L3. Osmosis

Introduction:

This is a lab on osmosis. Today we will see how a hypertonic medium and a hypotonic environment. We will also see the difference between the concepts isotonic, plasmolysis and turgidity.

Objectives:

1.      Know about the osmosis phenomena.

2.      Understand the process of osmosis in plasmatic membranes.

Hypothesis:

·       

       When you add a lot of salt in a medium, this wrinkle, leaving ana water. When you add a quantitad of distilled water in a medium swell.

Materials:

·         Egg

·         Potato

·         Salt

·         Distilled wáter

·         Acetic acid (or vinegar)

·         Spatula

·         600 mL Beaker

·         3 Clock glass

·         Pen

·         Spoon

·         Knife

Procedure:

·          Cut three pieces of potato peers. By adding a high concentration of salt, the other add distilled water, and the third adds nothing. Let us spend a while to look after a while each sample. 

                      

        Put an egg in a Beaker 600 mL of distilled water. Let us spend a couple of days. Having spent time look egg.

Comments:

·          The potato has been inflated with distilled water, salted potato has wrinkled potato has nothing, as usual. There    is an acute process of osmosis.

Conclusions:

The potato has been inflated with distilled water, salted potato has wrinkled potato has nothing, as usual. There is an acute process of osmosis. 

The egg has been inflated. He suffered a turgidity. 

Questions:

·         Egg experiment:

1.       What is happening  when the shells are soaking of acetic acid?

-          CaCO3 + CH3COOH                 Ca (CH3COO)2 + CO2

2. Write the results of the dimensions and weigh of the egg before and after immersing it in distilled wáter. Write and draw a simple diagram of the water direction.

·         Potato experiment:

3. Explain the results of this experiment:

- The potato has been inflated with distilled water, salted potato has wrinkled potato has nothing, as usual. There is an acute process of osmosis. 

      The egg has been inflated. He suffered a turgidity.

4. Why have we left the first slice without any treatment (salto r distilled water)?

- To compare the results

5. Which are the dependent and independent variables?

-        Dependent: Turgidity of the potato, the presence of water in the cells

-        Independent:salt, distilled water

·         General questions:

6. How can you explain (through osmosis) the ability of plant roots to draw water from the soil?

- The salt concentration of the cells is higher, so water tends to enter.

7. What will it happen if a saltwater fish is placed in a freshwater (low concenttration of salts) aquarium?

- It will die

8. Look the image you have below and explain what is happening to the erythocytes in each situation:

       1) Plasmólisi

       2)Control

       3)Turgid