Digestion & Nutrition - The model gut

Question 1

What is the Visking tube ?

Answer 1

A semi-permeable membrane

Question 2

What materials are used in the model gut ?

Answer 2

-Visking tube
-Starch and sugar solution
-Distilled water
-String (tied to seal)

Question 3

What is the first step in the model gut experiment ?

Answer 3

We start by preparing a mixture of
starch and sugar, which we
know was present because
iodine and Benedict’s test
done at beginning.

Question 4

What is the second step of the model gut experiment ?

Answer 4

After ten minutes we should have found no starch in the surrounding water, but we should have found sugar

Question 5

Why should we find only sugar in the surrounding water ?

Answer 5

Starch is a big molecule, too big to be able to diffuse out of the Visking tube into the water, but sugar is a small molecule, meaning it can fit through the holes in the tubing.

Question 6

Why would a Benedict’s solution be positive for the surrounding water of the model gut test ?

Answer 6

There was a high concentration of sugar on the inside of the tube and a
low one outside, so sugar diffused out.

Question 7

Why was starch not found in the surrounding water?

Answer 7

It is too large a molecule to pass
through the walls of the tube

Question 8

Why was sugar found in the water?

Answer 8

It is a small molecule and could move out
through the Visking tube walls

Question 9

What do we call a membrane that only allows some molecules through and not others?

Answer 9

Partially permeable/ semi-permeable