Osmosis

1. Definition

1.1. A special case of diffusion

1.2. = ONLY the movement of WATER molecules from a dilute or less concentrated solution (ie lots of water molecules) to a more concentrated solution (less water/more chemicals)

1.3. water moves through a partially permeable membrane

1.4. watch the language of what is concentrated!

1.5. Difference between the concentrations of solutions inside and outside a cell cause water to move in/out of cell by osmosis

2. Importance for cells

2.1. osmosis allows WATER to move in and out of cells

2.2. so osmosis keeps cells at correct concentration ie in balance so they work properly eg maintaining body temperature or supporting plant tissues

2.3. osmosis is therefore critical to keep cells at optimum balance

2.4. cytoplasm contains chemicals eg salt/sugars contained in water

3. Diffusion

3.1. occurs when particles spread freely from one place to another

3.1.1. Project specifications

3.1.2. End User requirements

3.1.3. Action points sign-off

3.2. From a high concentration of those molecules moving to a region of low concentration

3.2.1. Define actions as necessary

4. Animals cells

4.1. if cell uses water up in its chemical reactions water moves in by osmosis and balance restored

4.2. Issue 1 - too much water moves into cell -it will explode and burst

4.2.1. cell swells and bursts

4.3. Issue 2 - too little water moves into the cell and it will shrivel and die

5. Plant cells

5.1. plants rely on osmosis to support stems and leaves - need fluid surrounding cell to be always more dilute than inside

5.1.1. Dependencies

5.1.2. Milestones

5.2. solution outside cell is more dilute = water moves into cell by osmosis = vacuole swells = presses the cytoplasm against the plant cell walls = no more water can move in = cell is rigid and hard

5.2.1. Schedule

5.2.2. Budget

5.3. Issue - if solution outside cell is too concentrated then water move out of cell via osmosis and cells will not support plant tissues and plant will die

5.3.1. KPI's