U.C.E BIOLOGY 2005 PAPER 1 QN 31

Six identical potato cylinders measuring 2.0 cm in length were each placed in a different concentration of sugar solution. After two hours, the potato cylinders were removed from the solutions and remeasured. The table below shows the results.

Concentrations of sugar solutions mol I -1              length of potato cylinders after 2 hours (cm).               Difference in length of potato cylinders after 2 hrs (cm).

0.1

0.2

0.3

0.4

0.5

0.6

2.40

2.25

2.15

2.05

1.98

1.02

a) Complete the table by filling in the difference in length of each potato cylinder after two hours (i.e. length after 2 hours subtract initial length)

b) In the space provided plot a graph of the difference in length after 2 hours against concentration of sugar solutions.

c) (i) What was the effect of the concentration of the sugar solutions on the length of the potato cylinders?

(ii)Explain why the concentration of the sugar solutions affected the length of the potato cylinders as stated in (c)(i).

d) (i) From your graph, determine the concentration of the sugar solution that would give no difference in length of a potato cylinder.

(ii)Explain what happens in a potato cylinder when no change in length occurs.

e) Suggest one other observation other than change in size that would be made on the potato cylinders.

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