How to Know the Effect of Placing Cells in a Hypotonic Solution

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how to know the effect of placing cells

How to know the effect of placing cells in a hypotonic solutin is the learning objective of this nature school. You will study osmosis and determine how cells placed in a hypotonic and hypertonic solution affect osmosis. 

science.aksiografi.com – Cell survival depends primarily on its ability to achieve homeostasis. The ability of a cell to maintain a stable internal environment is accomplished by controlling the movement of matter across the cell membrane. If this irritable balance is lost, cells can be injured and even die.

Osmosis is the transger of solvent molecules (such as water) through a semipermiable membrance form a more dilute part to a more concentrated part or from a part with a low solvent concentration (hypotonic) to a high solvent concentration (hypertonic).

This experiment, you will study osmosis and determine how cells placed in a hypotonic and hypertonic solution affect osmosis. The rate at which water moves through the cell membrane of an egg will be calculated and the factors affecting osmosis and turgor pressure will be studied.

Learning Objective

To determine the effect of placing cells in a hypotonic solution (a solution whose water concentration is higher than the concentration of water in the cell.

Materials

jar with a small mouth

straw (clean and transparent)

distilled water

candle with a length of 20 cm or more

raw eggs

metal spoon

matches

CAUTION: Always wash your hands after touching raw eggs. Eggs may contain harmful bacteria.

Procedure

1- Fill the jar three quarters full of distilled water.

2. Gently tap the rounded end of the eggshell with the edge of the spoon.

3. Carefully use your fingernails to peel off small pieces of egg shell. Note: Peel off a small portion of the shell about the size of your fingertip. Be careful not to pierce the thin membrane under the shell.

4. On the other end of the egg, make a hole in the shell big enough to insert a straw.

5. Erect the eggs in the jar filled with water, rounded side at the bottom.

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6. Insert the end of the straw (± 2.5 cm) into the hole of the shell through the cell membrane.

7. Turn on the candle and hold it.

8. Drop the melted wax around the bottom of the straw until the space between the straw and the shell is closed (see Figure below).

figure semipermeable shell membarane

9. Leave the attached eggs and straws in place all night. Do not disturb.

10. Observe every movement of the fluid.

Result

Clear liwuid enters the straw.

Why?

Cell homeostasis is the ability of cells to obtain a stable internal environment by regulating the passage of fluids through the cell membrane. Removing the egg shell opens the semipermeable cell membrane (the egg is a single cell). A semipermeable membrane is a membrane through which only certain substances can pass but others cannot. The water molecules are small enough to move across the membrane, but the molecules inside the cell are too big to leave the cell. This movement of water across the membrane is called osmosis .

Osmosis occurs when there is a difference in the concentration of water in two solutions separated by a membrane. The water concentration in the jar is 100%. The water concentration in egg liquid is less than 100% because fat, protein and other substances dissolve. Water moves through each cell membrane from areas with high water concentration to areas with low water concentrations. In this way, the water in the jar moves across the egg membrane towards the inside of the egg. When water gets into the egg, the volume of liquid in the egg increases so that additional molecules are pushed up the straw. This power is generated by osmotic pressure (the pressure of water diffusing through a semipermeable membrane). The greater the difference in fluid concentration on the two sides of the membrane, the higher the osmotic pressure.

Try New Approaches

1. How long does it take for the liquid to fill the capacity of the eggs? Repeat the experiment measuring the time from the time the eggs are placed in the water until the liquid appears at the bottom of the straw.

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2. Does the surface area of ​​the membrane affect the rate at which water flows into the eggs? Repeat the initial experiment showing more membranes by peeling off the larger parts of the shell. Measure the time it takes to fill the egg again. Instructions for Science Contests and Exhibits: Prepare an egg with a straw for display. Show me photos to illustrate the various experiments and their results.

3. After the egg has filled its capacity, at what speed does the water flow into the egg? Is the next speed the same? To find the answer to this question, use a fully loaded egg. Use a marker to mark the level of liquid in the straw every 1 hour for 8 hours or until the straw is filled. Use the distance marking to determine if the flow rate is constant. Instructions for Science Contests and Exhibitions: Also display pictures showing the water level in the straw in the project report as well as part of the project fair.

Design Your Own Experiment

1. Do cell become dehydrated (lose water) when placed in a hypertonic solution (a solution with a low water concentration)? Mix one tablespoon (15 ml) of table salt with 8 ounces of water. Pour the salt solution into a bowl. Cut 4 potato slices 6 mm thick. Soak the potato slices in salt water. After 15 minutes, cut the potato again and test the strength of the potato slices by bending the potato slices with your fingers. Test the strength of the potato slices in a salt solution. The reduced strength indicates that water has left the cell. Then the cells lose turgor pressure (pressure inside the cell due to the presence of water). Try testing with different objects and solutions. Show off the pictures to show the results.

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2. What happens to plants that live in fresh water? What stops the flow of water into plant cells? Prepare a few wet slices of elodea leaf. See Appendix 1 for the steps for making a slice. Use a microscope to observe the slices. With high and low magnification, observe the structure of each cell and pay attention to the cell walls. Remove the water from the cells by adding a few drops of table salt solution (made from 15 ml sodium or sodium chloride / table salt in 125 ml water) (see Figure above). Observe the cell structure in the salt solution. Squeeze out the saline solution by placing a paper towel over the edge of the lid. Add a few drops of distilled water to the edge of the cover glass, while looking at the cells through a microscope. You will observe cells shrinking in the salt solution and enlarging in the water. Cells rarely expand until they break / their outer cellulose walls can withstand the pressure.

Figure 1

Find Out the Facts

1- Freshwater animals, such as fish and protozoa, do not have strong cellulose walls to protect them from constantly entering water due to osmotic pressure. How do the cells of these organisms protect themselves? Find out how energy is used to pump the excess water back out. What are the contractile vacuoles, which organisms have them, and how do they function?

2. Why do freshwater plants wither when placed in salt water, while marine organisms survive even though every day in salty sea water? What does it mean when we say that seawater is isotonic for the cytoplasm of marine organisms, but hypertonic for the cytoplasm of freshwater organisms? What does plasmolysis mean

3. Human kidneys continuously filter blood, excrete waste, and maintain a proper balance of water and salt. An artificial kidney machine is used to perform the same function. How does this machine work? How does the machine use the osmosis process to wash the blood?

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