required practical - osmosis

Question 1

explain the process of investigating the effect of osmosis on plant tissue

Answer 1

1. peel the potato - potato skin can effect osmosis
2. use a cork borer to produce three cylinders of potato - ensures the same diameter
3. use a scapple to trim the cylinders to the same length
4. measure the length and mass of the cylinders
5. now place each cylinder into a test tube. 6. add 10cm cubed of 0.5 molar sugar into test tube one, 10cm cubed of 0.25 molar sugar in test tube two and 10cm cubed distilled water in third
6. leave overnight to allow osmosis to occur
7. then remove any surface moisture using a paper towel
8. re measure length and mass of each cylinder

Question 2

how do you calculate the percentage change

Answer 2

change in value/ original value x 100

Question 3

draw a graph which would present the information

Answer 3

% change on the side
concentration of sugar line in middle

going from 0 - 0.25 - 0.5
line start from top of graph
crossing x axis between 0.25 and 0.5
ending at bottom

Question 4

why does the graph start at the top when concentration is 0

Answer 4

in water, the potato gains mass as water moves in by osmosis

Question 5

why does the graph cross the x axis between 0.25 and 0.5

Answer 5

there is no change as the concentration outside is the same as inside

Question 6

why does the graph end when concentration is 0.5

Answer 6

in concentrated sugar, potato looses mass as water moves out because of osmosis