L3: Osmosis

Introduction:

Osmosis is the spontaneous movement of solvent molecules through a semipermeable membrane into a region of higher solute concentration (hypertonic), in the direction that tends to equalize the solute concentrations on the two sides. Osmosis is a vital process in biological systems, as biological membranes are semipermeable. Water molecules travel through the plasma membrane in order to equilibrate the intra and extra cellular concentrations.When a cell is submerged in water, the water molecules pass through the cell membrane from an area of low solute concentration to high solute concentration.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.

Objectives:

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


Materials:

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

Procedure:

Egg: this experiment will be divided in two days.
Under the hard outer shell of a chicken egg is a semipermeable membrane that allows air and moisture to pass
through. Because water molecules can move into and out of the egg but larger molecules cannot, the
semipermeable egg membrane allows for an exploration of concepts of diffusion and osmosis.

1st Day:
Before the egg osmosis experiment can begin, the egg’s hard outer shell must be removed. Let’s start with
this:
1. Take a 600mL beaker and put inside the egg.
2. Cover the egg with vinegar and make note of what’s happening.
Once the egg’s shell is removed and the egg is rinsed dry and clean, measure and weigh the egg. Record
the dimensions of each egg in a table.
3. Clean the beaker and put the egg inside again.
4. Cover it with distilled water. Make note of the volume of solution inside the beaker.

2nd Day:
5. Left the egg one day in the distilled water. After about a day, carefully remove the egg using a spoon.
Rinse the egg with water and let it dry.
6. Measure again the dimensions and record its weight.
7. Make note of the solution volume in the beaker and notice if there has been any difference.
8. Observe the results and write your conclusions in your lab worksheet.

Potato:
1. Lay out the three watch glass.
2. Slice the potato in three parts lengthwise. Each slice must be of 1,5cm thick.
3. Place each slice onto a watch glass and make a hole in the middle of each slice. NOTE: the hole does not
have to cross the slice!
4. In the first slice hole, don’t put anything. The second fill it with salt and the third with distilled water.
5. Left this preparation 30 minutes and make note of what is happening.

Observation of the egg :

First he gave off carbon dioxide disappeared after the first layer of skin that was semiperneable and become whiter in color with a touch different
Obserbacio potato :

the potato that we did not even throw salt or distilled water was oxidized to which we possa salt water to loosen regulate hypertonic saline became so limp became more however was softer potato with distilled water swelled and stood among them is the process of Turgut was hypotonic
conclucio potato
If the potato strips salt will lose water and distilled water if litires cells sinflaran harder and tare
Conclucio egg:


Questions;

Egg experiment:

1. What is happening when the shells are soaking of acetic acid?Sestan disolen dejuta l'acid que les va desfem pero una de les petxines no es va desfer perquè era mes resistien i no libem tirar suficient acit clorhídric, les altres el van desfer i va quedar nomes la part inorgànica.

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.

Potato experiment:

3. Explain the results of this experiment.La patata amb sal es va tornar mes tova perque sigualesin les consentracions de sal va haver de despendre aigua i l'altre va absorvir l'aigua destilada per igualar la solucions
4. Why have we left the first slice without any treatment (salt or distilled water)? Per que el resultat sigui en las mateixes condicions amb les mateixes patates el mateix   ambient utensilis i que poguem compra els resultats
5. Which are the dependent and independent variables?les dependents seria l'aigua destil·lada i la sal i la independent la patata sense modificar
General questions:
6. How can you explain (through osmosis) the ability of plant roots to draw water from the soil?
Per que es necessita regular la concentració de salts i les plantes absorbeixen aquestes salts del terra i la pluja per regular les dissolucions i que siguin isotòniques

7. What will it happen if a saltwater fish is placed in a freshwater (low concentration of salts)
aquarium? El peix esta acostumat a viure en unes condicions  que l'aigua dolça no te, la salinitat del cos d'aquest peix baixaria i es moriria

8. Look the image you have below and explain what is happening to the erythrocytes in each situation:
A la primera hi ha un increment de sal i els globuls vermells es quedarien sense aigua esta patim un proces hipertonic , la segona es regula perquè te una quantitat estable de aigua i de sals, la tercera te un augment d'aigua destil·lada que faria perdre sals per aixó si veguesim aigua destil·lada ens podrirem mori