practical: investigate diffusion & osmosis using living and non-living systems Flashcards
agar cubes of different sizes can be used to demonstrate what?
the relationship between surface area: volume ratio and rate of diffusion
what do the cubes contain?
alkali and an indicator- they are placed in an acid
what happens as the acid diffuses into the cube?
it reacts with the alkali- this neutralisation turns the indicator colourless
which cube becomes colourless the quickest?
the smallest (0.5cm) cube
potato chips are placed into what?
sucrose or salt solutions of different concentrations
what does it cause when osmosis will occur until the water potential of the tissue and the solution are the same?
will cause a mass change
what happens if the solution has a higher water concentration?
water will move into the potato chip and the mass will increase
what will happen if the solution has a lower water concentration?
water will move out of the potato chip and the mass will decrease
what does visking tubing allow?
- only allows small soluble molecules to pass through eg. glucose and water
- therefore, osmosis can occur
what could you increase to investigate the effect on osmosis?
could change the concentration of the sucrose solution or the temperature of the water
what will increase if osmosis is faster?
the height the liquid rises in a set time
if cells are soaked in pure water, they will turn…
turgid
if cells are soaked in a concentrated salt or sugar solution they will turn…
plasmolyzed
what else can you use to study the effects of osmosis?
thin sections of onion cells
