Dennis M. Feliciano
Grand Canyon University
BIO100L Biology Concepts Lab
June 25, 2011
Osmosis Experiment
Materials
Grapes (unblemished)
Raisins (larger is better)
Water
Salt
Four small containers (i.e., drinking cups or clear glasses)
A metric ruler
Methods and Procedure
Place 1 cup (236 ml) of water in each of the 4 containers.
In 2 of the containers, add 1 tablespoon (14.8 ml) of table salt and mix well.
Measure the length and width of a raisin and place it in 1 of the plain water containers. Measure the length and width of a second raisin and place it in one of the salt water containers.
Measure the length and width of a grape and place it in the second of the plain water containers. Measure the …show more content…
length and width of a second grape and place it in the second of the salt water containers.
After 1 hour, remove and measure the length and width of each piece of fruit and return it to the appropriate container. Note any physical changes in the fruit and describe their appearance.
After 24 hours, remove and measure the length and width of each piece of fruit. Note any physical changes in the fruit and describe their appearance.
Written Lab Report
Introduction
Address the following questions:
Define osmosis. Osmosis is a physical-chemical process associated with the behavior of water as a solvent in a solution to a semipermeable membrane to the solvent (water) but not the solutes. Such behaviour involves a simple diffusion through the membrane of water without expending energy. Osmosis is an important biological phenomenon for cellular physiology of living things.
State a prediction for each experiment (all 4). I predict that the raisin submersed in the fresh water solution will expand and increase in size. The grape submersed in the fresh water solution will not change in size. The raisin submersed in the salt water will absorb water until the water solute level is balanced. The grape submersed in the salt water will shrink because water will be drawn out of the grape.
State the independent variable; state the dependent variable. The independent variable is the concentration of the water solution and the dependent variable is the change (if any) in cell size of each fruit.
What controlled variables were used in this experiment (what stayed the same in all trials)? The length of time submersed in the water solution. The temperature. The amount of water used in each cup. The amount of salt in the salt water solute.
State a hypothesis for the experiment. Hypothesis: The raisins in both the fresh and salt water wil expand in size because the water content inside the raisin is lower than the water outside the cell. The grape in fresh water may not change in size at all because there is water content inside. The grape submersed in the salt water solution will shrink because the solution outisde of the grape is hypotonic so water will flow out of the grape causing it to shrink.
Data Analysis
Present all data in a table. List all data points and calculate the mean length and width for each experiment at the start, after 1 hour, and after 24 hours – raisin/water, raisin/salt water, grape/water, and grape/salt water.
|Raisin/Water |Raisin/Salt Water |Grape/Water |Grape/Salt Water |
|Before Submersion: |Before Submersion: |Before Submersion: |Before Submersion: |
|11cm Wide |11cm Wide |17cm Wide |15cm Wide |
|17cm Long |15cm Long |18cm Long |16cm Long |
|After 1 Hour: |After 1 Hour: |After 1 Hour: |After 1 Hour: |
|9cm Wide |11cm Wide |17cm Wide |15cm Wide |
|15cm Long |15cm Long |18cm Long |16cm Long |
|After 24 hours: |After 24 Hours: |After 24 Hours: |After 24 Hours: |
|11cm Wide |11cm Wide |17cm Wide |15cm Wide |
|17cm Long Swelled but did not |14cm Long Raisin looked darker |18cm Long The grape showed no |16cm Long |
|change in width or length.
The |and the skin ripped but overall|sign of increase in size nor |Grape showed signs of skin |
|raisin became more rounded. |didn't show any increase in |shape |wrinkling but didn't shrink in …show more content…
|
| |width or length. Rounded | |width or length. |
Explain any difficulties or unexpected events and account for any missing data. Results surprised me and differed from actual osmosis process. Why? I have no explanation because nothing in the experiment environment changed.
State which way water moved in each experimental trial. The water moved into the raisin submersed in water. The water moved into the rasin submersed in salt water. There were no signs of any water movement in the grape submersed in water or the grape submersed in salt water.
Discussion
Were your predictions realized? Why or why not? My predictions were somewhat realized. Again, I have no explanation for the results because it contradicted the process of osmosis especially the process of diffusion. It would seem that some molecules were able to pass through the cell. The only explanation would be that there was some salt content in either the raisins or grapes used. The pores may have been obstructed by sugar, in the case of the raisins.
Does your data support or reject your hypothesis? My data somewhat supported my hypothesis. The cell membranes may have been contaminated or in some way obstructed.
If a solution was provided with the exact same solute concentration as found on the inside of the grape/raisin, would you use this solution in the experiment? Why or why not? Would this solution be hypotonic, hypertonic, or isotonic in the context of this experiment? What do you predict would happen if you used this solution in 1 of your experimental trials? No, I wouldn't use the solution because it would be considered an isotonic solution which is expected to have no results or effect on the fruit. It would make for a balanced environment and therefore show no change in cell size or characteristics. If the raisins were submersed in a raisin juice there may be a possibility that the raisins would turn to sludge.
Is osmosis a passive or active cellular process? Explain.
Osmosis is a passive celluar process because there is no expenditure of energy during this process.
Can you propose an additional experimental design to test your hypothesis or suggest further studies that might be done? Osmosis Experiment using eggs, water and corn syrup. “Movement Across an Egg Cell Membrane” by Dr. Robert Pope and Professor Miriam del Campo of the Biology Health and Wellness Department at the Kendall Campus of Miami Dade College
Implications or Significance of Data Results
Red blood cells (RBCs) have an internal solute concentration of 0.9 %. Plasma is isotonic in relationship to RBCs. What would you guess is the solute concentration of plasma? Why? The solute concentration would be 0.9% because it is isotonic in relationship to the RBCs. Isotonic meaning same solute concentration.
What would you guess is the solute concentration of intravenous fluid (IV fluid)? Why? I would have to guess it is the same solute concentration as the blood it is being introduced or less so as to not create any physiological damamge.
What would happen to a patient’s RBCs if the nurse accidently put plain water in the IV line? Why?
Nothing. Our body is made up of mostly water so it wouln't have any adverse affects to our system. It would be like drinking water.
Explain, in approximately 2-3 paragraphs, how the human kidney uses osmosis to achieve osmoregulation. Include the hormones involved and explain what part they play. Include a brief discussion of homeostasis and negative feedback.
The human kidneys are physiological filters that removes toxins through osmoregualtion.
There are a pair of kidneys that are 1% of the weight or account for 25% of cardiac output. They spend a large amount of blood and they represent a 20 to 25% of cardiac output they control the concentration of most of the constituents of the body fluids and excrete the end products of metabolism. All living things, whether aquatic or terrestrial, are required to osmoregulation or osmotic pressure regulation. Many of them have managed to survive at hipotónicos or hipertónicos means by physical or chemical mechanisms to avoid changes of osmotic presión in their domestic environment. Kidneys through osmoregulation absorb large amounts of water to filter blood continually, but contouring tubes and the loop of Henle reabsorbe virtually all the water and a variable amount of
salts. Osmoregulation is the process by which the body maintains homeostasis of body fluids, which prevents them from diluting or concentrating too much. Osmoregulation is nothing more than the regulation of water into the human body, and performs this action by several mechanisms, mostly related to heart and kidney organs. A hormone that is involved in the regulation of water balance is inappropriate antidiuretic hormone (ADH). It is produced in a part of the brain called hypothalamus and is stored and secreted by the pituitary gland. Osmoreceptor cells in the hypothalamus monitor the osmolarity of the blood and when it gets to a level about 300mosm/lt (i.e. loss of water through sweating a lot), more ADH is released into the bloodstream through a negative feedback loop process and reaches the kidneys to create balance. This hormone has the effect of increasing epithelial permeability to water. This amplifies the reabsorption of water and reduces the volume of urine. On the other hand, if a high volume of water reduces the osmolarity to a level below that established, little ADH is released. This reduces the reabsorption of water and increases the amount of diluted urine.
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GCU style is not required, but solid writing skill is expected.
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