Osmosis Flashcards
Define osmosis
Osmosis is the passive movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration down a water potential gradient
What is a partially permeable membrane?
One with small holes in it so only small molecules can pass through them
Why do molecules move both ways through the membrane?
Molecules move randomly - it is the net movement we focus on in diffusion and osmosis
Give the word to describe lots of water and few sugars
Dilute
Give the word to describe lots of sugar and few water
Concentrated
What is meant by passive movement?
No ATP/energy is required
Describe an experiment you would use to observe the effect of sugar solutions on plant tissues
Cut up a potato into evenly sized identical cylinders and place in beakers of different sugar concentrations
Measure the mass of cylinders then leave in beakers for 24 hours
Take the cylinders out and dry them with a paper towel and measure their mass
Calculate the percentage difference in mass and plot on a graph
What is the dependent variable in the potato experiment?
The potato mass
What is the independent variable in the potato experiment?
Concentration of the sugar solution
What are the control variables in the potato experiment?
Volume of solution
Temperature
Time
Type of sugar used
If the potato gained mass what does this mean in terms of osmosis?
Water has been drawn into the potato
Less sugar and more water outside than inside
What errors may arise in this experiment?
Cylinder may not be dried properly so excess water may give a higher mass
Water may evaporated from beaker changing the concentration of sugar solution
How can errors be reduced?
Repeating the experiment
Calculate mean percentage change
