Lab - Exercise 2

Question 1

Osmosis

Answer 1

Movement of water molecules through a porous membrane with their concentration gradient (hypotonic to hypertonic) (kidneys)

Question 2

Filtration

Answer 2

Movement of molecules through a porous membrane using hydrostatic pressure (molecules leaving capillaries)

Question 3

Sugar test results: change in color to green, yellow, orange or red indicates what?

Answer 3

The presence of simple sugars

Question 4

Iodine test for starch: a change in color to purple, dark green or black indicates what?

Answer 4

The presence of starch

Question 5

Why is it necessary to test both the original solution and the filtrate?

Answer 5

1. To confirm that you know how to perform the tests
2. To confirm that all reagents are working properly
3. To have a positive control test for comparison of your “unknown” results

Question 6

Why does ocean water not make your skin wrinkle like swimming pool water?

Answer 6

The ocean water contains more salt than the pool so it’s hypertonic to skin. Therefore skin loses water to the ocean. The pool water is slightly hypotonic to skin.

Question 7

Diffusion

Answer 7

Movement of molecules through a membrane from high concentration to low concentration (breathing)