Experiment Biology Form 4

Experiment Biology Form 4 Title: movement of substances across a semi-permeable permeable membrane. Aim

:________________________________________________________________

Problem statement

: What factor influences the diffusion of substances through a semi-permeable membrane?

Hypothesis

:_________________________________________________________________

Variables

Materials

manipulated variable

:_____________________________ :_____________ _______________________________ _______________

Responding variable

:_____________________________ :_____________ ________________________________ ________________

Constant variable

:______________________________ :_____________ ________________________________ _______________

: Benedicts solution, 1% starch suspension, iodine solution, 30 % glucose solution and distilled water.

Apparatus

: a Visking tubing, cotton thread, test tubes, beakers and a Bunsen burner.

Procedure

:

1. Wet one Visking tubing. Tie a knot firmly at one end. 2. Pour 10ml of glucose solution and 10ml of starch suspension into the Visking tube. Tie a knot at the top of the tubing. Record the colour of the mixture. 3. Rinse the outside of the Visking tubing using distilled water. 4. Pour 300ml of distilled water into a beaker. Add in 10ml of iodine solution. Record the colour of its solution. 5. Immerse the Visking tubing in the be aker of solution for 3o minutes as shown in the diagram.

6. After 30 minutes, remove the Visking tubing and transfer it into a dry beaker. 7. Record the colours of the contents in the Visking tubing and the solution in the beaker. 8. Test for the presence of glucose g lucose in the content of the Visking tubing and the solution in the beaker using the following steps: a.

Pour 2ml of the solution into a test tube and add in 1ml of Benedicts solution.

b. Heat the mixture in a beaker of water bath. Record the change in colour.

Result:

Solution in

Contents

Iodine test Initial colour

Final colour

Benedicts test

Visking tubing Beaker Discussion: 1. Based on the result, make an inference on the size of the iodine molecules as compared to starch molecules. 2. Compare the size of glucose molecules with starch molecules. 3. Based on the results of this experim ent, explain briefly the importance of the breakdown of  starch to glucose in the digestive canal. Conclusion: Is the hypothesis accepted? Restate the hypothesis.

Miss ayunee/SMKL