Question 1

Question 2Define the following terms:(a) Imbibition(b) Diffusion(c) Osmosis(d) Osmotic pressure(e) Active transport(f) Tonicity(g) Root pressure

Accepted Answer

(a) Imbibition — Imbibition is a phenomenon by which the living or dead plant cells absorb water by surface attraction. Its the passive absorption of water by substances such as cellulose (in cell wall) and starch.(b) Diffusion — Diffusion is the free movement of molecules of a substance (solute or solvent, gas, liquid) from the region of their higher concentration to the region of their lower concentration when the two are in a direct contact.(c) Osmosis — Osmosis is the movement of water molecules from their region of higher concentration (dilute solution or with a lower solute concentration) to their region of lower concentration (concentrated solution or with a higher solute concentration) through a semi permeable membrane.(d) Osmotic pressure — Osmotic pressure is the minimum pressure that must be exerted to prevent the passage of the pure solvent into the solution when the two are separated by a semi-permeable membrane.(e) Active transport — Active transport is the passage of a substance from its lower to higher concentration through a living cell membrane using energy from the cell.(f) Tonicity — Relative concentration of the solutions that determine the direction and extent of diffusion is called tonicity.(g) Root pressure — The upward flow of water due to heavy pressure from the roots is called root pressure. Thus, it is one of the forces to raise water up through the stem into the leaves.

Question 2

Question 6Which of the following creates a suction force in plants ?TransportationTranslocationTranspirationTransformation

Accepted Answer

TranspirationReason — Transpiration (loss of water through plant surface) creates a suction force called transpiration pull. It works with root pressure due to which the roots absorb water.

Question 3

Question 9Addition of salt to pickles is a method of killing the bacteria by :ImbibitionDiffusionDeplasmolysisPlasmolysis

Accepted Answer

PlasmolysisReason — Adding salt to the pickle increases the concentration of solute outside the cells of bacteria. This results in movement of water outwards from the cell and thus bacteria gets killed.

Question 4

Question 10Root pressure can be measured by using :SphygmomanometerBarometerManometerThermometer

Accepted Answer

ManometerReason — Manometer is the instrument to measure root pressure.

Question 5

Question 11Two plant cells are placed in two different liquids and observed after 4-6 hours.CellLiquidChange in the shape of plant cellPWaterSwollenQSugar solutionShrunkenIdentify the correct pair of the processes happening in plant cells P and Q.P - Plasmolysis, Q - DeplasmolysisP - Plasmolysis, Q - TurgidityP - Exosmosis, Q - EndosmosisP - Endosmosis, Q - Exosmosis

Accepted Answer

P - Endosmosis, Q - ExosmosisReason — Plant cell P is placed in water, so the concentration of water molecules inside the cell is less than the surrounding, hence water molecules enter the cell causing the cell to swell up. Plant cell Q is placed in sugar solution, so the concentration of water molecules inside the cell is more than the surrounding, hence water will move out of the cell and as a result it will shrink.

Question 6

Question 1Differentiate between the following :(a) Plasmolysis and Deplasmolysis(b) Turgor Pressure and Wall Pressure(c) Hypotonic and Hypertonic solution(d) Turgidity and Flaccidity

Accepted Answer

(a) Difference between Plasmolysis and DeplasmolysisPlasmolysisDeplasmolysisIt refers to the shrinkage of the cytoplasm and withdrawal of the plasma membrane from the cell wall caused due to the withdrawal of water when placed in a hypertonic solution.Deplasmolysis is the recovery of a plasmolysed cell when it is placed in water, wherein the cell's protoplasm again swells up due to the re-entry of water.In Plasmolysis, the cell becomes flaccid.In Deplasmolysis, the cell becomes turgid.(b) Difference between Turgor pressure and Wall pressureTurgor PressureWall PressureTurgor pressure is the pressure of the cell contents on the cell wall.Wall pressure is the pressure exerted by the cell wall on the cell content.It helps keeps plant stems erect, keeps leaves expanded, involve in opening and closing of stomata, etc.It helps maintain the structure of cells and the plant.It acts towards the outside from the cell.It acts towards the inside of the cell.(c) Difference between Hypotonic and Hypertonic solutionHypotonic SolutionHypertonic SolutionThe solution outside the cell has a lower solute concentration than the fluids inside the cell.The solution outside the cell has higher solute concentration than the fluids inside the cell.Endosmosis occurs as the water molecules move into the cell.Exosmosis occurs as the water molecules move out from the cell.When placed in Hypotonic Solution, the cell slightly enlarges or even bursts.When placed in Hypertonic Solution, the cell shrinks in size and loses shape.(d) Difference between Turgidity and FlaccidityTurgidityFlaccidityIt is the state of a cell in which the cell wall is rigid and stretched by an increase in the volume of vacuoles due to the absorption of water.It is the condition in which the cell content is shrunken and the cell is not tight.It occurs when the cell is placed in Hypotonic solution.It occurs when the cell is placed in Hypertonic solution.It is caused by Endosmosis.It is caused by Exosmosis.Water moves into the cell.Water moves out of the cell.

Question 7

Question 3The diagram below represents a layer of epidermal cells showing a fully grown root hair. Study the diagram and answer the questions that follow:(a) Name the parts labelled A, B, C and D.(b) The root hair cell is in a turgid state. Name and explain the process that caused this state.(c) Mention one distinct difference between the parts labelled A and B.(d) Draw a diagram of the above root hair cell as it would appear when a concentrated solution of fertilizers is added near it.

Accepted Answer

(a) The parts labelled A, B, C and D are:A → Cell wallB → Cell membraneC → CytoplasmD → Nucleus(b) A root hair gets turgid because of the absorption of water from the surrounding. Absorption of water by root hair is achieved by the process of Osmosis. Root hairs contain cell sap which has a higher concentration of salts as compared to the outside soil water. This causes the water from the surrounding to move in because of endosmosis and in the process the root hair gets turgid.(c) The cell wall of a root hair is freely permeable and allows both salt and water to pass through whereas the cell membrane of a root hair is semi-permeable and does not allow large dissolved salt molecules to pass through.(d) Below is the diagram of the root hair cell as it would appear when a concentrated solution of fertilizers is added near it:

Question 8

Question 4Study the diagram given below and answer the questions that follow:(a) Name the process being studied in the above experiment.(b) Explain the process mentioned in (a) above(c) Why is oil placed over water?(d) What do we observe with regard to the level of water when this set up is placed in (1) bright sunlight (2) humid conditions (3) windy day?(e) Mention any three adaptations found in the roots of the plant which enable them to carry out the process mentioned in (a).

Accepted Answer

(a) The process of absorption of water by plant roots through osmosis is being studied here.(b) Absorption of water by the root is by means of root hairs. A root hair contains cell sap which has a higher concentration of salts as compared to the outside soil water. This difference sets of osmosis and the outside soil water diffuses into the root hair. From the cell bearing root hair, water continues to pass to adjoining cells one after another to finally enter the xylem vessels. The turgidity acquired by the cells in the process also helps to push the water upwards through the xylem vessels.(c) The surface of water is covered with oil to prevent any loss of water by evaporation.(d) Roots absorb water and hence, the level of water in set up A falls down. Since the surface of water was covered with oil, there will be no effect of factors such as bright sunlight, humid conditions and windy day on the given set up. Hence, the level of water.(d) Below are the observations with regard to the level of water for the different situations:Bright Sunlight — When this set up is placed in bright sunlight, the water level in the test tube is seen to be less when compare to its initial marking as the rate of transpiration is very high.Humid Conditions — When this set up is placed in humid conditions, the water level in the test tube decreases from its initial mark, but at a very slow rate as the rate of transpiration is reduced.Windy Day — When this set up is placed in windy day the rate of transpiration highly increases thus the level of the water in the test tube is seen to decrease fast from its initial marking.(e) Adaptations in plants to foster the process of absorption of water by plant roots:Large surface area provided by rootlets and root hairs.Root hairs contain cell sap at a higher concentration than that of the surrounding waterRoot hairs with thin walls.

Question 9

Question 5Three cylinders of potato were carefully dried on a blotting paper and weighed. Each piece weighed 3 grams. Each one was placed in the beaker as shown below:Answer the following questions:(a) After 48 hours, which potato cylinder would be the heaviest?(b) The movement of which substance is mainly responsible for the weight change in the potato cylinders?(c) Name and define the process which is responsible for the movement of substance mentioned in answer (b).(d) Write specific names of the processes which occur in beakers B and C [kinds of processes defined in answer (c)].(e) Would there be any difference in the weight of the potato cylinder in beaker A after 48 hours? Give reason.

Accepted Answer

(a) After 48 hours, Cylinder B kept in distilled water will be the heaviest as distilled water will act as a hypotonic solution for Potato Cylinder. The Potato Cylinder will absorb distilled water from the beaker through the process of endosmosis and its weight will increase.(b) Movement of water between potato cylinders and beakers is mainly responsible for the weight change in the potato cylinders.(c) The physical process which is responsible for the movement of substance mentioned in answer (b) is Osmosis. Osmosis is the movement of water molecules from their region of higher concentration to their region of lower concentration through a semi-permeable membrane.(d) The process that takes place in beaker B is osmosis, which is diffusion of water across the membrane of the potato slice cells. Plasmolysis occurs in beaker C as the potato shrinks due to hypotonic solution of 20% sucrose solution.(d) Beaker B → Endosmosis     Beaker C → Exosmosis(e) There will be no change in the weight of the potato cylinder in beaker A because it is kept in air. As there is no movement of water between potato cylinder and beaker so no significant change in the weight of the potato cylinder is observed in beaker A.

Question 10

Question 7Study the experimental setup in the figure and then answer the questions that follow.(a) What phenomenon is being studied by this setup?(b) Explain the phenomenon mentioned in (a) above.(c) What is meant by 'semipermeable membrane'?(d) What will you observe in the setup after about half an hour? Give a reason for your answer.

Accepted Answer

(a) Osmosis phenomenon is being studied by this setup.(b) Osmosis is the movement of water molecules from their region of higher concentration (dilute solution or with a lower solute concentration) to their region of lower concentration (concentrated solution or with a higher solute concentration) through a semi permeable membrane.(c) A semipermeable membrane is a membrane which allows the passage of molecules selectively. It allows a solvent such as water molecules to pass through it freely but prevents the passage of the solute (sugar or salt molecules in solution).(d) Water molecules will continue to pass from 5% sucrose solution to 10% sucrose solution through the semipermeable membrane due to osmosis. This will continue till the concentration of water molecules becomes the same in both ends of the setup.

Question 11

Question 8Given below is the figure of a plant cell showing different kinds of pressure acting upon it. Study the figure and answer the questions that follow:(a) In the figure, 1, 2 and 3 represent :Cytoplasm, Nucleus, Vacuole respectivelyVacuole, Cytoplasm, Cell wall respectively.Cytoplasm, Cell membrane and vacuole respectively.Cytoplasm, Cell wall and Vacuole respectively.(b) B in the figure represents :Osmotic pressureTurgor pressureWall pressureDiffusion pressure(c) A in the figure represents :Imbibition pressureWall pressureTurgor pressureOsmotic pressure(d) C in the figure represents :Turgor pressureOsmotic pressureWall pressureImbibition pressure(e) Draw a neat and labelled diagram of a plasmolysed plant cell.

Accepted Answer

(a) Cytoplasm, Cell wall and Vacuole respectively.(b) Wall pressure(c) Turgor pressure(d) Osmotic pressure(e) Labelled diagram of a plasmolysed plant cell is given below :

Absorption by Roots — The Process Involved

Descriptive Type

Multiple Choice Type

Short Answer Type

Structured Application Skill Type