Homepage Show Accessibility links
BBC Account Notifications
More menu Search Bitesize Search Bitesize
BITESIZE
National 5 Transport across membranesAll cells are enclosed by a cell membrane, which is selectively permeable. Molecules can move into or out of cells by diffusion and active transport. Cells can gain or lose water by osmosis. Part of Biology Cell biology video Videoquiz Test
OsmosisCells can gain or lose water by the process of osmosis. This depends on the water concentration of the solution inside the cell compared to water concentration of the solution outside the cell. The water concentration can be thought of as the proportion of a solution that is water. Solutions with a high concentration of solute molecules, such as sugars or salts, have a low concentration of water molecules and vice versa. Definition of osmosisThe net movement of water from a region of high water concentration to a region of low water concentration through a selectively permeable membrane. This means osmosis is a special case of diffusion: the diffusion of water. In the diagram above solution two gains water faster than it loses sugar. This is because the selectively permeable membrane lets water molecules pass through much more rapidly than it lets sugar molecules pass through. Osmosis
National 5 Subjects
What is the diffusion of water across a permeable membrane?1.2 Osmosis
Osmosis is a special type of diffusion, namely the diffusion of water across a semipermeable membrane. Water readily crosses a membrane down its potential gradient from high to low potential (Fig. 19.3) [4].
What is the diffusion of water molecules only through a membrane?Osmosis is a type of simple diffusion in which water molecules diffuse through a selectively permeable membrane from areas of high water concentration to areas of lower water concentration.
What requires a permeable membrane?A permeable membrane allows all substances like solutes and solvents to pass through it. Osmosis can occur through semi-permeable membrane that allows only water molecules to pass through it not solute particles. Thus only diffusion require permeable membrane.
How is osmosis a special case of diffusion?Yes, osmosis is a special type of diffusion because in both cases there is a movement of particles from a higher concentration region to a lower concentration region. In the process of osmosis, particle movement takes place from the region of higher concentration to lower concentration via the semi-permeable membrane.
|
Is a special case of diffusion where only water molecules move. it requires a permeable membrane.
zusammenhängende Posts
Urheberrechte © © 2024 de.apacode Inc.
