Effects of osmosis on plant tissue

Define osmosis

the diffusion of water from an area of high water potential to an area of low water potential through a partially permeable membrane

What happens when water osmoses into a cell?

it expands and becomes turgid

What happens when water osmoses out of a cell?

it shrinks and shrivels

How do we prepare the plant sample? (potato)

1. peel the outer layer of skin as it can affect osmosis

2. use a cork borer to produce 3 cylinders of potato

3. use a scalpel to trim the pieces to 3 cm in length

4. Measure each cylinder’s length and mass

How do we carry out the experiment?

1. place each cylinder into a test tube

2. add 10cm³ of 0.5 molar sugar solution, 0.25 molar sugar solution and distilled water into one test tube each with the potato cylinder inside

3. leave the potatoes overnight

4. gently pat the cylinders to remove surface moisture, but do not press on them as to not force any water out of it

5. measure the new length and mass

6. calculate the percentage change in mass

Why do we use distilled water?

tap water can have other additives or chemicals that can affect the rate of osmosis

What is the formula for percentage change?

(change in value/original value) x 100

What is the independent variable?

The concentration of sugar solution in moles

What is the dependent variable?

percentage change in mass

what does it mean when the % change in mass is 0?

equilibrium has been reached

What does the concentration of sugar in the solution at equilibrium tell us about the cell?

the concentration of sugar in the cell would be equal to the concentration of sugar in the solution