What Is Turgor Pressure Its Mechanism and Role in Plant Rigidity
In plants, turgor is also known as hydrostatic pressure or water potential or turgor pressure. Hydrostatic pressure is the force within the cell that pushes the plasma membrane against the cell wall. It is a kind of pressure which is produced due to water. It occurs only in a plant cell.
When water moves inside the cell, then it develops a pressure inside the cell wall, that pressure is especially called turgor pressure. The role of turgor pressure is to push the cell wall outward by pushing water inside the cell wall outward so that the cell wall exists in its proper shape.
How do the Plants maintain their Turgor Pressure?
Inside the plant cell, there is a vacuole organelle which is also called anima vacuole, which is in between cell membranes. Water is stored in the vacuole which pushes against the cell wall which produces pressure in the cell membrane; that pressure is called turgor pressure. Without turgor pressure, the plant will wilt.
It is also called hydrostatic pressure because plants need fluid to maintain pressure caused by pushing against the cell wall.
Role of Large Vacuoles in Plants
The vacuole is generally present in a plant cell only, which is almost filled with water. Vacuoles are majorly responsible for maintaining the turgor pressure within the cell. It also helps in removing the harmful waste products from the cell. Vacuoles contain small molecules which manage the acidic internal pH. Vacuoles are bounded by a single membrane, and this vacuole works as a combination of works, especially keeping the cell in shape.
Mechanism
A. Flaccid Cell:
The flaccid cell is also known as a shrink cell. The Turgor pressure of the flaccid cell is zero. As we know that, DPD (diffusion pressure deficit) is equal to osmotic pressure subtraction of turgor pressure.
DPD (diffusion pressure deficit) = OP(osmotic pressure) - TP (turgor pressure)
When the value of turgor pressure in a shrink cell is zero, it means the value of DPD is equal to osmotic pressure. So, it is important that the value of the flaccid cell is equivalent to the osmotic cell.
B. Turgid Cell:
In a turgid cell, turgor pressure is equivalent to the osmotic cell, then the DPD value of the turgid cell becomes zero.
In animal cells, the turgor pressure process is not found in animal cells because there are only plasma membranes present in animal cells with no cell wall. If there is too much pressure occupied by the inner content of the cell, it may be possible that the cell gets burst. So that's why turgor pressure is not found in animal cells.
Significance of Turgor Pressure
Let’s develop two cell systems that represent the plant cell, system A or system B.
In system A, cells are tightly intact with each other with zero space like brick walls, while another system B cells are loosely packed with space.
If we consider the turgor pressure of this system A cells, the water concentration of this cell has more than system B which has high turgor pressure in the cell.
Cells of system B are comparatively flaccid, which means the turgor pressure of these cells is low.
High turgor pressure in plant cells leads to proper shape which means the body of the plant will be in a good position, whereas low turgor pressure will make cells shrink toward inwards (cell wall is silently flexible) which make voids between the cells which is known as intracellular space.
When intracellular space is developed, the plant cell will wilt which results in the plant to grow wilted. That is why plants need proper amounts of water to grow healthily. Thus, this is the importance of turgor pressure. Turgor pressure is caused by the osmotic flow of water and occurs in plants, fungi and bacteria.
Wall Pressure
Wall pressure is totally opposite to the turgor pressure. It means pressure on the content of the cell wall. It works opposite the cell wall.
FAQs on Turgor in Plant Cells and Turgor Pressure Explained
1. What is turgor in plant cells?
Turgor is the pressure exerted by the cell contents against the cell wall due to water entering the cell by osmosis. When water moves into a plant cell, the vacuole swells and pushes the cytoplasm outward, creating internal pressure. This pressure keeps plant cells firm and helps maintain the shape and rigidity of non-woody plant tissues.
2. What is turgor pressure?
Turgor pressure is the outward pressure of the cell’s contents against the cell wall caused by water entering through osmosis. It is generated when:
- Water moves into the cell from a hypotonic solution
- The central vacuole expands
- The rigid cell wall resists expansion
This pressure prevents the cell from bursting and provides structural support to plants.
3. How does turgor pressure help plants?
Turgor pressure helps plants remain upright and structurally stable. It supports plants by:
- Keeping stems and leaves firm
- Maintaining cell rigidity
- Driving cell enlargement during growth
- Controlling opening and closing of stomata
Without adequate turgor, plants wilt and lose structural strength.
4. What causes loss of turgor in plant cells?
Loss of turgor occurs when water leaves the cell due to a hypertonic environment or water deficiency. This happens when:
- The surrounding solution is hypertonic
- The plant experiences drought
- Transpiration exceeds water absorption
As water exits, the vacuole shrinks and the cell becomes flaccid, leading to wilting.
5. What is the difference between turgid and flaccid cells?
Turgid cells are firm and swollen with water, while flaccid cells have lost water and become limp. The key differences include:
- Turgid cell: High turgor pressure, vacuole full, cell wall stretched
- Flaccid cell: Low turgor pressure, vacuole reduced, cell soft
Turgidity is essential for maintaining plant rigidity, whereas flaccidity leads to drooping.
6. How is turgor related to osmosis?
Turgor is directly caused by osmosis, the movement of water across a selectively permeable membrane from high to low water potential. The process occurs as follows:
- Water enters the plant cell from a hypotonic solution
- The vacuole expands
- The cytoplasm presses against the cell wall
Thus, osmosis generates the internal pressure known as turgor pressure.
7. What happens during plasmolysis and how is it related to turgor?
Plasmolysis occurs when a plant cell loses water and the plasma membrane pulls away from the cell wall due to loss of turgor pressure. It happens when:
- The cell is placed in a hypertonic solution
- Water exits by osmosis
- The vacuole shrinks significantly
Plasmolysis is an extreme loss of turgor and can damage plant cells if prolonged.
8. Why don’t animal cells have turgor pressure like plant cells?
Animal cells do not develop turgor pressure because they lack a rigid cell wall. In plant cells:
- The cell wall resists expansion
- Internal pressure builds safely
In contrast, animal cells only have a plasma membrane, so excessive water intake may cause the cell to burst instead of building stable internal pressure.
9. How does turgor pressure control the opening and closing of stomata?
Turgor pressure in guard cells regulates the opening and closing of stomata. The mechanism works as follows:
- Water enters guard cells → they become turgid → stomata open
- Water leaves guard cells → they become flaccid → stomata close
This process controls gas exchange and transpiration in plants.
10. What is the importance of turgor pressure in plant growth?
Turgor pressure is essential for plant growth because it drives cell expansion. During growth:
- Water enters young cells
- The vacuole enlarges
- The cell wall stretches under pressure
This expansion increases cell size, contributing to overall plant growth and development.
