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My name is Poon Cheng Moh. I have been teaching biology in SMK(P) Raja Zarina, Port Klang for 26 years. I sincerely hope that this blog on SPM Biology will be useful to both teachers and students.

Thursday, April 11, 2013

Answers to Amali Proses Sains Pg 15-17



Aim : To study the movement of substances across a semi permeable membrane.
Hypothesis: Molecules which are smaller than the pores of the Visking tubing are able to move across the plasma membrane
MV : Size of solute molecules
RV : Colour of Iodine/Benedict  solution
FV : Temperature/time

Solution in
Content
Iodine test
Benedict test
Initial
Final
Visking tubing
Glucose solution + starch suspension
Colourless
Dark blue
Red precipitate
Beaker
Distilled water + iodine solution
Yellow
Light yellow
Red precipitate

Discussion
1.       Iodine molecules are smaller than the starch molecules. Thus the iodine molecules are able to move into the visking tubing while the starch molecules cannot move out from the visking tubing.
2.       Glucose molecules are smaller than the starch molecules.
3.       Starch needs to be hydrolysed to glucose in the alimentary canal so that the glucose molecules are small enough to diffuse into the epithelium cells of the villi and into the blood capillaries.

Conclusion
Yes, the hypothesis is accepted. Molecules which are smaller than the pores of the Visking tubing are able to move across the plasma membrane.

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