Diffusion and Osmosis Flashcards
Are all biological membranes similar?
Yes
What do selectively permeable membranes do?
Allow some substances to pass through easily, but other substances cannot pass through easily.
What is diffusion?
Movement of molecules from a region of higher concentration to a region of lower concentration.
What is active transport?
Movement of molecules from a less crowded area to a more crowded area with the use of energy.
Name four membranes in plant and animal cells.
- Cell membranes
- Mitochondrial membranes
- Chloroplast membranes
- Nuclear membranes
Do all membranes act in the same way?
Yes.
What does permeable mean?
It means it lets everything in and out
What does semi-permeable mean?
Lets some things in and out
What does impermeable mean?
Lets nothing in and out
Give an example of a material that has a selectively permeable membrane.
Visking tubing
What does diffusion occur in?
-Liquids and gases
Does diffusion need energy?
No, it is passive
Give a few examples of diffusion in everyday life.
- Smell of perfume
- Bread baking
- Stink bomb
- Food colouring in water
- Sugar in tea
What is a solvent?
Liquid that dissolves the solute
What is the solute?
Substance that has been dissolved
What is the solution?
Mixture of solute and solvent
What is osmosis?
Is the movement of water across a semipermeable membrane from a region of high water concentration to a region of low water concentration.
Is osmosis passive?
Yes
What happens to an animal cell surrounded by a solution that is the same concentration as the cytoplasm in the cell?
Water will move in and out at the same rate and the cell will remain intact.
Are plant cell walls fully permeable?
Yes
What does turgor mean?
When water enter the plant cell, leading the swelling of the cytoplasm and vacoule, meaning the membranes push against the cell wall
What does this turgor pressure do?
Give plants their strength, without it plants will wilt.
What is plasmolysis?
When the cell wall stays intact but the membrane shrivel up away from it due to water loss (osmosis)
Is osmosis used in food preservation?
Yes. If food is placed in a sugary or salty solution then any bacteria or fungi present will lose water in their cells to the more concentrated solution outside
Name examples of osmosis and food preservation.
- Fish and meat may be stored in a salty solution
- Jams, marmalades and tinned foods are stored in a sugary solution
How do amoeba survive in freshwater (less concentrated environment)
They have a contractile vacuole which eliminates water.
