Osmosis and Plasmolysis Questions in English

(C) When a plant cell is placed in pure water, water enters the cell due to endosmosis because the water potential of pure water is higher than that of the cell sap. As water enters, the cell becomes turgid and the pressure potential $(\Psi_p)$ increases. The process continues until the water potential $(\Psi_w)$ of the cell becomes equal to the water potential of the surrounding pure water (which is $0$). At this equilibrium, the pressure potential $(\Psi_p)$ of the cell becomes equal to its osmotic potential $(\Psi_s)$ in magnitude, resulting in a net water potential of $0$.

(C) Osmosis is the diffusion of water molecules through a differentially permeable membrane.
Endosmosis is the process where water enters the cell when it is placed in a hypotonic solution.
As water enters the cell,it exerts pressure against the cell wall,causing the cell to become turgid.

(D) If an external solution has the same osmotic pressure as the cytoplasm of a cell,it is known as an isotonic solution.
When cells are placed in an isotonic solution,the water potential inside and outside the cell is equal.
Therefore,there is no net movement of water across the cell membrane,and the cell maintains its shape.

(A) When a plant cell is placed in a saline solution (hypertonic solution),water moves out of the cell due to exosmosis.
As a result,the protoplast shrinks away from the cell wall,causing the cell to decrease in size (plasmolysis).

(A) cell swells up when kept in a hypotonic solution due to the process of endosmosis.
In a hypotonic solution,the concentration of solutes outside the cell is lower than inside the cell,causing water to move into the cell through the semi-permeable membrane.

(B) Osmosis is a special type of diffusion that occurs when water (solvent) molecules move across a semi-permeable membrane.
In this process,the solvent molecules move from a region of higher solvent concentration (or lower solute concentration) to a region of lower solvent concentration (or higher solute concentration).
Therefore,osmosis specifically refers to the movement of the solvent,not the solute.

(D) When a leaf peeling of Tradescantia is kept in a medium having $10 \% \;NaCl$ solution,the external medium becomes hypertonic compared to the cell sap.
Due to this,water moves out of the cell through the process of exosmosis.
As water leaves the cell,the protoplast shrinks and separates from the cell wall,a phenomenon known as plasmolysis.
Therefore,the observation under the microscope will show the exit of water from the cell.

(A) Plasmolysis is the phenomenon of the shrinkage of the protoplasm away from the cell wall.
This occurs due to exosmosis,which is the movement of water out of the cell.
Exosmosis happens when a cell is placed in a hypertonic solution,which has a lower water potential than the cell's internal environment.

(A) The shrinkage of the protoplast of a living cell away from its cell wall due to exosmosis under the influence of a hypertonic solution is called Plasmolysis.
When a cell is plasmolysed,it loses water and becomes flaccid.
In a flaccid cell,the turgor pressure $(TP)$ becomes zero.
Since the diffusion pressure deficit $(DPD)$ is calculated as $DPD = OP - TP$,when $TP = 0$,the $DPD$ becomes equal to the osmotic pressure $(OP)$.

(B) Osmosis is defined as the diffusion of water from its pure state or a dilute solution into a stronger solution when the two are separated by a semi-permeable membrane.
In the thistle funnel experiment,the process of osmosis stops when the hydrostatic pressure equals the osmotic pressure.
When a sugar solution is added to the beaker,the concentration of the solution in the beaker increases,making it hypertonic compared to the solution inside the thistle funnel.
As a result,water moves out of the thistle funnel into the beaker through the semi-permeable membrane,a process known as exosmosis.
Consequently,the level of the solution in the thistle funnel lowers.

(A) The water potential $(\Psi_w)$ of a cell is given by the equation $\Psi_w = \Psi_s + \Psi_p$, where $\Psi_s$ is the osmotic potential and $\Psi_p$ is the pressure potential.
In a wilted cell, the cell membrane pulls away from the cell wall (plasmolysis), resulting in a turgor pressure of zero $(\Psi_p = 0)$.
Therefore, the water potential becomes equal to the osmotic potential $(\Psi_w = \Psi_s)$.

(C) The water potential of a cell is given by the equation $\Psi_{w} = \Psi_{s} + \Psi_{p}$.
In a plasmolysed cell,the protoplast has shrunk away from the cell wall,meaning there is no turgor pressure exerted against the cell wall.
Therefore,the pressure potential $\Psi_{p}$ becomes $0$.
Substituting this into the equation,we get $\Psi_{w} = \Psi_{s} + 0$,which simplifies to $\Psi_{w} = \Psi_{s}$.

(A) $I$. Limiting plasmolysis: This is the initial stage where the osmotic concentration of the cell sap is equivalent to the external solution,and the cell wall pressure is zero.
$II$. Incipient plasmolysis: This is the stage where the protoplast begins to withdraw from the corners of the cell wall due to the initial loss of water.
$III$. Evident plasmolysis: This is the final stage where the protoplast detaches completely from the cell wall and assumes a spherical shape due to significant exosmosis.

(B) Plasmolysis occurs when a plant cell is placed in a hypertonic solution,causing water to move out of the cell via osmosis. As water leaves,the protoplast shrinks away from the cell wall. The space between the cell wall and the shrunken protoplast is filled with the external hypertonic solution that caused the plasmolysis.

(C) When a cell is placed in a solution,if the volume of the cell increases,it indicates that water has entered the cell.
This process is known as endo-osmosis.
Endo-osmosis occurs when the external solution has a higher water potential (lower solute concentration) compared to the cell cytoplasm.
Such a solution is called a $Hypotonic$ solution.

(C) When a cell is placed in a solution and there is no change in its volume,it indicates that there is no net movement of water into or out of the cell.
This condition occurs when the external solution is isotonic to the cell sap.
An isotonic solution has the same osmotic concentration as the cell sap.
Since the external sugar solution has a concentration of $0.4 \; M$,the concentration of the cell sap must also be $0.4 \; M$.

(B) When a plant cell is placed in distilled water,the water potential of the surrounding medium is higher than that of the cell sap.
As a result,water enters the cell through the process of endosmosis.
This influx of water increases the turgor pressure within the cell,causing it to swell up.
However,unlike animal cells,plant cells do not burst because the rigid cell wall provides structural support.

(C) solution whose osmotic concentration is equal to the cell sap is called an $isotonic$ solution.
In an $isotonic$ solution,the water potential of the external solution is equal to the water potential inside the cell.
Therefore,there is no net movement of water across the cell membrane,and the cell remains in its normal state.

(A) membrane that allows the passage of solvent molecules (like water) but prevents the passage of solute molecules is known as a semipermeable membrane.
It acts as a perfect partition in osmotic systems because it maintains the concentration gradient by allowing only water to move across it.

(N/A) $\Rightarrow$ Neutral solutes may move across the membrane by the process of simple diffusion along the concentration gradient,i.e.,from higher concentration to the lower. Water may also move across this membrane from higher to lower concentration. Movement of water by diffusion is called osmosis.

(N/A) When placed in a salt solution (hypertonic),water moves out of the cell due to exosmosis. As a result,the protoplasm shrinks away from the cell wall,a phenomenon known as plasmolysis.
$(b)$ When the plasmolysed cell is placed in distilled water (hypotonic),water enters the cell due to endosmosis. The protoplasm regains its original position,and the cell becomes turgid.

(N/A) $1$. During summer,the rate of transpiration is very high. If a plant is not watered for a day,the water loss through transpiration exceeds the water uptake by roots,leading to a decrease in turgor pressure.
$2$. This causes the leaves and stems to wilt (droop).
$3$. Yes,this process is reversible. If the plant is watered promptly,the cells will regain their turgor pressure,and the plant will recover its normal upright position.
$4$. However,if the water deficit persists for too long,the plant may reach a permanent wilting point,leading to leaf abscission and eventually the death of the plant.

(D) $\Rightarrow$ There are three types of solutions based on their osmotic concentration relative to the cytoplasm: Isotonic,Hypotonic,and Hypertonic solutions.
$\Rightarrow$ $1.$ Isotonic solution: When the external solution balances the osmotic pressure of the cytoplasm,it is called an isotonic solution. In this state,there is no net movement of water across the cell membrane.
$\Rightarrow$ $2.$ Hypotonic solution: If the external solution is more dilute than the cytoplasm (lower solute concentration),it is called a hypotonic solution. In this case,water moves into the cell,causing it to swell.
$\Rightarrow$ $3.$ Hypertonic solution: If the external solution is more concentrated than the cytoplasm (higher solute concentration),it is called a hypertonic solution. In this case,water moves out of the cell,causing it to shrink or undergo plasmolysis.

(N/A) $\Rightarrow$ When a cell or tissue is placed in an isotonic solution,there is no net movement of water into or out of the cell.
$\Rightarrow$ If the external solution balances the osmotic pressure of the cytoplasm,it is said to be isotonic.
$\Rightarrow$ When the flow of water into the cell and out of the cell is in equilibrium,the cells are said to be in a flaccid state.

(A) The movement of water molecules across a semi-permeable membrane from a region of higher water potential to a region of lower water potential is specifically known as $Osmosis$. While diffusion is the general movement of particles from higher to lower concentration, the specific term for water diffusion across a membrane is $Osmosis$.

(B) The thistle funnel experiment demonstrates osmosis,where water moves from a region of lower solute concentration to a region of higher solute concentration through a semi-permeable membrane.
Initially,water moves from the beaker into the thistle funnel,causing the liquid level in the funnel to rise.
If sugar is added to the beaker,the solute concentration in the beaker increases,making the solution in the beaker hypertonic compared to the solution inside the thistle funnel.
As a result,water will move out of the thistle funnel and into the beaker due to osmosis.
Therefore,the liquid level in the thistle funnel will decrease.

(D) semi-permeable membrane is a type of biological or synthetic membrane that allows certain molecules or ions to pass through it by diffusion.
$1$. The urinary bladder of a frog acts as a natural semi-permeable membrane.
$2$. Parchment paper is a classic laboratory example of a semi-permeable membrane used in osmosis experiments.
$3$. The egg membrane (the thin membrane found just inside the shell) of a hen is also a well-known biological semi-permeable membrane.
Therefore,all the given options act as semi-permeable membranes.

(A) Plasmolysis occurs when a plant cell is placed in a hypertonic solution.
Water moves out of the cell due to osmosis,causing the protoplast to shrink away from the cell wall.
The space between the rigid cell wall and the shrunken plasma membrane is filled with the external hypertonic solution that caused the water loss.

(C) In the given figure:
$P$ represents a Plasmolysed cell,where water has moved out of the cell,causing the protoplast to shrink away from the cell wall.
$Q$ represents a Flaccid cell,where the water potential inside and outside the cell is equal,resulting in no net movement of water.
$R$ represents a Turgid cell,where water has moved into the cell,causing the protoplast to press against the cell wall.
Therefore,the correct sequence is Plasmolysed cell,Flaccid cell,Turgid cell.

(B) $1$. $A$ solution that is less concentrated than the cytoplasm is known as a Hypotonic solution $(P)$.
$2$. $A$ solution that is more concentrated than the cytoplasm is known as a Hypertonic solution $(Q)$.
$3$. $A$ solution that has the same osmotic pressure as the cytoplasm is known as an Isotonic solution $(R)$.
Therefore,the correct sequence is $P$: Hypotonic,$Q$: Hypertonic,$R$: Isotonic.

(A) Plasmolysis is the process in which the protoplast of a plant cell shrinks away from the cell wall due to the loss of water.
This occurs when the cell is placed in a hypertonic solution,which has a higher solute concentration than the cytoplasm of the cell.
Due to the osmotic gradient,water moves out of the cell,causing the protoplast to shrink.
Therefore,the correct option is $A$.

(D) Osmosis is a special type of diffusion of water across a semi-permeable membrane.
It is a passive process,meaning it does not require the expenditure of metabolic energy $(ATP)$.
It occurs from a region of higher water potential to a region of lower water potential.
Therefore,all the given statements are correct characteristics of osmosis.

(C) Water is absorbed by the root hairs primarily through the process of $Diffusion$ (specifically $Osmosis$).
$Osmosis$ is the movement of water molecules from a region of higher water potential to a region of lower water potential through a semi-permeable membrane.
While minerals may be absorbed via $Active$ $transport$, the bulk movement of water into the roots occurs passively along a water potential gradient.

(B) In areas with high salt concentrations,the soil solution becomes hypertonic relative to the plant cell sap.
Due to the hypertonic nature of the soil,water moves out of the plant root cells into the soil through the process of exosmosis.
This loss of water leads to plasmolysis and dehydration of the root cells,which prevents the plant from absorbing water and nutrients,ultimately inhibiting growth.

(B) The diagram shows a plasmolyzed cell,which occurs when a plant cell is placed in a hypertonic solution (a solution with a higher solute concentration than the cell sap).
In a hypertonic solution,water moves out of the cell due to exosmosis,causing the protoplasm to shrink away from the cell wall.
As the cell loses water,its turgor pressure decreases and its osmotic pressure increases.
Therefore,statement $B$ is incorrect because the cell was placed in a hypertonic solution,not a hypotonic one.