RBSE Solutions For Class 12 Biology Chapter 5: Plant Water Relations | Textbook Important Questions & Answers

RBSE Class 12 Biology Chapter 5- Plant water relations, provides complete information related to diffusion, different factors affecting diffusion, significances, permeability, osmosis, types of osmosis, their significance to plants, plasmolysis, deplasmolysis and lots more related to plant and water relations.

RBSE Solutions for Class 12 help students to perform their best in the exams. By practising these important questions, students can analyze their preparation, get thorough knowledge about all the important terminologies and at the same time helps them assess their understanding of the material.

The Rajasthan Board Class 12 Biology Chapter 5 important questions are the best study material for both class assignments and other board examinations. By practising these important questions, students can gain deep knowledge about the topics explained in this chapter and also help them to be well prepared for their upcoming examinations.

RBSE Class 12 Biology Chapter 5 Important Questions

RBSE Biology Chapter 5: MCQs Type Questions

Q.1. The entry and exit of any substance within the cell depend on ________.

(a)Exosmosis.

(b)Permeability.

(c)Imbibition.

(d)Endosmosis.

Sol:(b)Permeability

Q.2. Diffusion of water from one cell to another cell in plants is maintained by ________.

(a)Endosmosis.

(b)Exosmosis.

(c)Osmosis.

(d)Diffusion.

Sol:(c)Osmosis.

Q.3. Which of the following factors affect the process of diffusion?

(a)Air.

(b)Light.

(c)Water.

(d)Temperature.

Sol:(d)Temperature.

Q.4. The exchange of CO2 and O2 from the atmosphere by leaves is called ________.

(a)Osmosis.

(b)Diffusion.

(c)Imbibition.

(d)Endosmosis.

Sol:(b)Diffusion.

Q.5. The diffusion of a solvent by semipermeable membrane is called ________.

((a)Plasmolysis.

(b)Endosmosis.

(c)Imbibition.

(d)Osmosis.

Sol: (d)Osmosis.

Q.6. Which of the following statements are true?

(a)The water potential of a distilled water is zero.

(b)The water potential of pure water is zero.

(c)The water potential of salt water is zero.

(d)The water potential of the solution is zero.

Sol:(b)The water potential of pure water is zero.

Q.7. Which of the following is the permeable membrane?

(a)Cell wall.

(b)Cuticle.

(c)Tonoplast.

(d)Cell membrane.

Sol:(a) Cell wall.

Q.8. Which of the following processes is important in seed germination?

(a)Osmosis.

(b)Diffusion.

(c)Imbibition.

(d)Plasmolysis.

Sol:(c)Imbibition.

Q.9. The value of DPD in the flaccid stage will be ______.

(a)Zero.

(b)Equal to OP.

(c)Less than OP.

(d)More than OP.

Sol:(b)Equal to OP.

Q.10. Absorption of water by the hydrophilic colloids substances are called______.

(a)Imbibition.

(b)Diffusion.

(c)Osmosis.

(d)Plasmolysis.

Sol:(a)Imbibition.

Q.11.Which of the following statements are true?

(a)Suction pressure is zero in a flaccid cell.

(b)Diffusion pressure is zero in a flaccid cell.

(c)Wall pressure is zero in a flaccid cell.

(d)Osmotic pressure is zero in a flaccid cell.

Sol:(c)Wall pressure is zero in a flaccid cell.

Q.12. Which of the following is the semi-permeable membrane?

(a)Cell wall.

(b)Cell membrane.

(c)Cuticle.

(d)Tonoplast.

Sol:Cell membrane.

Q.13. Absorption of mineral salts by plants is an example of ______.

(a)Imbibition.

(b)Diffusion.

(c)Osmosis.

(d)Plasmolysis.

Sol:(b)Diffusion.

Q.14. Which of the following statements are true?

(a)The value of osmotic pressure and osmotic potential is the zero.

(b)The value of osmotic pressure and osmotic potential is different.

(c)The value of osmotic pressure and osmotic potential is the same.

(d)The value of osmotic pressure and osmotic potential is equal to đťś‹ (pi) .

Sol:(c)The value of osmotic pressure and osmotic potential is the same.

Q.15. Which of the following is an example of Imbibition?

(a)Feeling thirsty after having salty food.

(b)Swelling of wooden doors during the rainy season.

(c)Movement of salt-water in the animal cell across our cell membrane

(d)Sugar gets dissolved evenly and sweetens the water without having to stir it.

Sol:(b)Swelling of wooden doors during the rainy season.

Q.16. Which of the following is an example of diffusion?

(a)Transpiration.

(b)Exchange of gases.

(c)Opening of bud into a flower.

(d)Absorption of water by roots,

Sol:(b)Exchange of gases.

Q.17. ______ regulates the flow of substances from within to outside of the cell.

(a)Plasmolysis

(b)Imbibition

(c) Deplasmolysis

(d) Permeability

Sol:(d) Permeability

Q.18. What is the water potential of a pure water?

(a) Zero.

(b) Less than zero.

(c) Less than one.

(d)More than zero and less than one.

Sol:(a) Zero

Q.19. Which of the following statements are true?

(a)The osmotic pressure is proportional to the molar concentration of a solution.

(b)The osmotic pressure is proportional to the total number of solute particles present in it.

(c)The osmotic pressure is proportional to the rate of diffusion.

(d)The osmotic pressure is proportional to the ionic concentration.

Sol:(b)The osmotic pressure is proportional to the total number of solute particles present in it.

Q.20. The value of the osmotic pressure is always ______.

(a)Zero.

(b)Less than zero.

(c) Positive.

(d) Negative.

Sol: (c) Positive.

RBSE Biology Chapter 5:Short Answer Type Questions.

Q.1. Give the importance of osmosis.

Sol. In plants, osmosis processes play an important role in transportation. Listed below are the importance of osmosis :

  1. Helps in the turgidity of plant cells.
  2. Helps roots in the absorption of water from the soil.
  3. Helps in the transportation or distribution of water to various parts of the plants.

Q.2.Define Imbibition.

Sol: Imbibition is the process of water absorption by substances without forming a solution. For eg., swelling of seeds immersed in water. The substance which absorbs water is called imbibant.

Q.3. Explain the water potential in plants.

Sol: Water potential is the energy required by plants for transporting an infinitesimal quantity of water. Greater the concentration of water in a system, greater is its kinetic energy and greater is the water potential. Water potential of pure water is zero and is measured in Pascal (Pa)

Q.4. What is TP and WP?

Sol. TP refers to turgor pressure. It is the pressure developed inside the plant’s cell. When water enters the plant cell, the cytoplasm builds up a pressure against the cell wall and cells enlarge. This pressure is called turgor pressure.

WP refers to wall pressure. It is the force exerted by the cell wall against the turgor pressure.

Overall, Wall pressure (WP) is equal to Turgor pressure (TP).

Q.5. What is Endosmosis?

Sol. Endosmosis is defined as the movement of the water molecules inside the cells when the cell is placed in a hypotonic solution. This movement of water causes the cell to swell.

Q.6. What is semipermeable membrane? Give examples.

Sol: The layer or the membranes, which are permeable only for the solvents and impermeable for other solute molecules are called semi permeable membranes. Example- Cell membrane, plasma membrane, etc.

Q.7. Write the differences between endosmosis and exosmosis.

Sol: Endosmosis is defined as the movement of the water molecules inside the cells when the cell is placed in a hypotonic solution, whereas, exosmosis is defined as the movement of water outside the cells when a cell is placed in a hypertonic solution.

Q.8. Define Osmosis?

Sol: Osmosis is defined as the movement of molecules from a region of lower concentration to a region of higher concentration. Osmosis can be of two types- endosmosis and exosmosis.

Q.9. What is Exosmosis?

Sol: Exosmosis is defined as the movement of water outside the cells when a cell is placed in a hypertonic solution. The cell becomes flaccid by the movement of water outside.

Q.10. What is the hypothesis of water potential? Who presented the concept of water potential?

Sol: Water potential is defined as the difference between the free energy of water molecules in pure water and the free energy of water molecules in a solution. It is expressed by the Greek letter Ψ (Psi) and the unit of water potential is pascal(Pa). The concept of water potential was first presented by R.K.Slatyer and S.A Taylor in 1960.

Q.11.How turgidity is useful for plants?

Sol: In plants, turgidity is useful in:

  1. Maintaining the rigidity of the cell.
  2. Helps in movement of phloem sap.
  3. Helps in opening of the stomata by the guard cells.
  4. Essential for maintaining the shape and normal growth of cells.
  5. Makes the surface of the leaf properly available to sunlight by proper orientation.

Q.12. What are the factors affecting imbibition in plants?

Sol. The factors affecting the process of imbibition in plants are:

  1. Pressure.
  2. pH of a medium.
  3. Texture of an imbibant.
  4. Affinity of the imbibant for the imbibant.

Q.13. Why is osmosis important for the cells?

Sol: Osmosis is important for the cells for many reasons. It helps in the movement of important materials inside and out of the cell. The nutrients, water and other solutes move in and out of the cell by the process of osmosis.

Q.14.What is the difference between imbibition and osmosis?

Sol: Imbibition is the process of water absorption through a solid substance, whereas, osmosis is the process of movement of water from higher concentration to lower concentration through a semipermeable membrane.

Q.15. What are the factors affecting diffusion?

Sol. The factors affecting the process of diffusion include:

  1. Temperature.
  2. Area of interaction.
  3. Size of the particle .
  4. The steepness of the concentration gradient.

Q.16. How is osmosis different from diffusion?

Sol: Osmosis is a process of movement of solvents through a semipermeable membrane from a region of lower solute concentration to higher solute concentration. On the contrary, diffusion does not require a semi-permeable membrane to occur and the molecules move from a region of higher concentration to lower concentration.

Q.17. Give a few examples of imbibition.

Sol: A few examples of imbibition are:

  • Germination of seeds.
  • Absorption of water by roots.
  • The swelling of soaked seeds.
  • The swelling of a wooden door during rains.

Q.18. State the significance of diffusion.

Sol: Diffusion is quite important as it affects many life processes. All living organisms exhibit one or the other form of diffusion, allowing the movement of the molecules during various metabolic or cellular processes.

Q.19.What are the factors affecting the rate of osmosis?

Sol. The factors affecting the rate of osmosis include:

  1. Pressure.
  2. Temperature.
  3. Surface Area.
  4. Water Potential.
  5. Concentration gradient.

Q.20. How is imbibition different from diffusion?

Sol: Imbibition is a reversible process whereas diffusion is an irreversible process. Imbibition is the absorption of water by the general surface, whereas diffusion is the movement of solid, liquid or gaseous molecules from the region of higher concentration to lower concentration.

RBSE Biology Class 12: Long Answer Type Questions

Q.1.Explain in detail about plasmolysis and deplasmolysis.

Sol. Plasmolysis is defined as the process of contraction or shrinkage of the protoplasm of a plant cell and is caused due to the loss of water in the cell. Plasmolysis is one of the outcomes of osmosis and rarely occurs in nature. There are two different types of plasmolysis and this classification is mainly based on the structure of the cytoplasm.

Shrinkage of vegetables and blood cells, when placed in hypertonic conditions are the best examples of plasmolysis.

De-plasmolysis is defined as the reversal process of plasmolysis. When the plasmolysed cell is placed in a hypotonic solution, the water travels into the cell, swells and becomes turgid. This is due to the presence of a higher concentration of water outside the cell.

Q.2.Write the differences between diffusion and osmosis.

Sol. Differences between diffusion and osmosis:

Diffusion Osmosis
Occurs only in the liquid state. Occurs in all three states of matter – solids, liquids or gases.
Movement of water molecules from higher water concentration area to the area of less water concentration The net movement of substances from higher concentration area to lower concentration area.
Applied only for the solvent part of the solution. Applied to all three states of matter.
Requires semipermeable membrane. Does not require semipermeable membrane.
Depends on the rate of reduction of free energy of one solvent. Depends on the free energy of the substance.
Influenced by the solute potential Not influenced by a solute potential
It is opposed by hydrostatic or turgor pressure Hydrostatic pressure or turgor pressure will not occur in diffusion.
The concentration of the solvent is not equalized. The concentration of the whole substance will be equalised.

Q.3.List out the Importance of osmosis, diffusion and imbibition.

Sol.

Osmosis plays an important role in:

  1. Cell division.
  2. Growth of cells.
  3. Seed germination.
  4. Opening and closing of stomata.
  5. Distribution of water from cell to cell.

Diffusion plays an important role in:

  1. Pollination.
  2. Transpiration.
  3. Photosynthesis.
  4. Movement of molecules within plants.

Imbibition plays an important role in:

  1. Seed germination.
  2. Excretion of heat.
  3. Absorption of water by seed.

Q.4. Define Osmosis, Types of Osmosis and Osmotic Solutions.

Sol.

Osmosis

Osmosis is a passive process and happens without any expenditure of energy. It involves the movement of molecules from a region of higher concentration to lower concentration until the concentrations become equal on either side of the membrane.

Types of Osmosis

There are two different types of osmosis:

  1. Endosmosis– When a substance is placed in a hypotonic solution, the solvent molecules move inside the cell and the cell becomes turgid or de-plasmolyzed.
  2. Exosmosis– When a substance is placed in a hypertonic solution, the solvent molecules move outside the cell and the cell becomes flaccid or plasmolyzed.

Types of Osmotic Solutions

There are three different types of solutions:

  1. Isotonic Solution – The solution with the same concentration of solutes both inside and outside the cell.
  2. Hypertonic Solution-The solution, which has a higher solute concentration outside the cell than inside.
  3. Hypotonic Solution-The solution, which has a higher solute concentration inside the cell than outside.

Q.5. Describe the role of osmosis, diffusion and imbibition in plant physiology.

Sol:

Diffusion is a process where molecules of materials move from an area of high concentration to an area of low concentration until it has reached equilibrium.

In the plant physiology, diffusion plays an important role in:

  1. Mineral uptake.
  2. Translocation of organic solutes.
  3. Movement of molecules within plants.
  4. Removal of excess water through transpiration.
  5. Also in the biological process of photosynthesis, pollination and in cellular respiration.

Osmosis is the spontaneous net movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration from the region of lower solute concentration to equalize the solute concentrations on the two sides.

In the  plant physiology, osmosis plays an important role in:

  1. Cell division.
  2. Growth of cells.
  3. Seed germination.
  4. Giving firmness to the cell.
  5. Opening and closing of stomata.
  6. Controlling the rate of transpiration.
  7. Distribution of water from cell to cell.
  8. Absorption of water from the soil by the root hair cell.

Imbibition is the process of water absorption by substances without forming a solution.

In the plant physiology, imbibition plays an important role in:

  1. It keeps the cell moist and hydrated.
  2. Helps in the absorption of water by seed.
  3. It is the first step in germination of seeds.
  4. Releases excess of heat in the form of heat energy.
  5. The seedlings emerge out of the soil and establish themselves through Imbibition.

Q.6. Write the differences between osmosis, diffusion and imbibition.

Sol: Differences between osmosis, diffusion and inhibition:

Osmosis Diffusion Imbibition
The movement of only the solvent from the region of higher concentration to the region to lower concentration. The movement of molecules from the region of higher concentration to lower concentration. It is the absorption of water by the general surface.
Occurs only in the liquid state. Occurs in all states of matter. Occurs only in the liquid state.
It is an irreversible process. Irreversible process. It is a reversible process.
Requires semi-permeable membrane. There is no requirement for a semi-permeable membrane. An absorbent is involved but there is no membrane.
It takes place only for the solvent part of the solution. It takes place in solids, liquids and gases. It takes place in both living and dead cells.

Q.7. Write the differences between plasmolysis and deplasmolysis.

Sol. Differences between plasmolysis and deplasmolysis:

Plasmolysis Deplasmolysis
The cells shrink due to plasmolysis. The cells swell due to deplasmolysis.
Occurs during exosmosis. Occurs during endosmosis.
The osmotic pressure of the cell is very low. The osmotic pressure of the cell is high.
Water molecules move out of the cell. Water molecules move into the cell.
Occurs when cells are placed in a hypertonic solution. Occurs when cells are placed in a hypotonic solution.
Occurs when the solute concentration of the surrounding solution is higher than that of the cytoplasm. Occurs when the solute concentration of the surrounding solution is less than that of the cytoplasm.
Occurs when the water potential of the surrounding solution is less than that of the cytoplasm. Occurs when the water potential of the surrounding solution is higher than that of the cytoplasm.

Q.8. What is Imbibition? Write the importance of Imbibition to plants.

Sol: Imbibition is the process of water absorption by substances without forming a solution. It is a reversible process. In plants, it helps in:

  1. Germination of seeds.
  2. Absorption of water by seed.
  3. Keeping the cell moist and hydrated.
  4. Releases excess of heat in the form of heat energy.

Q.9.Demonstrate the process of osmosis by the thistle funnel experiment.

Sol. As demonstrated in the below diagram, the inverted thistle funnel is filled with the sugar solution and the mouth or the opening of the flask is tied tightly with parchment paper. This paper works as the semipermeable membrane and allows only the solvent molecules to pass through it. The complete apparatus is placed in the beaker filled with water. After some time, the water in the thistle funnel starts to diffuse through the parchment paper. Thereby, the amount of solution present in the thistle funnel increases.

Listed below is the demonstration of the osmosis process by the thistle funnel experiment.

Thistle funnel experiment

Q.10.Write the differences between hypertonic and hypotonic solutions.

Sol. Differences between hypertonic and hypotonic solutions:

Hypertonic Solutions HypotonicSolutions
Water molecules move inside the cell from outside. Water molecules move from inside to outside the cell.
The outside solution is less concentrated than inside the cell. The outside solution has higher soluble concentration than inside the cell.
The concentration of a solution is more than the cell sap or that inside a cell. The concentration of a solution is less than the cell sap or inside of a cell.
A plant cell undergoes plasmolysis in a hypertonic solution. A plant cell becomes turgid when putting in a hypotonic solution.

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