell wall when water enters the plant cell, making it rigid. That raises the possibility of pressure. As a result, the connection between water potential (ψ), solute potential (ψs), and pressure potential (ψp) is as follows:

ψ = ψp+ ψs

Osmosis

This process characterises water molecules travelling through a semipermeable membrane. The concentration gradient and the pressure gradient both impact the flow of water.

Water molecules migrate until the two solutions achieve a state of equilibrium. The pressure used to prevent the net flow of solute molecules across the membrane is known as osmotic pressure. Osmosis is essential for the flow of molecules such as ions, proteins, and polysaccharides across membranes.

Plasmolysis

Plant cell behaviour in response to the external media is constantly changing. The solution is isotonic if the plant cell’s osmotic potential equals external media. If the osmotic potential outside the cell is more massive than inside the cell, the remedy is hypertonic. The answer is hypotonic when the solute potential inside the cell is bigger than the solute potential outside the cell.

Water molecules travel outside the cell in a hypertonic solution. The cell is now known as a flaccid cell. Water travels within a cell when it is submerged in a hypotonic solution. Turgid is how the cell is described. When a plant cell is held in a hypertonic solution, protoplasm shrinks away from the cell wall, known as plasmolysis. As a result of being submerged in a hypertonic solution, water moves out of the cell. Plasmolysis is the term for this.

Imbibition

Imbibition is the process of solids absorbing water and expanding in size. The swelling of raisins in water is the most prominent example of imbibition. Diffusion is water movement from a high concentration to a low concentration or along a concentration gradient.

Long-Distance Transport of Water

The fastest method of water transportation is long-distance water travel. Bulk flow or mass flow is commonly used to transport water, food, and minerals. Between two pressure-differentiated solutions, mass flow occurs.

The transport of chemicals across the vascular tissues of plants is known as translocation. Vascular tissues include the xylem and phloem. Water molecules are transported from the roots to various regions of the plant via the xylem. Food is transported from the leaves to other areas through the phloem.

Different Pathways of Water Absorption

Plants take in water through their roots. Root hairs carry out the absorption of water and nutrients from the soil. Water travels from the base to different sections in two ways. 

• Apoplastic Pathway

Water flows in non-living plant sections such as intercellular gaps and cell walls. The endodermis obstructs this route. Casparian strips protect the endodermis from water flow. It does not involve water moving across the cell membrane.

• Symplast Pathway

Water moves through protoplasts via plasmodesmata, which are cell-to-cell connections. Direct cytoplasm-to-cytoplasm migration is aided by it. This mechanism takes longer than the apoplastic water flow route.

Mycorrhizae are various structures that some plants, such as Pinus, have for water absorption. Mycorrhizae are fungi that form connections with the roots of higher plants. The fungus and the plant roots have a symbiotic interaction. The roots feed sugars and N-containing chemicals to the plant base, while the fungal hyphae help in the mineral ions and water from the soil.

Water Movement up the Plant

• When ions in the soil are actively carried into the vascular tissues of the roots, positive pressure is created inside the base.
• When ions in the soil are actively carried into the vascular tissues of the roots, transpiration pull occurs, resulting in positive pressure inside the base. This pressure is known as root pressure and causes water to rise. Root pressure is determined by cutting a stem horizontally from the core. A liquid will seep from the severed tip. At night, the effect of root pressure may be visible. When the rate of evaporation is poor, excess water in the form of water droplets is noticed towards the tips of the leaves. Guttation is the term used for this.
• Transpiration pull is the force that propels water upward. Dixon and Jolly presented the cohesion-tension hypothesis to explain the upward flow of water in plants. Cohesion is the term used for the attraction between water molecules. Adhesion is the term for the water molecules to other polar molecules. Another feature that boosts transpiration pull is surface tension. Surface tension describes the attraction between water molecules in the liquid phase. During transpiration, water is lost, resulting in negative pressure in the xylem vessels. The phenomenon is known as transpiration pull.

Transpiration

Water vapour is lost from leaves through stomata during transpiration. Stomata are daytime and night-time apertures in the leaves.

Factors Influencing Transpiration

• The rate of transpiration speeds up as the temperature rises.
• A massive surface area accelerates evaporation. It is slowed by excessive humidity and accelerated by wind speed.

Mineral Nutrient Absorption and Transport

Plants take minerals in two ways: passively and aggressively. Because ions are charged and cannot pass the membrane without burning energy, the bulk of transport happens actively. Power is provided through ATP. Sucrose, a photosynthetic end product, is transferred from the source (where synthesis takes place, such as leaves) to the sink (organs that store food). Water movement is unidirectional, but food or sugar transmission is bidirectional.

The pressure-flow theory, also known as the mass flow hypothesis or the Munch hypothesis, was developed for sugar translocation from source to sink. That occurs via the phloem. Phloem consists of sieve tubes, companion cells, and phloem parenchyma. Food is actively transported from the supply to the sink by sieve tubes and companion cells. Sugars are fed into a sieve tube as they travel through the phloem. The hypertonic environment created by the loading in sieve tubes allows water to reach the phloem. The food/sucrose goes towards the sink due to osmotic pressure at the source (with low osmotic pressure). As a result, osmotic pressure appears to be the driving force behind food migration from the supply to the sink.

Class 11 Biology Chapter 11 Notes Download

This chapter clarifies the notion of plant mobility. This chapter is on plant functioning research. Class 11 Biology Chapter 11 notes are available on Extramarks. Students can download them anytime for free.

Importance of Transportation In Plants Class 11 Notes

• The revision notes will help you prepare for your exams more efficiently.
• The chapter notes provide a thorough overview of all the important concepts covered in the chapters.
• As an exam preparation tool, it supplies you with ready-to-use chapter notes.
• These notes are ideal for effective preparation and last-minute revision.

How to Download the Notes of Chapter 11 Biology Class 11

Extramarks provides revision notes for all the chapters included in the curriculum of Class 11 Biology. The Chapter 11 revision notes can be downloaded from the official website of Extramarks.