When a cell membrane is said to be selectively permeable, it means that the cell membrane controls what substances pass in and out through the membrane. This characteristic of cell membranes plays a great role in passive transport. Passive transport is the movement of substances across the cell membrane without any input of energy by the cell.
An isotonic solution has the same concentration of solutes as the cytoplasm. A measure of the tendency of water to move from one place to another. A dilute solution has more water molecules per unit volume than a concentrated solution, so it has a higher water potential than a concentrated solution.
It should be noted that the cell wall of plant cells is permeable and allows most substances to pass through. A plant cell behaves differently from an animal cell when placed in solutions with differing water potentials.
This difference is due to the presence of a cell wall in plant cells. When a plant cell is placed in a solution of higher water potential, the cell sap has Rate of osmosis concentration lower water potential than that of the solution outside the living cell.
By osmosis, water enters the cell through the partially permeable cell surface membrane. As water enters the cell, the vacuole increases in size and pushes the protoplasm against the cell wall.
The cell does not burst because it is protected by the inelastic cell wall. The turgidity of the cell with water is called turgor. An animal cell will swell and may even burst in a solution of higher water potential than the cytoplasm.
This is because unlike plant cells, animal cells do not have a cell wall to protect it. Turgor plays an important role in maintaining the shape of soft tissues in plants. Most leaves and young stems, especially those of herbaceous and non-woody plants, are able to remain firm and erect because of the turgor pressure within their cells.
When there is a high rate of evaporation of water from the cells, they lose their turgidity and the plant wilts. When a plant cell is immersed in a solution with lower water potential, the water potential of its cell sap is higher than that of the solution outside the cell.
By osmosis, water from the vacuole and cytoplasm leave the cell through the partially permeable cell surface membrane. As the cell loses water, the vacuole decreases in size.
The cytoplasm shrinks away from the cell wall. The cell is said to be plamolysed. A plasmolysed cell can be restored to its original state by placing it in water or in a solution with higher water potential.
Placing an animal cell in a solution of low water potential will cause it to lose water. An animal cell will become dehydrated and eventually die when placed in a solution of lower water potential. Plasmolysis causes tissues to become limp or flaccid.
Cells will be killed if they remain plasmolysed for too long. Soil solution is a thin film of water that surrounds individual soil particles. It usually contains dissolved mineral salts or ions. Diffusion is the net movement of molecules moving from a region of higher concentration to a region of lower concentration.
It is one of the transport phenomena that occur in nature, and it results in mixing or mass transport without requiring bulk motion. When will this process stop? When there is no concentration gradient. The concentration of substances is equal inside and outside.
It's called dynamic equilibrium. Do molecules even stop moving? There they reach their minimum motion. When diffusion stops, the concentration of molecules are in equilibrium, but they are still moving.
An equilibrium is said to be "dynamic". The reactions going in each direction still take place, they just take place at the same rate, so that the relative amounts of reactants and products do not change.Net osmosis always results in a net movement of water molecules from a region of high water concentration to a region of low water concentration.
The concentration of. Yes. The rate of osmosis is determined by several factors, including heat, molecule size, and concentration gradient.
The concentration gradient is . High concentration gradient Fast rate of diffusion Low concentration gradient Slow rate of diffusion. 8 Osmosis • Osmosis is the diffusion of free water • For the phenomenon of osmosis.
Osmosis 2 OSMOSIS INTRODUCTION: By definition, osmosis is the diffusion, or dispersion, of water through a selectively permeable membrane from a higher concentration to a lower concentration (Campbell, pg). Dec 24, · Both simple diffusion and osmosis involve the movement of a substance from an area of its higher concentration to one of lower concentration - down the concentration gradient.
Certain molecules, for example glucose, and ions move through the membrane by a passive transport process called facilitated diffusion. Osmosis is the diffusion of water across a membrane, moving to the side that has lower water concentration. BIO. —Sp’03 Diffusion, Osmosis, & Enzymes pg. 2 of 8 pgs.