Osmosis

Osmosis is the movement of water from one area to another. It moves to an area that is more sugary or salty. The best way to describe this is "Osmosis is the movement of water from an area of low solute concentration to an area of high solute concentration, through a partially permeable membrane."

You can revise this by simply remembering that water moves to sugary or salty areas through cells.

This investigation aims to find out the concentration of sugar in plant cells, e.g. a potato or carrot. Watch out, they change the veg they test each year!

• The dependent variable is mass of the vegetable at the end of the experiment. A higher grade answer will say it is the percentage change in mass as this is more comparable between vegetables.
• The independent variable is the salt or sugar concentration of the surrounding solution. Usually at least 5 concentrations are needed and this is measure in mol/dm³ or Molar, e.g. 1M, 2M etc.
• There are several variables that need to be controlled. These are the shape, surface area, starting mass of the vegetable, presence of skin on potatoes etc and time left in the solution (which needs to be at least 15 minutes).
• The most common errors are that the vegetables are not dried properly at the end and so they weigh more than they should

At the end, you can find the concentration of sugar in the vegetable by finding the point on the graph where there is no change in mass

Active transport and it requires energy from respiration to do this

Temperature because it gives the particles more kinetic energy, so they move faster

Concentration gradient because there are more particles on one side

Surface area because there is more space for exchange to take place

It is more similar to diffusion because it does not require energy to proceed.

However, it can only take place across a membrane, diffusion can take place without a membrane (smelly armpit smells spread out!).

Active transport can only take place on LIVING membranes because it needs energy.