NCERT Solutions Class 11 Biology Chapter 11

NCERT Solutions for Class 11 Biology Chapter 11

Students will find detailed and accurate answers to the questions listed at the end of NCERT Class 11 Biology Chapter 11 in NCERT Solutions for Class 11 Biology Chapter 11. This Chapter covers the different mechanisms of how nutrients are transported from one plant cell to another. Students can refer to the NCERT Solutions by Extramarks to understand the chapter better, get accurate answers to practise questions, and perform better in exams.

NCERT Solutions for Class 11 Biology Chapter 11 – Transport in Plants

The transport process that takes place in plants is covered in-depth in Chapter 11 Biology. The chapter talks about how different nutrients make their way from one cell to another in plants. It covers many different topics such as active transportation, diffusion, facilitated diffusion, the relationship between plants and water, movement of water across different parts of a plant, osmosis, imbibition of plants, and plasmolysis. Photosynthesis and Transpiration will also be explained in the chapter.

NCERT Solutions for Class 11 Biology Chapter 11 can be found below:

Study Important Questions for Class 11 Biology Chapter 11 Transport in Plants

Access the important questions and their answers from NCERT Solutions for Class 11 Biology Chapter 11 – Transport in Plants.


NCERT Solutions for Class 11 Biology Chapter 11 – Transport in Plants

Introduction to Transport in Plants

Transport of water in plants along with multiple processes like transpiration, diffusion, etc. are discussed in the Biology Chapter 11. Plants absorb food and water with their roots and like animals, they cannot search for these things. The water absorbed by them is transported to their multiple different parts with the help of their stem and roots. Plants prepare their food in the leaves which is then transported through the phloem. The entire process of water and food transportation in plants can be understood with the help of this chapter which is why studying it in detail is a must. The primary mediums for water transportation are transpiration and photosynthesis. 

NCERT Solutions Class 11 Biology Chapter 11 by Extramarks comprise answers to all the NCERT textbook questions listed at the end of the chapter. The solutions are prepared by subject-matter experts at Extramarks who have ensured that every answer is accurate and explained in the simplest possible language.

Class 11 Transport in Plants NCERT Solutions Free Download

All the practise exercise questions have been answered accurately and in detail in the NCERT Solutions for Class 11 Biology Chapter 11 by Extramarks. The solutions aid in making the learning process easy for students. Also, referring to these NCERT Solutions will help students get a sense of how they should answer the questions in their final exams.

Students can refer to Class 11 Biology Chapter 11 NCERT Solutions after solving the questions in the NCERT textbook on their own to see how well they are prepared and identify their weak areas.

Class 11 Biology Chapter 11 Transport in Plants NCERT Solutions

Plants have tissues that assist in the transportation of minerals, water, and nutrients. Transporting minerals and nutrients is possible because of the existence of Phloem and Xylem tissues. Xylem is made of dead cells. It is an elongated tube-like structure that aids in mineral and water transportation. Phloem on the other hand is made up of living cells and transports or translocates water and sucrose along with other sugars, amino acids, and hormones. 

Questions about how substances move from one cell to another and whether moving substances require metabolic energy or not are discussed in this chapter. If you have ever wondered how a tall tree manages to receive water to the tip of it is also explained here. The process of transpiration and root pressure play an important role in executing transportation of water to the leaves. Plants do not have a circulatory system set up and require substances to move over longer distances as compared to other creatures. Water absorbed by the roots is required to reach every part of the tree (including the tip of the stem which is developing).

Food made by the leaves is required in all parts of the plant as well, including its roots. Plants are supported physically by transport mechanisms present in the vascular bundles. Phloem is found in the lower levels. The strong xylem vessels present in the root’s centre support the plant and give it strength against any force that can pull it out of the ground. To provide support to the plant against bending (caused due to plant weight and wind), xylem and phloem are present on the edges of the stems.

Marks Distribution for Transport in Plants Class 11 NCERT

The fourth Unit of Biology Class 11 includes the Transport in Plants chapter in it. The unit has a weightage of 18 marks. Both short and long questions can be asked from this chapter. Short questions that carry 1 mark and long questions that carry 5 marks can be asked in the exams.

Role of Root Pressure During the Movement of Water in Plants

The movement of water  in plants is significantly affected by root pressure. Root pressure – in the form of positive pressure that develops in the plant roots – carries out the absorption of nutrients from the soil. Positive pressure contributes towards restoring the continuous chain of water molecules that are present in the xylem by giving a slight push to water. Transpiration pull causes the xylem to wither due to the tensions that are created by it. Transpiration pull is what maintains the flow of water from the roots to the shoots. 

Why Should You Refer to NCERT Solutions Class 11 Biology Chapter 11 Transport in Plants by Extramarks?

With Class 11 Biology Chapter 11 NCERT Solutions, students get familiar with all the questions that they might face in the exams. Explanations are given with appropriate diagrams. The right approach to writing answers can be learned by students by referring to these solutions. This approach can then be incorporated into their answers for better marks. 

These NCERT Solutions are the best study material one can refer to. NCERT Solutions for Class 11 Biology Chapter 11 cover every question in Chapter 11 – Transport in Plants. 

Solved Examples

  1. What is the symbol used to denote water potential?
  1. The Greek letter, Psi
  2. Lambda
  3. Alpha
  4. Pascal

Answer: (A) The Greek letter, Psi

  1. Which of the following is not a factor that affects the rate of Diffusion?
  1. Gradient of concentration
  2. Membrane permeability
  3. Temperature and pressure
  4. Active Transport

Answer: (D) Active Transport

Related Questions

  1. What are the different types of osmosis?
  2. Endosmosis
  3. Exosmosis
  4. Both (A) and (B)
  5. None of the above

Ans. The answer is C, both (A) and (B)

  1. Which of the following tissues transport food materials in plants?
  2. Phloem
  3. Xylem
  4. Parenchyma
  5. Collenchyma

Ans. The answer is A, Phloem.

Q.1 What are the factors affecting the rate of diffusion?


Diffusion is a process of passive movement (ATP/energy is not required) of solutes from one place (higher concentration) to another (lower concentration) until the solute concentration on both the places is equal. Several factors that affect the rate of diffusion are:

  1. Concentration gradient: Diffusion rate depends upon the concentration of solute at the two points. Larger the concentration difference between the two points, higher is the rate of diffusion.
  2. Permeability of the membrane: More permeable the membrane that is separating the solutes, faster is the process of diffusion.
  3. Temperature: Increase in temperature increases the rate of diffusion.
  4. Distance: Diffusion rate is inversely proportional to the distance solute has to travel.
  5. Size of the molecules: Smaller molecules diffuse faster.

Q.2 What are porins? What role do they play in diffusion?


Porins are the proteins that form huge pores in the outer membranes of bacteria, mitochondria and chloroplast. They act as pores by forming channels in the membrane through which a variety of molecules can diffuse. They are large enough to allow passive diffusion of solutes across the membrane. There are different types of porins for transportation of different types of molecules.

Q.3 Describe the role played by protein pumps during active transport in plants.


Active transport requires energy to facilitate the transport of molecules against their concentration gradient. It is needed where molecules cannot cross the plasma membrane by simple diffusion or when transport of molecules against their concentration gradient is required. There are specific protein pumps (protein channels) that facilitate the transport of such molecules by using the energy from ATP. Hydrolysis of ATP induces a conformational change in protein pumps that allows movement of molecules through it. When all the protein transporters are in use, the transport reaches its peak level or attains a saturation level. This is a highly selective process.

Q.4 Explain why pure water has the maximum water potential.


Water potential refers to the tendency of water molecules to flow from one place to another as a result of gravity, osmosis, or capillary action. It mainly deals with the free energy (kinetic energy in a liquid and gaseous state) of water molecules. Presence of any other molecule in water decreases the kinetic energy of its molecules. In the absence of any other molecules, kinetic energy (free energy) of water molecules will be highest and so will the water potential. Thus, pure water has maximum water potential since it has maximum kinetic energy.

Q.5 Differentiate between the following:

(a) Diffusion and Osmosis

(b) Transpiration and Evaporation

(c) Osmotic Pressure and Osmotic Potential

(d) Imbibition and Diffusion

(e) Apoplast and Symplast pathways of movement of water in plants.

(f) Guttation and Transpiration.


(a) Diffusion and Osmosis

Diffusion Osmosis
Diffusion is the passive movement of molecules along a concentration gradient. Osmosis is the diffusion of solvent (water) across a semi-permeable membrane.
It can occur in a liquid or gaseous state. It occurs in liquid medium only.
It does not require the presence of water. Presence of water is a must.
It does not require a semi-permeable membrane. It requires a semi-permeable membrane.

(b) Transpiration and Evaporation

Transpiration Evaporation
It is the loss of water from plants through stomata found on the bottom surface of the leaves. It is the loss of water from any surface (living or non-living).
It is a physiological process. It is a physical process.
It is influenced by many physiological and environmental factors. It is driven by only environmental factors.

(c) Osmotic Pressure and Osmotic Potential

Osmotic Pressure Osmotic Potential
Osmotic pressure is the pressure which needs to be applied to a solution to prevent the inward flow of water across a semi-permeable membrane. Osmotic potential is the numerical value of osmotic pressure with an opposite sign.
It is a positive pressure and its value increases with increase in the concentration of solute particles. It is negative pressure and its value decreases with increase in the concentration of solute.

(d) Imbibition and Diffusion

Imbibition Diffusion
Imbibition is the absorption of water by solids or colloids by simple diffusion. Diffusion is passive movement of molecules, ions or particles from one area to another along their concentration gradient.
It involves the movement of liquid. It involves the movement of liquid, gas and solid particles.

(e) Apoplast and Symplast pathways of movement of water in plants

Apoplast pathways Symplast pathways
Apoplast pathway of movement involves the transport of water through the space found between two adjacent cell walls of epidermis and cortex. It involves the transport of water through protoplast.
It is a faster process and water moves by mass flow. It is a relatively slow process.

(f) Guttation and Transpiration

Guttation Transpiration
It is the loss of water from leaves of plants in the form of water droplets. It is the loss of water from leaves in the form of vapours.
It usually occurs at night or early mornings. It occurs during the day.
It is an uncontrolled process and occurs at the endings of leaf veins. It is a controlled process and occurs through stomata.

Q.6 Briefly describe water potential. What are the factors affecting it?


Water potential measures the tendency of water to move from one area to another. Water potential is expressed in potential energy per unit volume and is represented by the Greek letter Ψ. Pure water has maximum water potential and mixing of any solute in it decreases its water potential. The greater the concentration of water in a system, the higher is its kinetic energy or water potential. Water potential of pure water at standard temperature and pressure is zero. Solute potential (the magnitude of lowering of water potential due to dissolution of a solute in water) and pressure potential (the magnitude of increase in water potential due to the application of pressure greater than atmospheric pressure) are the two important components that determine the water potential.

Factors affecting water potential are:

Water potential is affected by solute concentration and pressure.

1. Increase in solute concentration decreases water potential and is known as solute potential.

2. Application of pressure (greater than atmospheric pressure) increases water potential and is known as pressure potential.

Q.7 What happens when a pressure greater than the atmospheric pressure is applied to pure water or a solution?


When the pressure greater than atmospheric pressure is applied to pure water or a solution, its water potential increases. It helps in the transport of water in biological systems like in plants. When water enters the cell, it builds pressure against the cell wall and subsequently, the cell wall exerts an equal pressure in the opposite direction to maintain its rigidity.

Q.8 (a) With the help of well-labeled diagrams, describe the process of plasmolysis in plants, giving appropriate examples.

(b) Explain what will happen to a plant cell if it is kept in a solution having higher water potential.


(a) Plasmolysis is the loss of water from cells when they are surrounded by a hypertonic (or more concentrated) solution. During plasmolysis, water moves out of the cell, first from the cytoplasm and then vacuoles. This results in detachment of the cell membrane of the plant cell from the cell wall. In plasmolysis, cytoplasm shrinks and gets detached from the cell wall. The cell is said to be plasmolysed. It is a reversible phenomenon. Thus, during plasmolysis, water movement occurs across the membrane from an area of high water potential to an area of lower water potential, that is, from the cell into its surrounding medium. The shrinkage of the onion peel when placed in the concentrated salt solution is an example of plasmolysis.

(b) Water potential is the tendency of water to move from one place to another. Water flows from the area of high water potential to the area of low water potential. When a plant cell is placed in a solution of high water potential cell, water moves into the plant cell and builds pressure against the wall called turgor pressure. However, the plant cell does not burst because of the presence of the cell wall.

Q.9 How is the mycorrhizal association helpful in absorption of water and minerals in plants?


The mycorrhizal association is a symbiotic relationship between plant roots and fungi. Fungal filaments either form a dense network around the plant roots or penetrate them and provide a large surface area (which roots alone cannot provide) for the absorption of water and minerals from the soil surrounding it. This strategy helps in providing adequate amounts of mineral ions and water to the plant.

Q.10 What role does root pressure play in water movement in plants?


When minerals enter the roots of the plant, they decrease the water potential inside the root causing water to move in (water moves from an area of high water potential to the area of low water potential). This increases the pressure inside the xylem. This pressure is a positive pressure and called root pressure.

  • It helps in pushing water into the roots up to small heights.
  • It also helps in pushing out excess water in the form of droplets from the tip of grass blades or leaves during the night or early morning.

Q.11 Describe transpiration pull model of water transport in plants. What are the factors influencing transpiration? How is it useful to plants?


Transpiration is the process of loss of water by mesophyll cells of leaves through stomata. During the day time, stomata are open, so water is lost quickly as it reaches from roots to leaves. This results in the creation of a negative hydrostatic pressure in the mesophyll cells that causes mesophyll cells to draw water from nearby veins of leaves. The negative pressure is gradually transmitted downwards from leaves to roots via xylem tissues. This causes continuous upward movement of the water column. Transport of water in plants is explained by transpiration pull theory. This theory has two essential features:

(i) Cohesion between water molecules and adhesion between water and xylem tissues, and

(ii) Transpiration pull

Factors affecting transpiration are:

(i) Physiological factors like the number and distribution of stomata, and

(ii) Environmental factors like the intensity of light, air, humidity and temperature.

The usefulness of transpiration to plants:

  • Transpiration is helpful to plants as it creates a negative pressure in the xylem that causes continuous upward movement of water.
  • It helps in the absorption of water and minerals from the soil.
  • Water reaching from roots to leaves is used for photosynthesis.
  • Water also provides a cooling effect.
  • It helps in maintaining the turgidity of plant cells.

Q.12 Discuss the factors responsible for ascent of xylem sap in plants.


The factors responsible for ascent of sap (transport of water and minerals) are:

  1. Transpiration pull: It creates a negative pressure in the xylem that causes continuous upward movement of sap.
  2. Cohesion (between water molecules) forces and adhesion (between water molecules and xylem tissues) forces along with transpiration pull create a water column within xylem that helps in the continuous upward movement of sap.

Q.13 What essential role does the root endodermis play during mineral absorption in plants?


The endodermal cells of the root have proteins embedded in their plasma membrane that actively pump ions from the epidermis into the cytoplasm of the endodermal cells. They let some solutes cross the membrane but not others, thus acting as control points. This helps the plant in controlling the quantity and type of solutes that reach the xylem. Root endodermis allows transportation of ions in one direction only due to the presence of a waxy layer made of the suberin (Casparian Strip). It uptakes the selected mineral ions by active transportation. Minerals present in the soil enter the root epidermis first, either by passive or active transport.

Q.14 Explain why xylem transport is unidirectional and phloem transport bi-directional.


Xylem transports water from roots to leaves. Transpiration of water through leaves generates a pull that causes continuous upward movement of water. Thus, transport in the xylem is unidirectional.

Phloem, on the other hand, is the transport vessel for food. Food synthesized by leaves during photosynthesis is transported from leaves to other parts of the plant by phloem (for utilization and storage). During spring, food is transported from storage places to the developing bud. Thus, transport in phloem is bi-directional.

Q.15 Explain pressure flow hypothesis of translocation of sugars in plants.


Plants synthesize glucose via photosynthesis that is converted into sucrose for transport through the phloem. Phloem consists of companion cells and sieve tube cells. Pressure flow hypothesis best explains the flow of food in the phloem.

1. Sucrose is transported into a companion cell, then into sieve tube by active transport.
2. Loading of sucrose in phloem cells makes them hypertonic. It causes the movement of water into the phloem cells from adjacent xylem.
3. This increases osmotic pressure in phloem cells and phloem sap moves to the area of low pressure (that is, movement of sap occurs from source to sink along the phloem).
4. At the sink, sucrose is taken out of the phloem cells by active transport. As the amount of sugar decreases, there is a decrease in osmotic pressure that results in the movement of water out of the phloem cells.
5. Removal of water from phloem at the sink again creates a pressure gradient that causes continuous movement of sap from source to sink.

Q.16 What causes the opening and closing of guard cells of stomata during transpiration?


Stomata are small openings on leaves. Stomatal pores are surrounded by guard cells which are thick and elastic at the side of pore and thin at the opposite side of the pore. Transpiration and gaseous exchange (exchange of CO2 and O2) takes place through stomata. Stomata are open during the day and closed at night. Turgor pressure plays an important role in the opening and closing of stomata. Whenever there is an increase in turgidity of guard cells, they expand. Because of the thin outer boundary of guard cells, they bulge out, thereby opening the pore of stomata. When turgidity of guard cells decreases, they go back to their normal shape and this results in the closing of stomatal aperture.

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FAQs (Frequently Asked Questions)

1. How does transportation take place in plants?

Water and minerals enter a plant with the help of cannula vessels. In a plant, a group of cells forms a tissue. This tissue performs a specific function. Conducting tissues called xylem and phloem carry out transportation in plants. Both these tissues are vascular. While the xylem is involved with water molecule transportation, phloem aids in transporting food molecules. 

2. What is the transport system in plants?

The transport system is in three levels in plants. The first is transporting substances from one cell to another, the second level is long-distance transportation through xylem and phloem, and the third level is intake and release of solute and water by individual cells. The transport system in plants is equivalent to the circulatory system in humans.

3. What are the topics included in Chapter 11 Biology Class 11?

Plant physiology along with the transportation of water in plants are studied in-depth in Biology Chapter 11 of Class 11. A short intro to the transport of water in plants exposes students to the topic that begins the chapter. In plants, multiple types of transportation processes occur. This along with the basic knowledge about cell structure and plant anatomy is covered in the chapter. 


4. How is food transported in plants?

Food transportation occurs in plants through the phloem. The vascular tissue phloem has sieve tube elements that aid in transporting sugar. All of the sieve tube’s metabolic functions are carried through companion cells. Phloem fibres provide tensile strength and food is transferred with the help of phloem parenchyma. Food, which is in the form of organic solutes, is transported to higher plants through the process of translocation.

5. How many types of transportation are there in plants?

Transportation in plants is carried out through three different means which are diffusion, facilitated diffusion, and active transport.

6. Differentiate between xylem and phloem.

Xylem is made up of dead cells whereas phloem is made of living cells. Xylem transports water and minerals from roots to all other parts of a plant while phloem transports the food made by leaves to all parts of the plant.