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Important Questions for CBSE Class 11 Biology Chapter 11 - Transport in Plants

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CBSE Class 11 Biology Chapter-11 Important Questions - Free PDF Download

Free PDF download of Important Questions with Answers for CBSE Class 11 Biology Chapter 11 - Transport in Plants prepared by expert Biology teachers from latest edition of CBSE(NCERT) books. Register online for Biology tuition on Vedantu.com to score more marks in your examination.


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

1 Marks Questions:

1. Write names of two anti-transpirants?

Ans: Abscisic acid and Phenyl mercuric acetate.


2. What do you mean by translocation?

Ans: Translocation is the transportation of food from leaves to other parts of the plant through phloem vascular tissue.


3. When does wilting occur in different parts of the plant?

Ans: Wilting of plant parts occurs when the rate of transpiration increases than the rate of water uptake by roots of the plant.


4. Which two factors affect the potential of water in plants?

Ans: External pressures as well as amount of solute.


5. What are plasmodesmata?

Ans: Plasmodesmata are the connection between protoplasms of the adjacent cells.


6. What is the reason behind adding more salt to the pickles?

Ans: High salt concentrations prevent the spoilage of pickles by preventing the growth of microorganisms in them.


7. Which factor decides the direction of water flow from one cell to another?

Ans: The water potential of the cell decides the direction of water flows from one cell to another. 


8. What is guttation?

Ans: Guttation is the loss of liquid water from the plant.


9. The water potential of pure water is equal to which value?

Ans: The water potential of pure water is zero bars.


10. Which root part is responsible for water absorption?

Ans: Root hairs are present on the surface of the root that is responsible for water absorption. 


11. Which process causes swelling of raisins when they are kept in water?

Ans: Endosmosis causes swelling of raisins when they are kept in water.


12. Name the substance that forms a Casparian strip that is impermeable to water.

Ans: Suberin forms a Casparian strip and it is impermeable to water.


13. How does the addition of solute to water change the water potential?

Ans: The addition of solute to water decreases its water potential.


14. A plant cell is plasmolyzed when kept in a solution. What will be the nature of the solution in which the cell was kept?

Ans: The solution was hypertonic.


15. Write the names of two pathways by which plants absorb water through their root hairs.

Ans: Symplast pathway and Apoplast pathway.


16. Which sugar type is transported through phloem?

Ans: Sucrose is a type of sugar that is transported through the phloem.


17. Provide an example of imbibitions.

Ans: The seed swells up when placed in water or moist soil.


18. In an earthen pot, a flowering plant is planted, irrigated and then urea is added to it so that the plant can grow faster. But the plant died after some time. What could be the possible reason for this?

Ans: The plant died due to excess coming out of water i.e. exosmosis.


19. What is the requirement of energy for developing pressure in roots?

Ans: All living cells require energy for their activity. So are the root cells, they also need the energy to develop pressure in the roots.


2 Marks Questions:

1. Why is the living cell considered the osmotic system?

Ans: A living cell is also known as the osmotic system because of the following reasons:

i. It has all the parts required for an osmotic system like the semi-permeable membrane and concentration gradient of sap among the semi-permeable membrane. 

ii. Water flow occurs from high water potential towards low water potential.


2. Differentiate between active and passive transport.

Ans: Differences between active and passive transport are given below:

Active Transport

Passive Transport

1.

It is a rapid process as compared to passive transport.

1.

As compared to active transport, it is a slow process.

2.

Active transport requires energy.

2.

Passive transport does not require energy.

3.

This is a vital process.

3.

This is a physical process.

4.

Molecules move only in one direction.

4.

Molecules move in both directions.

5.

This movement requires carrier proteins.

5.

This movement does not require carrier proteins.

6.

Metabolites move against the concentration gradient.

6.

Metabolites move along the concentration gradient.


3. What are the major purposes of transpiration?

Ans: The major purposes of transpiration are given below:

i. Transpiration provides water for the photosynthesis process.

ii. Transpiration supplies minerals and water to all the plant parts from the soil.

iii. By transpiration, the leaf surface also gets cooldown by 10-15°C.

iv. It keeps the cells turgid, therefore, maintains the structure and shape of the plant.


4. Write down the significance of plasmolysis.

Ans: Following are some of the significances of the plasmolysis:

i. The process of osmosis can be explained with the help of plasmolysis.

ii. It helps to know the biotic nature of the living cell.

iii. Required to kill the weeds.

iv. The osmotic pressure of cells can be determined by plasmolysis.

v. It explains the permeability of the cell wall.


5. Why is the photosynthesis system of C4 plants more beneficial than the photosynthesis system of C3 plants?

Ans: The C4 photosynthetic system was evolved to maximizing the availability of carbon dioxide whereas to minimizing the loss of water. C4 plants are two times more efficient as compared to C3 varieties based on the process of carbon fixation. In C4 plants, to fix one gram of CO2 molecule it loses only 300 g of water by the process of evaporation while the C3 plants lose 600 g of water for the same grams of carbon dioxide to get fixed.


6.  Differentiate between the process of evaporation and transpiration.

Ans: Following are the difference between transpiration and evaporation:

Transpiration

Evaporation

1.

Transpiration is the physiological process in which water loss occurs through aerial parts of plants.

1.

Evaporation is a simple physical process but not a physiological process.

2.

Transpiration occurs in the daytime.

2.

Evaporation takes place throughout the day as well as at night.

3.

The activity of guard cells around stomatal pores regulates the process of transpiration.

3.

It is not regulated by any type of plant cell.


7.  What are two major required conditions for imbibitions to take place?

Ans: Following are the required conditions for imbibitions to take place:

i. There must be a gradient of water potential between the surface of absorbent and the water to be imbibed.

ii. There must be an affinity between the surface of absorbent and the water to be imbibed.


8. Which factors affect the diffusion rate?

Ans: The following factors affect the diffusion rate in a plant:

i. The concentration gradient

ii. Cell membrane permeability

iii. Pressure

iv. Temperature


9. What role does the osmotic pressure play to control the potential of water in the plant cells?

Ans: The pressure required to stop the movement of water into the solution from outside is known as the osmotic pressure. There is no osmotic pressure in the solution which is not covered with the semi-permeable membrane. But that solution has the potential which can be converted into osmotic pressure when placed in an osmometer.


10. Why does wilting occur during the afternoon in a well-watered herbaceous plant which is grown in a pot?

Ans: The transpiration rate in the plant increases as compared to the rate of water absorption during the afternoon. Due to this, the turgidity of plant cells causes wilting of the plant.


11. Does the rate of transpiration become the same in the plants sown in the same type of soil at a particular time? Justify your answer.

Ans: The rate of transpiration does not depend on the type of soil but depends on the number and distribution of stomata on the leaf surface.


12. What are the differences between transpiration and guttation? Explain two points.

Ans: Some of the differences between transpiration and guttation are given below:

Transpiration

Guttation

1.

Water loss in plants in the form of vapors.

1.

Loss of liquid droplets from the plants.

2.

Transpiration occurs through the stomatal pores of leaves or young stems.

2.

Guttation occurs at the tips of leaves and their margins.


3 Marks Questions:

1. Describe the hypothesis of pressure flow for the transportation of sugars in the plants.

Ans: The pressure-flow hypothesis is one of the most accepted mechanisms for the supply of sugars from the source (leaves or other photosynthetic parts) to the sink (other parts of the plant). The synthesis of glucose occurs at the source or in the leaves where it is converted into sucrose. The sucrose is first transferred to the companion cells of phloem and then to the sieve tubes using energy (active transport). The loading of sucrose at the site of the source creates a hypertonic situation in the phloem which is a vascular tissue of the plant.


2. Why does pure water have maximum water potential?

Ans: Following are the reasons for the maximum water potential of pure water:

i) Water molecules have a constant motion, hence, have kinetic energy in both liquid and gaseous phases. 

ii) The kinetic energy of the water potential is directly proportional to the concentration of water in a system.

iii) Pure water has the greatest water potential. 

iv) When two water-containing systems are in contacts such as soil and air or cell and the solution, then there occurs the random movement of water molecules from high energy systems to low energy systems. The water molecules move from a system containing high water potential water to a low water potential system at equilibrium.

v) Water potential is expressed in the units of pressure i.e. Pascal and represented as Psi or Ψ. At a particular temperature and pressure, the water potential of pure water is equal to zero.

vi) The water potential of any solution is lower than that of pure water because the dissolution of a solute with pure water lowers its concentration and thereby lowers the water potential.


3. Describe facilitated diffusion.

Ans: Facilitated diffusion is also referred to as career-mediated diffusion or carrier protein transport. This occurs according to a concentration gradient supported by the carrier protein, for example, diffusion of glucose in Red Blood Cells (RBCs). The cell membrane acts as a site for some molecules to cross the membrane. It does not establish a concentration gradient. Even if promoted by the protein-membrane, without consuming the energy of ATP, there is a concentration gradient so that the molecules are diffused. Due to the input of energy, it can cause the net transport of molecules from low to high concentrations. The maximum transport rate is reached when all protein transporters are used. It is very specific and allows the cell to select the strand on the protein side. The facilitated diffusion is stereospecific as permeases are present as the carrier proteins.


4. What is the water potential and what are the factors affecting the water potential?

Ans: Water potential is the chemical energy or chemical potential of the water which is measured in pressure terms and affected by pressure and concentration gradient. It refers to the free energy of water molecules. It is represented by the sign of psi (Ψ). Water potential is zero for pure water. This water potential is the total of solute potential, matric potential, and pressure potential [Ψ = Ψm + Ψs + Ψp]. The movement of water occurs from high water potential to low water potential. 

When the hydrostatic pressure increases, the water moves from outside into the cell. The difference between outside and inside pressure of the cell is reduced that increases the solute pressure (Ψs). The movement of water from outside towards inside the cell occurs due to the gradient of water potential.

The factors affecting water potential are given below:

a. Solute potential (Ψs)

b. Matric potential (Ψm)

c. Pressure potential (Ψp)

The solute potential is represented by Ψs and is always negative whereas the pressure potential is mostly positive and denoted by Ψp. Therefore, water potential is mainly affected by the solute pressure and pressure potential because of Ψ = Ψs + Ψp.


5. Differentiate between diffusion and imbibitions.

Ans: Differences between imbibition and diffusion are given below:

Diffusion

Imbibitions

1.

Occurs in all phases - Solids, liquids, and gases.

1.

Occurs in both living and dead cells.

2.

It is the movement of molecules, ions, and other compounds from higher to lower concentrations. 

2.

It is the process of water absorption by a smooth surface.

3.

A semipermeable membrane is not required.

3.

There is an absorbent present but there is no membrane present.

4.

Irreversible process.

4.

Reversible process.


6. Explain the plant cell as an osmotic system.

Ans: The plasma membrane of plant cells alone or along with the vacuolar membrane and the cytoplasmic film is semi-permeable in nature. This membrane allows the free passage of water molecules but prevents the entry of certain molecules. In-plant cells, the cytoplasm is surrounded by a cell wall that is highly concentrated than the solution, which enters plant cells through osmosis. Therefore, plant cells function like the osmotic system if they meet the following two conditions: 

i. If there is a semipermeable membrane. 

ii. Since it has a much higher concentration of a liquid substance, hence, plant cells act as an osmotic system.


7. What is the procedure of controlling the opening and closing of the stomatal pores?

Ans: The following factors control the opening and closing of the stomata:

a. Light: The intensity of light must be low for the opening of the stomatal pore. The stomatal pore opens up in the light and remains closed in the dark. The stomatal pore remains closed in the light and opens up in the dark in the case of CAM plants.

b. Temperature: The stomatal pore remains closed at low temperature but opens up when the temperature is high.

c. Water Availability: In water stress and water-deficient condition, the stomata remain closed.

d. Carbon Dioxide Concentration: The stomatal pore remains closed in a high concentration of carbon dioxide even when there is sufficient light. The pore opens up when the carbon dioxide is used up by the plant and its concentration decreases.


8. What are the differences between temporary and permanent wilting? Do any of these wilting indicate the status of water in the soil?

Ans: Differences between temporary and permanent wilting:

Temporary Wilting

Permanent Wilting

1.

Plants can be recovered after some time if they are influenced by temporary wilting.

1.

In permanent wilting, plants are not recovered automatically but are sometimes recovered if water is provided immediately.

2.

Plants are not much damaged.

2.

Plants are very damaged.

3.

Usually occurs in the middle of the day.

3.

Occurs throughout the day and night.


Water content in the soil decreases in large amounts when there is permanent wilting. Depending on the soil texture, only 10-15% water is present in the soil.


9. Answer the following questions after observing the given picture.

(a) Name the process occurring in (I), (II), and (III) in the given figure.

(b) What are the differences between processes II and III. 

(c) The water channels in the cell membrane are formed by how many types of aquaporins?

(Image will be uploading soon)

Ans: 

(a) Process (I) Is uniport, process (II) is antiport and process (III) is symport.

(b) Process (II) is antiport in which molecules move in the opposite direction at the same moment and process (III) is symport in which one type of molecule moves in the same direction across the cell membrane irrespective of other types of molecules.

(c) Eight types of aquaporin proteins from the water channel.


10. Write down the scientific term for each of the following processes:

(a) Exclusive water movement in the roots through the cell wall.

(b) The positive hydrostatic pressure produced inside the cell or cell wall.

(c) The comparatively less concentrated solution.

(d) The water loss in the vapor form from the aerial plant parts.

(e) Movement of one type of molecule in the same direction across the cell membrane irrespective of other types of molecules.

(f) In herbaceous plants, loss of water in the liquid phase from the margins or special openings of veins near the leaf tips.

Ans: 

(a) Apoplast pathway

(b) Turgor pressure

(c) Hypotonic solution

(d) Transpiration

(e) Uniport

(f) Guttation


5 Marks Questions

1. Explain the cohesive force theory of the ascent of sap in plants.

Ans: 


Ascent of Sap


Dixon & Jolly proposed the cohesive force theory or transpiration pull theory. The main aspects of this theory are: 

i. Strong Cohesive Force or Tensile Strength of Water: There is a mutual force of attraction between the water molecules which is known as 'cohesive force'. The force of attraction between the wall of the element of xylem and water molecules is called adhesion. The cohesive force is the force that helps to maintain a long column of water under tension. 

ii. Continuity of water column in plants: Blocking of air can maintain the total cohesive system. The rapid flow of tree sap is maintained by trees without disturbing the entire flocculation system. Water or sap can be pulled with transpiration ability. 

iii. Tensile or tension due to transpiration in an intact water column: The process of transpiration results in the drawing of water from mesophyll cells to the intercellular space and as a result, water is continuously infiltrated from nearby cells Water is attracted and diffused and lack pressure or suction power was developed. By suction, adjacent cells hold water from the barrels of the leaf. Because these barrels are connected to the root barrels via stem barrels, tension is established on the water column of the barrel, which physically raises the entire column.


2. Water absorption from the soil with the help of root hairs involves which types of forces?

Ans: 

(a) Due to transpiration pulled by aerial plant parts, a negative pressure is exerted down the roots that decrease the water potential of roots that favors the water uptake of soil.

(b) The soil favors the water absorption from the soil caused by a decrease in water potential in the root cell.

(c ) The cohesive force between the water molecules and the adhesive force between the water and the xylem cells keeps the pillar of water unbroken in the capillary of the xylem vessel. There exists a gradient of the water potential in the xylem vessel which prefers to absorb water from the soil starting from roots to leaf. 

(d) Soil water enters the root hairs, from which it reaches the xylem vessel, which has low water potential. As a result, root pressure is formed. This root pressure pushes water to the aerial plant parts.


3. What is transpiration? Why is the use of transpiration? Write any three environmental factors that affect transpiration.

Ans: Transpiration is the process of loss of water in the form of water vapors from aerial plant parts. It is a naturally occurring process. It is useful to plants in many ways:

(a) Xylem sap moves with the help of transpiration.

(b) The surface of the leaf cools down with the help of transpiration and thus protects the leaf from intense sunlight.

Following factors affect the transpiration process:

(a) Humidity/Moisture: In high humidity, water is lost slowly in the atmosphere.

(b) Temperature: With a 10°C rise in temperature, the transpiration rate doubles up.

(c) Speed of wind: Dry and high-speed wind increases transpiration.


Important Related Links for CBSE Class 11 

FAQs on Important Questions for CBSE Class 11 Biology Chapter 11 - Transport in Plants

1. What are the main topics covered in the Chapter 11 Transport in Plants of Class 11 Biology  ?

Students will study different topics related to the process of transportation of minerals, waters, and food substances to the various parts of the plant. Students will study how the transport of water takes place in distant parts. They will also study transpiration, factors affecting transpiration, and the importance of transpiration. Students will also learn how xylem and phloem help in the transport of food nutrients, water, and minerals to the different plant parts in Chapter 11 Transport in Plants of Class 11 Biology. 

2.  What do you understand by transport in plants according to Chapter 11 Transport in Plants of Class 11 Biology?

Plants that do not have a circulatory system still transport minerals, water, and food nutrients to distant parts. The water is absorbed by the roots from the soil and it reaches the different parts of the plant. Food is prepared in the leaves of the plants but food also reaches the most distant part of the plant. Transport of substances is carried out in plants to long distances through the vascular system which includes the xylem and phloem. 

3. Write a note on wilting of plants according to the Chapter 11 Transport in Plants of Class 11 Biology?

Wilting is a condition in which the leaves of a plant do not remain turgid. This causes folding, drooping, and rolling of leaves and other soft parts of the plant. Wilting occurs when more water is lost during transpiration than absorbed by the roots. Wilting may occur for a short period called temporary wilting or forever and is called permanent wilting. Temporary wilting occurs during the daytime when there is strong sunlight. Permanent wilting may occur when the loss of water during transpiration is much higher than absorption by the roots. 

4. Name the tissues that transport minerals and food in plants according to Chapter 11 ‘Transport in Plants’ of Class 11 Biology?

In plants, food and minerals are transported in different ways. Single cells uptake and release water and other solutes through the process of diffusion and osmosis. Minerals and water molecules are also transported to the plant parts using short-distance transport methods. The two most important tissues responsible for transporting substances to the distant plant parts include the xylem and phloem. Xylem and phloem are also called vascular systems of the plant. They help in transporting necessary substances even to the tip of the roots buried deep under the earth. 

5. Discuss why is transpiration important for plants according to Chapter 11 Transport in Plants of Class 11 Biology?

Transpiration is an important process that occurs naturally. It is a process during which excess water gets evaporated from the exposed parts of the plant. It helps in maintaining the proper shape and texture of the plants. But, excess transpiration is not good for plants. If excess transpiration takes place it makes the leaves droop and wilt. This occurs when roots are not able to absorb the required amount of water from the soil and the rate of transpiration is more.