Biology Class 11 NCERT Solutions: Chapter 11 Transport in Plants Part 1

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

Answer:

Diffusion is the passive movement of substances from a region of higher concentration to a region of lower concentration. Diffusion of substances plays an important role in cellular transport in plants. Rate of diffusion is affected by concentration gradient, membrane permeability, temperature, and pressure. Diffusion takes place as long as there is a difference between the concentrations of a substance across a barrier. However, diffusion stops, when the concentrations of the substance on either side of the barrier become equal. The permeability of a membrane affects the rate of diffusion. Diffusion rate increases as membrane permeability increases. Changes in temperature and pressure values also affect the diffusion of substances. Pressure plays an important role in the diffusion of gases as gases diffuse from a region of higher partial pressure to a region of lower partial pressure.

Image of the factors affecting the rate of diffusion

Image of the Factors Affecting the Rate of Diffusion

Image of the factors affecting the rate of diffusion

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

Answer:

Porins are types of proteins, which form pores of large sizes in the outer membranes of plastids such as chloroplast, mitochondria, and the membranes in bacteria. They help in facilitating the passive transport of small-sized protein molecules.

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

Answer:

In plant cells, active transport occurs against the concentration gradient, i.e., from a region of lower concentration to a region of higher concentration. The process of active transport involves specific protein pumps. The protein pumps are made up of specific proteins called trans-membrane proteins. These pumps first make a complex

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

Answer:

Water potential quantifies the tendency of water to move from one part to the other during various cellular processes. It is denoted by the Greek letter Psi or Ψ. The water potential of pure water is always taken as zero at standard temperature and pressure. It can be explained in terms of the kinetic energy possessed by water molecules. When water is in liquid form, the movement of its molecules is rapid and constant. Pure water has the highest concentration of water molecules. Therefore, it has the highest water potential. When some solute is dissolved in water, the water potential of pure water decreases.

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.

Answer:

(A) Diffusion and Osmosis

Q_5_A_Table of Diffusion and Osmosis
Q_5_A_Table of Diffusion and Osmosis

Diffusion

Osmosis

1.

Diffusion is the passive movement of particles, ions, and molecules along the concentration gradient.

1.

Osmosis is the process in which the diffusion of a solvent (water) occurs across a semi-permeable membrane

2.

It can occur in solids, liquids, and gases.

2.

It occurs in the liquid medium.

3.

It does not require a semi - permeable membrane.

3.

It requires a semi-permeable membrane.

4.

Image showing the diffusion

Image Showing the Diffusion

Image showing the diffusion

4.

Image showing the osmosis

Image Showing the Osmosis

Image showing the osmosis

(B) Transpiration and evaporation

Q_5_B_Transpiration and Evaporation
Q_5_B_Transpiration and Evaporation

Transpiration

Evaporation

1.

It occurs in plants

1.

It occurs from any free surface and involves living and non-living surfaces.

2.

It is a physiological process.

2.

It is a physical process.

3.

It occurs mainly through the stomatal

pores on plant leaves.

3.

It is occurs through any free surface.

4.

It is controlled by environmental factors as well as physiological factors of plants such as root-shoot ratio and number of stomata.

4.

It is entirely driven by environmental factors.

Image shows the evepotranspiration

Image Shows the Evepotranspiration

Image shows the evepotranspiration

(C) Osmotic pressure and osmotic potential

Q_5_C_Table of OsmoticPressure and Osmotic Potential
Q_5_C_Table of OsmoticPressure and Osmotic Potential

Osmotic Pressure

Osmotic Potential

1.

It is expressed in bars with a positive sign.

1.

It occurs from any free surface and involves living and non-living surfaces.

2.

It is a positive pressure.

2.

It is a negative pressure.

3.

Its value increases with an increase in the concentration of solute particles.

3.

Its value decreases with an increase in the concentration of solute particles.

(D) Imbibition and diffusion

Q_5_D_Table of Imbibition and Diffusion
Q_5_D_Table of Imbibition and Diffusion

Imbibition

Diffusion

1.

Imbibition is a special type of diffusion. In this process, water is absorbed by solids and colloids, causing an enormous increase in volume.

1.

Diffusion is the passive movement of particles, ions, and molecules along the concentration gradient.

2.

It usually involves water.

2.

It involves solids, liquids, and gases.

(E) Apoplast and symplast pathways of movement of water in plants

Q_5_E_Table of Apoplast and Symplast Pathways of Movement of Water in Plants
Q_5_E_Table of Apoplast and Symplast Pathways of Movement of Water in Plants

Apoplast pathway

Symplast pathway

1.

The apoplast pathway involves the movement of water through the adjacent cell walls of the epidermis and cortex. The movement of water is restricted at the casparian strips of the root endodermis.

1.

The symplast pathway involves the movement of water through the interconnected protoplasts of the epidermis, cortex, endodermis, and root pericycle.

2.

It is a faster process of water movement and water moves through mass flow.

2.

It is a slower process of water movement.

Image shows the Apoplast and symplast pathways

Image Shows the Apoplast and Symplast Pathways

Image shows the Apoplast and symplast pathways

(F) Guttation and Transpiration

Q_5_F_Table of Guttation and Transpiration
Q_5_F_Table of Guttation and Transpiration

Guttation

Transpiration

1.

It occurs usually at night.

1.

It occurs usually during the day.

2.

Water is lost from the leaves in the form of liquid droplets.

2.

Water is lost from the leaves in the form of water vapour.

3.

It occurs through the vein endings of leaves.

3.

It occurs through the stomata.

4.

It is an uncontrolled process.

4.

It is a controlled process.

Difference between Guttation and Transpiration

Difference Between Guttation and Transpiration

Difference between Guttation and Transpiration