A. EXPERIMENTS TO BE PERFORME
1. Study of osmosis by potato osmoscope.
Aim :- To study the process of osmosis using potato osmoscope.
Requirements :- A fresh Potato, peeler or scalpel, petri dishes/ bowls/trough/shallow glass beakers, pins, concentrated sugar solution, coloured water, etc.
Principle :- When two solutions of different concentrations are separated by semipermeable membrane, the flow of solvent is from the region of weaker solution (having low solute concentration) to the region of stronger solution (having high solute concentration) till the equilibrium is reached so that the osmotic pressure are balance.
Osmosis is of two types viz. endosmosis and exosmosis.
Figure :-
Procedure :- 1. Take a fish potato tuber and peel off the skin with the help of scalpel.
2. Cut the potato from one side in such a way that it will make a flat base.
3. Scoop the peeled tuber properly so as to make a hollow block (well) in potato with thin intact base bottom and care should be taken that it will not rupture at base.
4. Now add concentrated sugar solution in that cavity and mark its level by inserting a pin in the cavity wall.
5. Place this potato osmoscope in a petri dish/bowl or glass beaker, filled with coloured water.
6. Mark the initial level within pin. After sometime mark the level of sugar solution in the potato osmoscope.
Observations :- 1. You can easily note that level of sugar solution in the potato osmoscope, rises after sometime. The solution in the cavity osmoscope also becomes coloured.
2. It can be inferred that coloured water from the petri dish/bowl has entered the cavity of the potato osmoscope.
Inferences :- 1. The rise in the sugar solution is due to osmosis.
2. The membranes of the living cells of potato tuber functions as semipermeable membrane.
3. Water from outside (hypotonic) enters the cavity filled with concentrated sugar solution (hypotonic) thus demonstrating osmosis.
Questions
1. Potato is used to prepare an osmoscope - justify.
Ans :- Peeled potato represents a living system to demonstrate the process of osmosis. The cell membranes of potato act as the semipermeable membranes and allow the passage of water from hypotonic solution to hypertonic solution.
2. Define Permeability.
Ans :- Permeability is defined as the property of membranes to allow passive diffusion of molecules.
3. Define osmotic pressure.
Ans :- Osmotic pressure is equivalent to the pressure which must be exerted upon the solution to prevent the flow of solvent across a semipermeable membrane.
4. Do you find any role of osmosis in water purification?
Ans :- In water purification reverse osmosis is used. it is the reverse movement of water through a semi permeable membrane from a more concentrated solution to a more dilute solution by applying external pressure on the more concentrated solution. it is used for removing salt from saline water.
5. Osmosis plays important role in stomatal movement, explain.
Ans :- Stomatal movement depends on the turgidity of guard cells. Guard cells become turgid due to endosmosis and the stoma opens. Guard cells become flaccid due to exosmosis and the stoma closes.
Multiple Choice Questions
1. In living cells, an osmosis specially refers to the movement...
a. diffusion of solvent
b. diffusion of solute
c. diffusion of water
d. diffusion of solute and solvent both
Ans :- c. diffusion of water
2. The direction and rate of osmosis is controlled by...
a. Nature of property of membrane
b. Nature of solvent
c. Pressure gradient and concentration gradient
d. Cell structure and composition of cytoplasm
Ans :- c. Pressure gradient and concentration gradient
3. The structure that contributes to the solute potential of a cell is...
a. Vacuolar sap
b. Cell sap
c. Water
d. Solute particles
Ans :- d. Solute particles
4. Osmotic potential refers to...
a. Movement of water molecules from hypotonic solution to hypertonic solution
b. Movement of water molecules from hypertonic solution to hypotonic solution
c. Pressure potential
d. Moment of water molecules from hypotonic solution to isotonic solution
Ans :- a. Movement of water molecules from hypotonic solution to hypertonic solution
5. Which of the following is not semipermeable?
a. Parchment paper
b. Egg membrane
c. Bladder membrane
d. Cell wall
Ans :- d. Cell wall
6. Which acid is used to extract egg membrane?
a. Acetic acid
b. Dilute HCL
c. Concentrated HCL
d. Dilute \(H_{2}SO_{4}\)
Ans :- a. Acetic acid
*PDF Link - Click Me :) or Click on Download Button Below:
*Click on 'Next' to view remaining Questions Answer or 'Previous' to main post!
