Biology Practical to study the Osmosis effects of Sucrose solutions of different Molarities upon Plant Cells (Chinese Radish and Potato Chips) By lamest An Experiment to investigate Osmosis in Plant Cells Aim The aim of this experiment is to investigate the movement of water by osmosis in and out of plant cells across a semi permeable membrane in sucrose solutions of different concentrations.
The plant cells used in the experiment are potato and Chinese radish tissues that are used as chips because the results and changes are easy to note and record in this way. As plant cell membranes are differently remarkable, different results are expected from the Chinese radish and potato chips in the same conditions; this is one reason for having two types of plant cell and not one. Another reason is that the two types of plant cells results can be compared and the similarities between certain results compared.
The results taken during the experiment can be used to work out information that will help further our understanding of how osmosis takes place in different plant cells (potato and radish), what physical and biological change may take place, and link certain factors presented in our results to prove information useful to the investigation. Such a point would be to work out at what concentration equilibrium takes place in the chips and how length, mass and concentration affect the results of osmosis (e. G. Flaccid, Playmates etc. , and how to link physical results such as if a potato chip floats or sinks to the mass of a potato chip and the concentration of the solution it was in. Using the results recorded during the experiment, the cell sap sucrose concentration of each chip can be worked out. Overall, the experiment must be planned and osmosis in plants researched so as to predict what should happen in each of the situations presented in the method. The experiment taking place and recorded in the most accurate conditions possible, the most useful results recorded and presented in a helpful way.
The results of the experiment should then be analyses and explained in terms of osmosis and why each result happened discussed and linked to other situations of osmosis. The Tindal section to this investigation should look back on the experiments, criticizing and improving sources of error and finally furthering research by going more into detail on the subject and expanding the research now that the basics of the subject have been covered. Background Scientific Information Equilibrium- There are two types of equilibrium.
Dynamic equilibrium is when two opposing actions occur at the same rate, in the case of osmosis this is water moving in and out of a cell at the same rate. Static equilibrium is when there is no action taking place; this will not take place during this experiment. Osmosis- This is the movement of water molecules from an area of high water potential (a dilute solution) to an area of low water potential (a concentration). This occurs across a semi permeable membrane until equilibrium is achieved. Concentration- When a substance dissolves in water, its molecules attract some of the water molecules and stop them moving freely.
This reduces the concentration of the water molecules as less water molecules are free. Water Potential- This is a measure of whether a solution is likely to gain or lose water molecules from another solution. A dilute solution is said to have a higher water potential than a concentrated solution as it has more free water molecules. Water will flow from the dilute to the concentrated across a semi permeable membrane. Distilled water has the highest water potential, if any aqueous solution was placed cross a semi permeable membrane to the distilled water, the distilled water molecules would flow to it.
Hypersonic Solution- This solution contains a higher concentration of solute compared to another solution (e. G. The cell’s cytoplasm). When a cell is placed in hypersonic solution water will diffuse out of the cell. Hypotonic Solutions- This solution contains a low concentration of solute compared to another solution (e. G. The cell’s cytoplasm). When a cell is placed in hypotonic solution water will diffuse into the cell. * http://www. DVD’s. On. Ca/western/science/Sabina/Cells/Osmosis. HTML Isotonic Solutions- This solution contains the same concentration of solute as another solution (e. G. He cell’s cytoplasm). When a cell is placed in an isotonic solution, the water diffuses into and out to the cell at the same rate. Osmosis in Plants Typical Plant cell (no chloroplasts): Unlike osmosis taking place in animal cells, the cell wall does not prevent the uptake or loss of soluble molecules; it is the plasma/cell membrane which acts as a barrier or semi permeable membrane. The cytoplasm of a plant cell and the cell sap in its vacuole contain sugars, salts and proteins that reduce the amount of free water cells. While the cell wall is fully permeable, the cell membrane is partially permeable.
This presents four cases of osmosis. After osmosis in a plant cell, four situations may result due to osmosis taking place in the cell. These depend on the concentration of the solution the plant cell has been placed in, and the water potential of the plant cell. Cell membranes are completely permeable to water therefore the water potential the cell is exposed to can have a dramatic effect on the cell. Procedure Apparatus: Below is a list of apparatus used to conduct the experiment and take down accurate results: xx Test Tubes – 6 for Potato chips, 6 for Chinese radish.
Each 2 test tubes will have one of the prepared sugar/water solutions inside. 2 chips (CM and CM) from the same plant sample (potato or Chinese radish) will be placed in each test tube. – xx Labels – To label test tubes with different contents (solutions + chips). – Test Tube Rack – To safely hold the test tubes. – Ruler – To measure the length the chips are required to be cut to. – Clean White Tile – To ensure cutting of the chips is safe and that no moisture or dirt is accumulated from another cutting surface.
Clean Scalpel – To cut the chips to their required lengths accurately and easily in conjunction with the ruler. – Top pan balance – To accurately state the mass to each chip. – Watch – To make sure each set of chips remain in their solutions for the same time. – xx 10. Ml Syringe – To prepare the solutions needed for the experiment (1 for H2O and 1 for 1. 0 molar sucrose solution), there are 2 to ensure the H2O and sucrose solution do not mix inside the syringe to affect the sucrose concentration of the solutions and hence give inaccurate results. 1. 0 molar Sucrose Solution – Needed to prepare the solutions. H2O (distilled water) – Needed to prepare the solutions. – Potato Chips – All cut from the same potato to give more accurate results (the chips still need to be cut to accurate sizes) and wrapped in foil to preserve unchanged until experiment (moisture, dirt, etc… ). – Chinese Radish Chips – All cut from the same Chinese radish to give more accurate results (the chips still need to be cut to accurate sizes). – Forceps – to handle chips without leaving dirt or moisture. Sieve – to remove chips after osmosis from test tubes. Method: Below are the instructions used to conduct the experiment and collect exults using the apparatus mentioned. 1. Label Test tubes by concentration (2 of each) and place in test tube rack. 2. The first step is to make the solutions in which the chips will be placed. To do this the correct ratios of distilled water and 1. 0 molar sucrose solution need to be worked out (in each test tube there is 1 ml of solution): Conversationalist’s Waters . Molar Sucrose Solicitousness 0. 0 molar monomial 0. 2 molar 12m13m115ml 0. 4 molar9m16m115ml 0. 6 molar6m19m115ml 0. 8 molar3m112m115ml 1. 0 molarOm115m115ml When the correct ratios have been worked out, the required amounts of sucrose solution and H2O must be taken from the H2O and Sucrose Solution (using different syringes) and placed in the test tubes labeled with the correct concentration (each concentration should be put in two of the test tubes as one is for the Chinese radish and one for the potato). 3.
The Potato and Chinese radish chips are supplied cut roughly as rectangular prisms: – cut each chip to CM (at right angles) vertically on tile measuring using ruler and cutting using scalpel. (When using scalpel always cut away from body and making sure no body parts are in the scalpels way). Cut each CM chip into CM and CM segments (at right angles) on tile measuring using ruler and cutting using scalpel. 4. Weigh each chip using top pan balance (making sure you know which chip has what mass) and record its initial weight in a table against the concentration of the solution it is to be placed in (in grams). Place one CM and one CM chip to either the potato or the Chinese radish into the solution you said it would be in the table with tweezers noting down the time. This should be repeated for all the chips with intervals of 1 minute (as this gives you time to note the changes and observations). Leave in for as long as possible (at least 40 minutes). 6. After 40 minutes check if the chips floated or sank tip test tube holding first set of chips into sieve over sink. Place chips on white tile, measure and record their final lengths and record other observations.
Weigh each chip and record its final mass. Repeat for rest of chips at 1 minute intervals from time taken out (NOTE RESULTS). 7. CLEAR UP! Diagram of experimental set up: Collecting Results: In each case osmosis will occur. Some of the potato and radish tissue will gain water by osmosis, while others will lose water, unless equilibrium has occurred, these will lead to changes in length and mass that can be recorded against the initial lengths and masses accurately. This will allow further analysis of osmosis in plant cells and factors such as the cell sap sucrose concentration to be worked out.
To make sure that the results recorded are accurate, several precautions must be taken: – The chips must be cut from the same plant tissue (potato and Chinese radish) in order to have the least variation in growing and handling conditions that could have affected the plant tissue such as a different concentration of salts in the round during growth that could affect results and cause big differences between the results to one chip and another it they came trot samples of potato or Chinese radish. Efferent – The chips must be cut as accurately as possible to the same size, although this measurement is still inaccurate as length is not as useful as the much more accurate measurement of volume that could not be used in this experiment. – The solutions must be prepared accurately, making sure there are no air bubbles in the syringes and that they are filled to exactly the mark required at ye level so the volume of solution inside each syringe is accurate.
The syringes must also be kept in their correct beakers in order to ensure that the two solutions within the beakers are not mixed within the syringes causing inaccurate preparation of the solutions. – The test tubes used must be clean and moisture free as well as all the other apparatus used in contact with the chips in order to ensure an accurate environment which will not affect the experiment. The apparatus not in contact with the chips must be clean, yet some of these instruments must have some moisture on them (e. G. Syringes). The experiment should also be conducted at room temperature and preferably not in humid conditions that could affect the chips. – The measuring instruments must also be accurate and clean and moisture free so as to give accurate results. Safety precautions must also be taken so no damage will occur. Although this experiment is a safe one, several precautions must still be taken: – The experiment must be set up away from any hazards that may knock it over and ruin it and be set up stable tort the same reason and so none to the solution will spill, the test tube rack does this.
The cutting must be done away from the body as the scalpels blade is very sharp and no obstructions should be put in its path in case the user slips, this could be very hazardous. The scalpel should be put in a safe place. If a person does cut themselves the blood should be hygienically removed and not be in contact with another person. – The worktop and area should be kept clean and tidy with nothing on it except the apparatus used in the experiment in order to reduce the chance of an accident taking place or the apparatus getting knocked over (someone tripping over a bag).
This also creates a better working environment. Recording the Results: If all the safety and accuracy precautions are taken, an accurate set of results should be given, yet the results still need to be recorded. The following results must be taken: Variables Independent Variables: This is the variable that is chosen by the researcher, the concentrations of the solutions were chosen by the person who did the experiment. The independent variable changes the result of the dependent variable. In the case of this experiment, the independent variable is the concentration of the solutions (measured in military).
The Independent variable is the range of solutions. Dependent Variables: This is the variable that is affected by the independent variable and changes accordingly. In this experiment, the dependent variables changed according to the sucrose concentration in the solutions. These were: a. The final length b. The final mass c. The observations Non-Variables: These are the figures that if not kept the same would produce unfair results. These would be: a. The initial length b. The amount of solution in each test tube Observations: Hopefully, the observations taken will prove linked and dependent upon the independent variable.
These will change with the mass and length results hat are also dependent variables, yet change could be minimal and not be seen at every change in solution. The Observations are: a. Elf the chips would float or sink b. Ranking the chips from stiff to floppy Below is an example of how the results should be recorded from a previous osmosis experiment: Military affiliation Lengthening aftercare analytical Massing Mischance in Float or Stiff or Glucose (CM)Osmosis (CM)Length (%) (G) (G)mass (%) Sink Floppy 02 or stank 0. “Floats 0. 4″Floats 0. 6″Floats 0. 8″Floats 1 “Floats The change in mass must be recorded as a percentage as the initial mass for each hip is different, in order to make the results more comparable, the same rule should be applied to the change in length. To calculate the % change in mass/length we use this formula: Change in Length/Mass Original Length h/ Mass Conclusion – In both the case of 2 CM and CM chips, as the concentration of the solution went up, the growth in length became more negative.
This does not mean that less change took place, but that the chip that the positive increase in the chips at O Mimic gradually got lower, (with the exception of a few inaccurate readings), until it became a loss in length. For both the CM and CM chips the loss in length happened after 0. 8 Mimic, yet the concentrations used to conduct the experiment were not enough to give us a more accurate concentration at which the concentrations became negative although the line of best fit of both the CM and CM chips would suggest it was a little after 0. Mimic. When the change in length is shown as a percentage, the CM chip had a bigger change between its 0. 0 molar and 1. 0 molar results than the CM chip. CM chip = 10% = 15% change in length CERN chip = 3. 333% + change Yet these results are not very helpful as the changes in length are not accurate and o not give us an accurate measurement such as volume, that would give us more than the length of one side.
The change in length expressed as a percentage is also not helpful as it does not help show the difference between how much water the cell sap vacuole of a CM chip can hold compared to that of a CM chip. In the results, the change in length in centimeters of both the CM and CM chips between the 0. Mecum and 1. Mecum are close: CM chip = 2. CM – 1. CM = 0. CM change CM chip = 3. CM – 2. CM = 0. CM change. If the results were more accurate, the CM chips change in centimeters would be argue than the CM chips because its cell sap vacuole should hold more water in the same concentration.
If the volume of the chips was taken instead of the length and the experiment was conducted accurately, this would be the case. For the length results I am not going to link them to the mass results or observations as they are not accurate, yet a change is still obvious as shown by the graph. This is proof that osmosis did take place and that at a 0. Mecum the potato chips only take in water because they have lower water potentials than the H2O they have been placed