Study Of Plasmolysis In Epidermal Peels: Diagram, Overview

Edited By Irshad Anwar | Updated on Jul 02, 2025 06:53 PM IST

Plasmolysis

Plasmolysis is the process whereby, because of a loss of water in a hypertonic solution, the plant cell contracts towards the centre away from the cell wall. This has been caused by osmotic pressure and may result in a heavy loss of water from the cell, whereby causes a shrink of the cell, and consequently, the cell may die. Two types of plasmolysis can be divided as follows:

Concave Plasmolysis: This is a reversible form where the plasmalemma can return to its original state if it is reintroduced to a hypotonic solution.
Convex Plasmolysis: It is an irreversible form where the plasmalemma can't come back. Thus permanent damage of the cell membrane in this process leads to its death.

Aim

The experiment will try to observe plasmolysis in Rhoeo plant leaves epidermal peels with the help of hypertonic and hypotonic solutions. This shall help in understanding how plant cells react to osmotic changes in their environment.

What Is Plasmolysis?

Plasmolysis refers to the process whereby the protoplasm of a plant cell shrinks due to loss of water when put in a hypertonic solution. This is because of a loss of water from the cell towards equilibrating the concentration of solutes, thus leading to a contraction of the cell membrane away from the cell wall.

Why Use Rhoeo Leaves?

Rhoeo leaves will be used because their coloured cell sap will show changes more clearly under the microscope.

How Water Passes Through the Cell Membrane

The cell membrane shows selective movement; water molecules and ions may or may not easily pass while some are blocked. This selective permeability of the cell membrane allows water to enter the cell or leave it for proper cellular activity.

Materials Required

Needle
Forceps
Droppers
Glass slides
Watch glass
Rhoeo leaves
Coverslips
Compound microscope
Sodium chloride 5% solution
Sodium chloride 0.1% solution

Procedure

Take two clean and dry glass slides on a table.
Take fresh leaves of Rhoeo and put it on a watch glass
Fold the leaves from top to bottom and tear them from the lower side or with the help of a clean blade.
With the forceps, take two small pieces of epidermis from the lower surface of the Rhoeo leaf.
Place the epidermal peels on a glass slide.
Place 12 drops of a 0.1% solution of sodium chloride on one slide.
Add 12 drops of a 5% solution of sodium chloride to the other slide.
Then, with the help of a needle, cover the slides with a coverslip.
Keep the slides undisturbed for some minutes.
Observe under a compound microscope the slides and note changes.

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Observation

After 30 minutes, cells in the sodium chloride 0.1% solution appear turgid, while in the sodium chloride 5% solution, they show shrinkage and plasmolysis.
The cells of the hypertonic solution lose huge amounts of water with a detachment of the membrane from the cell wall.

Precautions

Epidermal peels are taken from the lower surface of Rhoeo leaves.
The peels should be fresh and not dry.
The slide is to be prepared in such a manner that no air bubbles should appear below the coverslips.

Conclusion

When plant cells are put in a concentrated salt solution, plasmolysis will take place. It comprises shrinking away of the protoplasm detaching the cell membrane from the cell wall because of loss of water. Contrary to a dilute solution, 0.1 % sodium chloride, the cells will be turgid as the water will move into the cell to equilibrate the osmotic pressure of the cell.

Frequently Asked Questions (FAQs)

1. What is Plasmolysis?

Plasmolysis is the process whereby the protoplasm of a plant cell shrinks away from the cell wall due to loss of water by being placed in a hypertonic solution.

2. What is Plasmolysis?

Plasmolysis is the process in which plant cells lose water to a hypertonic solution, causing the cell membrane to shrink away from the cell wall. This occurs when the concentration of solutes outside the cell is higher than inside, leading to water moving out of the cell through osmosis.

3. What is Incipient Plasmolysis?

The incipient plasmolysis is a stage at which the protoplasm is just beginning to withdraw from the cell wall.

4. Name any two importance of Plasmolysis.

It determines or investigates the nature of the living cells.
The process is applied in food preservation through pickling and salting to halt the growth of bacteria.

5. What is Osmotic Pressure?

The pressure which, if applied, will just prevent the passage of a solvent through a semipermeable membrane by osmosis.

6. What is Turgor Pressure?

Turgor pressure is the hydrostatic pressure exerted by the fluid inside the cell against the cell wall due to its influx into the cell through the endosmosis process.

7. What is the importance of studying plasmolysis in plant physiology?

Studying plasmolysis helps scientists understand:

8. What is the role of osmolytes during plasmolysis and recovery?

Osmolytes are compatible solutes that plants accumulate to help maintain osmotic balance. During plasmolysis, existing osmolytes help slow water loss. In recovery (deplasmolysis), plants may produce more osmolytes to help draw water back into the cell without interfering with cellular functions.

9. How does osmotic pressure relate to plasmolysis?

Osmotic pressure is the force that drives water movement during plasmolysis. When the osmotic pressure of the external solution is higher than that of the cell contents, water moves out of the cell, leading to plasmolysis. The greater the difference in osmotic pressure, the more severe the plasmolysis.

10. How do plant cells prevent excessive plasmolysis in nature?

Plant cells have several mechanisms to prevent excessive plasmolysis:

11. What is the role of aquaporins in plasmolysis?

Aquaporins are water channel proteins in the cell membrane that facilitate rapid water movement. During plasmolysis, aquaporins can increase the rate of water loss from the cell. Some plants can regulate aquaporin activity to help control water loss during osmotic stress.

12. How does plasmolysis affect the movement of substances across the cell membrane?

Plasmolysis can affect membrane transport in several ways:

13. How does temperature affect the rate of plasmolysis?

Higher temperatures generally increase the rate of plasmolysis. This is because temperature affects the kinetic energy of water molecules, making them move faster. As a result, water can move out of the cell more quickly at higher temperatures, accelerating the plasmolysis process.

14. Can plasmolysis be used to study symplastic transport in plants?

Yes, plasmolysis can be used to study symplastic transport. By observing how plasmolysis affects the movement of fluorescent dyes or other tracers between cells, researchers can gain insights into the function of plasmodesmata and the continuity of the symplast under osmotic stress.

15. Can plasmolysis be reversed?

Yes, plasmolysis can be reversed through a process called deplasmolysis. When the plasmolyzed cell is placed back into a hypotonic or isotonic solution, water will move back into the cell, causing the cell membrane to expand and return to its original position against the cell wall.

16. How does turgor pressure change during plasmolysis?

Turgor pressure, which is the force exerted by water pushing the cell membrane against the cell wall, decreases during plasmolysis. As water leaves the cell, the pressure drops, eventually reaching zero when full plasmolysis occurs.

17. How does the concentration of the external solution affect the rate of plasmolysis?

The higher the concentration of the external solution (more hypertonic), the faster the rate of plasmolysis. This is because a greater concentration gradient leads to more rapid water loss from the cell.

18. Why are epidermal peels used to study plasmolysis?

Epidermal peels are used because they consist of a single layer of cells, making it easier to observe changes under a microscope. The transparency of these cells allows for clear visualization of the plasmolysis process without interference from other cell layers.

19. What is the role of the cell wall during plasmolysis?

The cell wall remains rigid and maintains the overall shape of the plant cell during plasmolysis. It acts as a barrier, preventing the cell from bursting even when the cell membrane shrinks away from it due to water loss.

20. What is the difference between plasmolysis and wilting?

Plasmolysis occurs at the cellular level when individual cells lose water to a hypertonic environment. Wilting is a whole-plant response to water loss, where the plant becomes limp due to a lack of turgor pressure in many cells. Wilting can occur without plasmolysis, such as when a plant loses water faster than it can be replaced.

21. How does plasmolysis affect the concentration of solutes within the cell?

As water leaves the cell during plasmolysis, the concentration of solutes within the remaining cellular fluid increases. This is because the same amount of solutes is now dissolved in a smaller volume of water, effectively concentrating the cell's contents.

22. Can plasmolysis occur in all plant cell types?

While all plant cells can potentially undergo plasmolysis, some cell types are more susceptible than others. Cells with thin walls, like those in leaves and young tissues, are more likely to show visible plasmolysis than cells with thick walls, like those in woody tissues.

23. How does the shape of a plant cell change during plasmolysis?

During plasmolysis, the cell membrane pulls away from the cell wall, causing the protoplast (cell contents) to shrink and round up. The overall shape of the cell (defined by the cell wall) remains the same, but the living part of the cell becomes smaller and more spherical within the cell wall.

24. What is the difference between plasmolysis and dehydration?

While both involve water loss, plasmolysis specifically refers to the separation of the cell membrane from the cell wall due to osmotic water loss in a hypertonic solution. Dehydration is a more general term for water loss that can occur through various mechanisms, not necessarily involving osmosis or cell membrane shrinkage.

25. How does the speed of plasmolysis induction affect cell survival?

The speed of plasmolysis induction can significantly impact cell survival:

26. How does plasmolysis affect the overall health of a plant?

Prolonged or severe plasmolysis can be detrimental to plant health. It can lead to wilting, reduced growth, and even cell death if the water loss is not reversed. However, mild, temporary plasmolysis is a normal response to osmotic stress and doesn't typically cause lasting harm.

27. What is the relationship between plasmolysis and programmed cell death in plants?

Severe or prolonged plasmolysis can trigger programmed cell death (PCD) in plants. This is part of the plant's stress response mechanism. Mild, reversible plasmolysis usually doesn't lead to PCD, but if the osmotic stress is too severe or prolonged, it can activate PCD pathways as a way to sacrifice some cells for the overall survival of the plant.

28. Can plasmolysis be used to estimate the osmotic potential of a cell?

Yes, plasmolysis can be used to estimate a cell's osmotic potential. By exposing cells to solutions of known concentrations and observing at which concentration plasmolysis begins (incipient plasmolysis), researchers can approximate the osmotic potential of the cell's contents.

29. Can plasmolysis be used to study cell wall elasticity?

Yes, plasmolysis can provide insights into cell wall elasticity. By observing how quickly and to what extent cells recover from plasmolysis (deplasmolysis), researchers can infer information about the elasticity and mechanical properties of the cell wall.

30. Can plasmolysis be used to study the effects of cryopreservation on plant cells?

Yes, studying plasmolysis can provide insights into cryopreservation effects. The ability of cells to undergo and recover from plasmolysis can indicate their membrane integrity and overall viability after freezing and thawing, which is crucial for successful cryopreservation of plant tissues.

31. Can plasmolysis be used to study membrane permeability?

Yes, plasmolysis can be used to study membrane permeability. By observing the rate of plasmolysis in different solutions, researchers can gain insights into how readily certain substances cross the cell membrane. This technique can help in understanding selective permeability and the function of membrane transport proteins.

32. How does the cytoskeleton respond during plasmolysis?

The cytoskeleton plays a crucial role during plasmolysis:

33. How does plasmolysis differ from cytolysis?

Plasmolysis occurs in plant cells when they lose water to a hypertonic solution, causing the cell membrane to shrink away from the cell wall. Cytolysis, on the other hand, happens in animal cells when they take in too much water in a hypotonic solution, causing the cell to burst.

34. What is the difference between incipient plasmolysis and full plasmolysis?

Incipient plasmolysis is the initial stage where the cell membrane just begins to pull away from the cell wall at the corners. Full plasmolysis occurs when the cell membrane has completely separated from the cell wall, forming a rounded shape within the cell.

35. Why doesn't plasmolysis occur in animal cells?

Animal cells lack a rigid cell wall, so when placed in a hypertonic solution, they simply shrink overall rather than having the cell membrane pull away from a fixed structure. This process in animal cells is called crenation.

36. What types of solutions can cause plasmolysis?

Any hypertonic solution can cause plasmolysis. Common examples include concentrated sugar solutions, salt solutions, or solutions with a higher concentration of solutes than the cell's cytoplasm.

37. Can plasmolysis occur in bacterial cells?

While bacteria have cell walls, they don't undergo plasmolysis in the same way as plant cells. When exposed to hypertonic solutions, bacteria may experience a phenomenon called plasmoptysis, where the cell membrane retracts from the cell wall, but it's less visible and occurs differently due to their small size and different cell structure.

38. How does the cell wall composition affect plasmolysis?

The composition and structure of the cell wall can influence plasmolysis:

39. How does plasmolysis affect chloroplasts in plant cells?

During plasmolysis, chloroplasts, along with other organelles, are compressed as the cell volume decreases. This compression can potentially affect their function by altering their orientation or disrupting their internal structure. In severe cases, it might temporarily reduce photosynthetic efficiency.

40. What is the relationship between plasmolysis and osmotic adjustment in plants?

Osmotic adjustment is a plant's ability to accumulate solutes in response to water stress, helping to maintain turgor pressure. While plasmolysis is an immediate response to hyperosmotic conditions, osmotic adjustment is a longer-term adaptive strategy that can help plants resist or recover from plasmolysis more effectively.

41. How does the presence of pits in the cell wall affect the plasmolysis pattern?

Pits, which are thin areas in the cell wall, can affect the pattern of plasmolysis. The cell membrane may remain attached to the cell wall at these points longer than in other areas, creating a characteristic appearance during plasmolysis. This can result in a more complex plasmolysis pattern compared to cells with uniform walls.

42. What is the significance of Hechtian strands during plasmolysis?

Hechtian strands are thin cytoplasmic connections that remain between the cell membrane and cell wall during plasmolysis. They are important because they maintain contact between the plasma membrane and cell wall, facilitating the cell's ability to regain its normal shape during deplasmolysis.

43. How does the presence of a vacuole affect plasmolysis in plant cells?

The large central vacuole in mature plant cells plays a significant role in plasmolysis. As water leaves the cell, the vacuole shrinks first, causing the cytoplasm and organelles to be compressed between the shrinking vacuole and the cell wall. This often results in a characteristic concave plasmolyzed shape.

44. What is cyclosis, and how is it affected by plasmolysis?

Cyclosis, or cytoplasmic streaming, is the movement of cytoplasm within a cell. During plasmolysis, cyclosis may slow down or stop as the cell loses water and the cytoplasm becomes more concentrated. This can affect cellular processes that depend on cytoplasmic movement.

45. How does plasmolysis differ in young versus mature plant cells?

Young plant cells typically have smaller vacuoles and more cytoplasm, so plasmolysis may appear more uniform throughout the cell. Mature cells with large central vacuoles often show more dramatic plasmolysis, with the cytoplasm and organelles being compressed against the cell wall as the vacuole shrinks.

46. What role does the endoplasmic reticulum play during plasmolysis?

The endoplasmic reticulum (ER) helps maintain cellular structure during plasmolysis. It can form connections between the cell membrane and other organelles, helping to organize the cell's contents as the volume decreases. The ER may also be involved in signaling pathways that respond to osmotic stress.

47. How does plasmolysis affect plasmodesmata?

Plasmolysis can disrupt plasmodesmata, the channels that connect adjacent plant cells. As the cell membrane pulls away from the cell wall, these connections may be stretched or broken. This can temporarily interrupt cell-to-cell communication and transport through the symplast.

48. What is the difference between positive and negative turgor pressure, and how do they relate to plasmolysis?

Positive turgor pressure occurs when the cell is fully hydrated and the cell membrane pushes against the cell wall. Negative turgor pressure occurs during plasmolysis when the cell loses water and the membrane pulls away from the wall. Plasmolysis always involves a shift from positive to zero or negative turgor pressure.

49. How does plasmolysis affect the Casparian strip in root endodermis cells?

The Casparian strip, a band of impermeable material in the cell walls of endodermis cells, is not directly affected by plasmolysis. However, severe plasmolysis in these cells could potentially disrupt the tight connection between the plasma membrane and the Casparian strip, temporarily affecting its function in controlling water and solute movement in roots.

50. How does plasmolysis affect the Donnan equilibrium in plant cells?

The Donnan equilibrium, which describes the distribution of ions across a semi-permeable membrane, can be disrupted during plasmolysis. As water leaves the cell and solute concentrations change, the balance of ions between the cell and its environment may shift, potentially affecting cellular processes and recovery.

51. How does plasmolysis affect the function of tonoplast in plant cells?

The tonoplast, or vacuolar membrane, plays a crucial role during plasmolysis:

52. How does the presence of a mucilage layer affect plasmolysis in certain plant cells?

Some plant cells, particularly in seed coats or root tips, have a mucilage layer outside the cell wall. This layer can affect plasmolysis by: