Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 3.1D Movement of Water, Minerals, Food and Gases offer valuable context and analysis.
WBBSE Class 9 Science Chapter 3.1D Question Answer – Movement of Water, Minerals, Food and Gases
Very Short Questions and Answers : (1 mark for each question)
By which process water molecules enter through the cell membrane of root hair cells?
Water molecules enter through the cell membrane of root hair cells by endosmosis.
How do cells of aquatic plants absorb dissolved CO2 from water?
Aquatic plants absorb dissolved CO2 from the water by diffusion.
How is facilitated diffusion different from active transport?
In active transport, chemical energy is needed in the form of ATP but facilitated diffusion does not need energy.
In which type of active transport, two different diffusible molecules or ions move against each other at the same time?
In antiport, two different diffusible molecules or ions move against each other at the same time.
In which type of active transport, a single type of ion or molecule moves through the cell membrane?
In uniport, a single type of ion or molecule moves through the cell membrane.
In which type of active transport, two different ions or molecules move together in the same direction through a cell membrane?
In symport, two different ions or molecules move together in the same direction through a cell membrane.
Name two biomolecules, which pass through the cell membrane by active transport.
Glucose and amino acids pass through the cell membrane by active transport.
Mention two matters, which are taken into a cell by passive transport.
Oxygen and water are two matters, which are taken into a cell by passive transport.
Diffusion pressure deficit increases in leaves during daytime due to which phenomenon?
Diffusion pressure deficit increases in leaves during the daytime due to transpiration.
How does sap pass through the cells of cortex of root?
Sap passes through the cells of cortex of root by cell to cell osmosis.
Which pressure is created within the xylem vessels by the inflow of sap from the root?
Root pressure is created within the xylem vessels by the inflow of sap from the root.
Which force pulls the sap up from roots to the leaves of tall plants?
Transpiration pull helps the sap to reach the top leaves of tall plants.
How much pulling force may transpiration pull create in a xylem vessel?
About 20 atmospheric pressure is created in the xylem vessels of taller plants by transpiration pull.
How does the size of diffusible molecules affect the rate of diffusion?
Larger size of diffusible molecules reduces the rate of diffusion and vice versa.
How does the density of diffusible molecules affect the rate of diffusion?
Higher density of diffusible molecules increases the rate of diffusion.
Due to which pressure young meristematic cells grow in size?
Young meristematic cells grow in size due to turgor pressure.
Name the scientist who proposed the ‘Root Pressure Theory’.
British scientist Stephen Hales proposed the ‘Root Pressure Theory’.
Who proposed the ‘Transpiration pull and Cohesion Tension Theory’ to explain the ascent of sap?
Scientists Dixon and Joly proposed the ‘Transpiration pull and Cohesion tension theory’ to explain the ascent of sap.
Give an example of an impermeable membrane.
An example of an impermeable membrane is plastic sheet.
Give an example of a permeable membrane.
Cell wall is an example of a permeable membrane.
Give an example of a semi-permeable membrane.
An example of a semi-permeable membrane is parchment paper.
By which type of active transport, two different diffusible molecules are carried by a single carrier protein?
In coupled transport, two different diffusible molecules are carried by a single carrier protein.
Name the components of xylem, which play a major role in the transport of water.
The components of xylem, which play a major role in the transport of water are tracheid and trachea.
Short Questions and Answers : (2 marks for each question)
What is meant by transport?
The process by which food materials, mineral salts, hormones and various gases reach the cells of living organisms and different harmful metabolic waste matters are sent from tissues to respective excretory organs through liquid medium, is called transport.
How is facilitated diffusion different from simple diffusion
In facilitated diffusion, a carrier molecule or a channel protein in the membrane helps the entry of the diffusible molecules through it, but in simple diffusion, carrier protein is not required.
What is meant by passive transport?
Passive transport is a process by which any molecule or ion of a substance passes through cell membrane along concentration gradient without consuming any metabolic energy. ExampleDiffusion and osmosis.
What is meant by active transport?
Active transport is a process by which any molecule or ion needs some metabolic energy to pass through a cell membrane by the help of carrier protein, against concentration gradient. Example-Intake of glucose molecules by a cell.
What is diffusion?
The physical process by which molecules or ions of any substance, moves from a region of higher concentration to a region of lower concentration, with the help of their own kinetic energy, is called diffusion. Example-Aroma of incense stick spreads to all corners of the room by diffusion.
What is meant by osmosis?
If two solutions of different concentration, prepared from the same liquid solvent, are separated by a semi-permeable membrane, the solvent molecules move from the region of higher solvent concentration towards the region of lower solvent concentration, until equilibrium is attained. This physical phenomenon is known as osmosis. Example-Raisins swell in water due to osmosis.
What is meant by facilitated diffusion?
Facilitated diffusion is a type of diffusion, where diffusible molecules pass through a cell membrane with the help of some channel proteins present in it. In this process, no metabolic energy is needed.
What is meant by root pressure? Mention the importance of root pressure.
- Root pressure: The cumulative turgor pressure created in the cells, surrounding the xylem vessels of the root, due to absorption of sap is known as root pressure.
- Importance: Root pressure pushes the sap into the xylem vessels through their thick cell wall and drives the sap upward.
What is cohesive force? What is meant by adhesive force.
- Cohesive force: The force of attraction between two particles or molecules of a same substance, is called cohesion force. Inside the xylem vessels water droplets remain attached to each other by cohesive force.
- Adhesive force: The force of attraction between the particles of different substances, is called the adhesive force. The water droplets remain attached to the wall of xylem vessel by adhesive force.
What is transpiration pull?
In xylem vessels, uninterrupted water column is formed by cohesive-adhesive force. These columns extend from the roots to the stomata of the leaves. During transpiration, when a molecule of water leaves the stomatal opening, it applies an upward pulling force on the receding water column, which is known as transpiration pull.
What is meant by ascent of sap?
The transport of water and minerals, known as sap, from root to the leaves through xylem vessels against the force of gravity, is known as the ascent of sap.
The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire room after some time. Which phenomenon is responsible for this?
The fragrance of a perfume, sprayed at one corner of a room, can be felt in the entire room after some time due to a phenomenon called diffusion.
Name the forces which control the ascent of sap in plants.
The forces which control the ascent of sap in plants are-
- root pressure
- transpiration pull
- adhesive force and
- cohesive force.
Give two examples of liquid-liquid diffusion.
Two examples of liquid-liquid diffusion are-
- Diffusion between water and ink and
- Diffusion between water and sugar syrup.
Give two examples of liquid-solid diffusion.
Two examples of liquid-solid diffusion are-
- Diffusion between water and sugar crystal and
- Diffusion between water and copper sulphate (CuSO4)crystals.
Give two examples of solid-gas diffusion.
Two examples of solid-gas diffusion are-
- Diffusion between asafoetida and air and
- Diffusion between camphor and air.
Give two examples of gas-gas diffusion.
Two examples of gas-gas diffusion are-
- Diffusion between air and ammonia gas and
- Diffusion between air and smoke of inscence stick.
Mention two examples of carrier proteins which help in active transport.
Two examples of carrier proteins which help in active transport are-
- Sodium-Potassium pump (Na+/K+-ATPase pump) and
- Proton pump (H- ATPase pump).
Define hypertonic solution.
A solution that has a higher concentration of solutes on the outer side of a cell in comparison to the inner side of it, is known as a hypertonic solution.
What is an isotonic solution?
A solution that has identical concentration of solutes on both outer and inner side of a cell, is known as isotonic solution.
Define a hypotonic solution.
A solution that has lower concentration of solutes on the outer side of a cell in comparison to the inner side of it, is known as hypotonic solution.
What is absorption in plants?
The physical process by which water and mineral salts enter the plant body through root hair by the process of endosmosis, is called absorption.
Why the water potential of any solution is always negative?
The water potential of pure water is zero. Thus, solute mixed any solution always has negative water potential.
What are the major components of pholem sap?
The major components of pholem sap arecarbohydrate, amino acid, minerals and organic acid and water.
Mention the differences between active transport and passive transport.
|1. Metabolic Energy
|Cellular metabolic energy is requried
|Cellular metabolic energy is not required
|Play important role
|Play no role
|3. Transpiration pull
|Plays no role
|Plays major role
|4. Effect of O2
|Transport is hampered in the absence of free O2
|Transport is not effected by the absence of free O2
Mention the differences between diffusion and osmosis.
|1. Semi-permeable membrane
|Not necessary for diffusion
|Essential for osmosis
|Occurs between different media (solid, liquid, gas)
|Occurs between two liquids
|Both solute and solvent are transported
|Only solvents are transported
Long Questions and Answers : (5 marks for each question)
Mention the role of different factors in controlling diffusion.
Role of different factors in controlling diffusion
Various factors play important role in controlling the rate of diffusion. These are mentioned below.
1. Temperature: With the increase in temperature of the medium, movement of diffusible molecules increase. Therefore, increase in temperature enhances the rate of diffusion.
2. Size of diffusible molecules: Larger size of the diffusible molecules restricts their movement. Therefore, larger molecules show slower diffusion rate.
3. Extent of concentration gradient: Rate of diffusion also depends upon the concentration gradient of molecules of both media. The greater the difference in concentration, the more rapid the diffusion. The closer the distribution of both molecules gets to equilibrium, the slower the rate of diffusion becomes.
4. Solubility: A molecule with higher rate of solubility, diffuses quickly in a given medium.
5. Viscosity of the medium: The rate of diffusion is inversely proportional to the viscosity of the medium. That is, if the viscosity of the medium is high, then the rate of diffusion will be lower and vice versa.
Mention the salient features of diffusion. Give two examples of diffusion in plants.
The salient features of diffusion:
The salient features of diffusion are as follows—
- Diffusible molecules of solid, liquid or gaseous substances can diffuse within either liquid or in gaseous medium.
- Diffusible molecules move from a region of higher concentration to a region of lower concentration.
- Diffusion of molecules continues until homogeneity’ is attained, i.e. the concentration of molecules in both directions becomes same.
- It is a passive process, i.e. does not require any metabolic energy.
Example of diffusion in plants
Two examples of diffusion in plants are —
- passive absorption of ions and
- absorption of O and CO2 in cells.
What is meant by plasmolysis and deplasmotysis? What happens when a living cell is placed in a solution with concentration identical to its protoplasm?
If a cell with intact cell membrane is placed in a hypertonic solution, i.e. a solution with concentration higher than the concentration of the protoplasm of the cell, water from the protoplasm will gradually move out from the ceil through its cell membrane by exosmosis. In this case the protoplasm of the cell will shrink and the cell will appear wrrinkied. This phenomenon is called plasmolysis.
If a plasmolysed cell is placed in a hypotonic solution, i.e. a solution with concentration lower than the concentration of the protoplasm of the cell, water from the outer medium will enter into the protoplasm through the cell membrane by endosmosis. In this case, the protoplasm will get more water and the cell will be distended. This phenomenon is called deplasmolysis.
Fate of living cell in isotonic solution
If a living cell is placed in a solution with concentration identical to its protoplasm, i.e., isotonic solution, water from outer medium and from the protoplasm will move through the cell membrane at same rate against each other. Therefore, no change will appear in the cell.
Mention the salient features of osmosis. Mention three roles of osmosis in plant body.
The salient features of osmosis:
The salient features of osmosis have been mentioned below.
- Osmosis occurs only in liquid medium.
- This process involves the presence of semi-permeable membrane.
- Solvent molecules move from a region of its higher concentration to a region of lower concentration across the semi-permeable membrane. Movement of solutes does not occur in osmosis.
- Movement of solvent molecules continues until homogeneity is attained. In osmosis, rate of movement of solvent molecules on either side of the semi-permeable membrane becomes the same.
- It is a passive process, i.e. does not require any metabolic energy.
Role of osmosis in plant body
In plants, osmosis helps in-
- absorption of water,
- opening and closing of the stomata and
- maintaining turgidity of cell.
Briefly describe the characteristic features of active transport. Mention the importance of cell to cell transport.
The characteristic features of active transport:
The characteristic features of active transport has been briefly described below.
- In this process, the movement of substances occur from a region of lower concentration to a region of higher concentration.
- The cell membrane has different carrier proteins that remain suspended in its lipid bi-layer. The substances to be transported, first bind to a specific carrier protein and then passes from one side of the membrane to another.
- The movement of substances against the concentration gradient requires the involvement of energy, which is supplied by ATP. In plants, active transport occurs during absorption of mineral ions by plant roots, loading of sugar into the phloem etc.
- Active transport requires a semi-permeable membrane.
Importance of cell to cell transport:
The importance of cell to cell transport are as follows
- Diffusible materials like O2 ,CO2 etc. move from one cell to the next, by cell to cell diffusion.
- Water passes from one cell to another, by cell to cell osmosis.
- Sugar is loaded into the phloem cells from the leaf cells by means of cell to cell active transport.
How does ascent of sap occur in a plant?
Ascent of sap:
Transpiration is the process that acts as a driving force for the ascent of sap, from roots to the top of a tree, via xylem vessels. The sequence of events during ascent of sap occurs in the following order:
- Release of water through stomata by transpiration.
- Lowering of turgor pressure of leaf cells due to loss of water.
- Uptake of water by leaf cells from the xylem elements causing a vacuum in the xylem vessels.
- Generation of a vertically upward suction force on the water column in the xylem vessel, called transpiration pull.
- Cohesive and adhesive forces of water molecules maintain the uninterrupted water column within the xylem vessels.
- Roots absorb water and minerals from the soil by imbibition and endosmosis, that moves through the endodermis and increases turgor pressure in the cells surrounding the xylem vessels.
- The mounting root pressure pushes sap into xylem vessels and starts to drive it against gravity towards the leaves upwards.
How is food transported in different parts of the plant body?
Transportation of food in plant body:
Transportation of food in plants occurs through sieve tubes of phloem. The cells of selve tube are arranged one after the other forming a continuous structure. Regarding the mechanism of this process, ‘pressure flow hypothesis’ by Ernst Munch, is the most accepted one. According to this hypothesis, following events occur during food transport in plants.
1. Transfer of food from mesophyll tissue to sieve tube: In mesophyll tissues, glucose produced by photosynthesis is soon converted into a larger sugar (sucrose). The sucrose solution is then transferred to the sieve tube via bundle sheath cells, phloem parenchyma and companion cells by cell to cell transport.
2. Creation of pressure within sieve tube: With the entry of sucrose, the cytoplasm of sieve tube becomes denser. As a result, a concentration gradient develops between the sieve tube & neighbouring xylem vessels. Due to this, water moves into the sieve tube from xylem vessels by osmosis, thereby, creating additional pressure within the sieve tubes.
3. Flow of food: This mounting pressure produced within the sieve tube, pushes the food solution to different parts of the plant body. Finally, the sucrose solution enters into the tissue cells from the sieve tube.