Refers to the cell membrane controlling what substances enter and leave the cell. Controlled by proteins embedded in the cell membrane.
What in the cell membrane controls selective permeability?
Proteins embedded in the cell membrane.
What is the term diffusion?
Diffusion: the movement of particles from a region of high concentration to a region of low concentration.
What is an example of diffusion?
Oxygen and carbon dioxide diffuse across the alveolus membranes from regions of relatively high concentration to regions of relatively low concentration.
In what 3 circumstances is diffusion faster?
Diffusion is faster when:
the temperature is higher
the distance is shorter
the medium is a gas.
What is the term osmosis?
Osmosis: the movement of water molecules from a region of high water concentration to a region of low water concentration across a semi-permeable membrane.
What is an example of osmosis?
Water is continuously moving across the membrane of an Amoeba by osmosis from freshwater (high water concentration) to the interior of the cell (low water concentration).
What is a simple plant example of osmosis?
Plant root absorbs water by osmosis.
What is the application of osmosis?
Osmosis is used by the food industry for preservation of food.
What is an example of the application of osmosis?
In the food industry, tinned fruit/ vegetables are placed in a concentrated sugar (syrup) or salt solution to preserve food.
Give an explanation of the application of osmosis?
By placing fruit/veg in sugar concentrations / salt solutions - this causes any bacteria or fungi present to die due to water leaving the cells. Bacterial/Fungal cells have a higher water concentration than the syrup/salt solution.
What is the term turgor?
Turgor: the pressure exerted by the cells contents on the cell wall of a plant cell.
What is the term turgid?
Turgid: the pressure of the water forcing the cell membrane against the cell wall.
What is term plasmolysis?
Plasmolysis: the loss of water from a plant cell such that the cell membrane detached from the cell wall. (plasmolysed)