Diffusion and Osmosis Flashcards
What is diffusion?
Diffusion is the movement of molecules from an area of high concentration to an area of low concentration down the concentration gradient.
What is osmosis?
Osmosis is the movement of water molecules from an area of high concentration to an area of low concentration through a selectively permeable membrane.
Name molecules that can enter a cell by diffusion?
Glucose, Oxygen and Amino Acids
Name molecules that can leave a cell by diffusion?
Urea, co2 and waste products.
If potato cylinders are placed in high salt solutions what happens to them and why?
They lose mass due to osmosis.
Give an example of diffusion?
- Gas exchange of oxygen and carbon dioxide in the lungs
- The movement of glucose across the lining of the gut
Give an example of osmosis
Plants taking up water from their roots.
What is ‘hypotonic’?
What happens to red blood cells?
What happens to plant cells?
More water, less solution.
Cell will burst (lysis)
The vacuole swells - becomes turgid.
What is ‘hypertonic’?
What will happen to red blood cells?
What will happen to plant cells?
More solution, less water
Cell will shrink and shrivel.
The vacuole shrinks - becomes plasmolysed.
What is ‘isotonic’?
What happens to red blood cells?
What happens to plant cells?
Same concentration of solution and water
There is no movement of water - stays the same.
Two main components of the cell membrane?
Describe the properties of plasma membrane?
Proteins and Phospholipids
Phosphate - hydrophilic (loves water)
Lipids - hydrophobic (repels water)
What is active transport?
Active transport requires ATP and moves from low to high concentration against the concentration gradient.
