L3: OSMOSIS

L3: OSMOSIS


1. Introduction

Osmosis is the spontaneous movement of solvent molecules through a semipermeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides. 

When the extracellular concentration is hypertonic, water moves out of the cell and the cell becomes flaccid: plasmolysis.
When the extracellular concentration is hypotonic, water moves inside the cell and it becomes turgid.


2. Objectives

• Know about the osmosis phenomena.
• Understand the process of osmosis in plasmatic membranes. 

3. Hypothesis

The hypothesis is that in the experiments with an egg and a potato, the osmosis going to happen from the plasmolysis and turgid. 

4. Material

• Egg
  
• Potato
  
• Salt
  
• Distilled water
  
• Acetic acid (or vinegar)
  
• Spatula
  
• 600 mL Beaker
  
• 3 Clock glass
  
• Pen
  
• Spoon
  
• Knife 
  

5. Procedure

EGG

First of all, we took a beaker of 600 ml and then, we put the acetic acid and egg into the beaker. After that, not only did we removed it with a spoon but, we covered it as well.

Now, we'll let the beaker rest some days and then, we'll look if the egg has grown  by the turgid process. Some days later, the egg was bigger so we put salt to look if the egg was going to do the plasmolysis process and it was like we thought.

Grams per egg:

1) Normal egg: 188,1gr

2) Turgid : 209gr

3) Plasmolysis: 192 gr

POTATO

Fist of all, we took a potato and then, we cut on three pieces and we did a whole in the middle of every single piece of potato.

We didn't put anything on the first piece because it was the proof one.

On the second piece, we put salt in the whole and theoretically was going to do the plasmolysis process.

On the third piece, we put distilled water in the whole and theoretically was going to do the turgid process and it was like we thought.

6.Observations

In two experiments we have observed that our hypothesis was true.

7.Conclusions

On one hand, if we put salt in some aliment, the concentration of salt will be bigger out. In consequence of that, water will apear by the plasmolysis process. On the other hand if we put a distilled water the concentration will be bigger out. In consequence of that, water will disappear by the turgid process.

8.Questions 

Egg experiment:

1. What is happening when the shells are soaking of acetic acid?
   
   The acid acetic disolt the shells.
   
   
2. Write the results of de dimensions and weigh of the egg before and after immersing it in distilled water. Write and draw a simple diagram of the water direction.
   
   
   1) Normal egg: 188,1gr
   2) Turgid : 209gr
   
   
   3) Plasmolysis: 192 gr
   
   

Potato experiment:

3. Explain the results of this experiment.
   
   On one hand, if we put salt in some aliment, the concentration of salt will be bigger out. In consequence of that, water will apear by the plasmolysis process. On the other hand if we put a distilled water the concentration will be bigger out. In consequence of that, water will disappear by the turgid process.
   
   
4. Why have we left the first slice without any treatment (salt or distilled water)?
   
   To compare all the other proofs.
   
   
5. Which are the dependent and independent variables?
   
   The dependent variable is that you modificable and the independent variable is that change alone.

General questions:

6. How can you explain (through osmosis) the ability of plan trots to draw water from the soil?
   
   The capilars.
   
   
7. What will it happen if a saltwater fish is placed in a freshwater (low concentration of salts) aquarium?
   The fish would inflate.
   
   
8. Look the image you have below and explain what is happening to the erythrocytes in each situation: 
   
   1. plasmolysis
   
   2. control
   
   3. turgid