# Biology Osmosis Experiment

Osmosis Experiment Diana Arrowood Grand Canyon University BIO-100L Biology Concepts September 16, 2011 Osmosis Experiment Directions Use the information below to complete the Osmosis Experiment. Materials 1 fresh baking potato Water Salt Four small containers (i. e. , drinking cups or clear glasses) A metric ruler Methods and Procedure 1) 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 until dissolved. Label which containers have salt. Cut a fresh baking potato into 5 mm slices.

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Cut four rectangles 2. 5 cm x 1 cm from the slices as close to the same size as possible. Measure the length and width of each rectangle in metric units and place one in each of the containers, keeping track of which measured slice went in which container. There will be two slices (duplicates) for fresh water and two for salt water. After 1 hour, remove and measure the length and width of each piece of potato and return it to the appropriate container. Note any physical changes. After 24 hours, remove and measure the length and width of each piece of potato.

Note any physical changes in the potatoes and describe their appearance. Written Lab Report Introduction 1) Address the following questions: A) Define osmosis. Osmosis is the movement of solvent molecules through a selectively permeable membrane into a region of higher solute concentration, aiming to equalize the solute concentrations on the two sides. [1][2][3] It may also be used to describe a physical process in which any solvent moves, without input of energy,[4] across a semi permeable membrane (permeable to the solvent, but not the solute) separating two solutions of different oncentrations. [5] Although osmosis does not create energy, it does release kinetic energy [6] and can be made to do work, [7] but is a passive process, like diffusion. (en. wikipedia) (2011-09-16) Osmosis is the passage of water from a region of high water concentration through a semi-permeable membrane to a region of low water concentration. (Purchon) (n. d. ) 1. Semi-permeable membranes are very thin layers of material (cell membranes are semi-permeable) which allow some things to pass through them but prevent other things from passing through.

Cell membranes will allow small molecules like Oxygen, water, Carbon Dioxide, Ammonia, Glucose, amino-acids, etc. to pass through. Cell membranes will not allow larger molecules like Sucrose, Starch, protein, etc. to pass through. 2. A region of high concentration of water is either a very dilute solution of something like sucrose or pure water. In each case there is a lot of water: there is a high concentration of water. Some teachers use the definition which starts “Osmosis is the passage of water from a dilute solution to a…… ” this means exactly the same as the definition I have given. 3.

A region of low concentration of water is a concentrated solution of something like sucrose. In this case there is much less water. (Purchon)(n. d. ) * b) State a prediction for each experiment (both salt and fresh water). * * To find out what the solute concentration of a potato is, I will find out the effect of Osmosis on a potato. If there is more water outside the potato than inside of the potato, the potato will increase in size. If there is less water outside of the potato than inside the potato, the potato will decrease in size. (Purchon) (n. d. ) * How will the potato change when adding salt to the water? Water that has different concentrations will have an affects on the potato when it is placed into the water. Potato cells have water in them, giving them the ability of Osmosis * * Hypertonic- The concentration of water is higher inside the cell than outside the cell, more water will be flowing out of the cell than into the cell. * Hypotonic- The concentration of water is higher outside the cell than inside of the cell, more water will be flowing into the cell than out of the cell. – * Isotonic- The water concentration inside of the cell and outside of the cell will be equal. The water will move in and out at the same rate. Salt- Chloride and Sodium are the two major components. Sodium and chloride are needed by all living creatures. Salt is involved in regulating the water content in our bodies. * Osmoregulation- When a plant cell becomes immersed in an isotonic the plants tissue becomes flaccid and droopy and will eventually wilt. I predict that the potatoes in the salt water will decrease in size. I predict the potatoes in tap water will increase in size. | * * c)State a hypothesis for the experiment. This should explain why you made the predictions you made above. What is the underlying principle that leads logically to these predictions? When a potato is placed in a salt solution it will increase in size because the potato is hypertonic to the solution. * When a potato is placed in fresh water it will also go through Osmosis. The cell membrane of the potato is called a semi permeable membrane. When you have a concentrated solution that is separated from a less concentrated solution by a semi permeable membrane, the liquid will flow into the more concentrated solution. * * d)State the independent variable; state the dependent variable. * Variables: * Independent- The water with salt and the water without salt. * Dependent- The potato slices. * e)What controlled variables were used in this experiment (what stayed the same in all trials)? * Controlled variables- The size of the potatoes were cut to equal size. Each bowl has exactly one cup of water. Data Analysis 1) Present all data in a table. List all data points, the length and width for each experiment at the start, after 1 hour, and after 24 hours – two slices in plain water and two slices in salt water. Explain any difficulties or unexpected events and account for any missing data. * * * * I measured four bowls with exactly 1c. Water * I cut the potato into 4 equal pieces measuring 2. x 1 cm. * I placed 1 TBSP of salt into 2 bowls and placed a slice of potato into each bowl. * I placed the remaining two slices into individual bowls with 1 cup fresh water. * * * Salt water Fresh water * * * * * After one hour I noticed the discoloring of the potato, and they were limp and soft, in the salt water. * I measure the salt water pieces at 1. 5 x . 08 * After one hour I notice the potato pieces in the fresh water was crisp and firm. * After one hour I measure the fresh water potato pieces at 3. cm. X 1. 5 cm. The potatoes are made up of cells which contain water. The potatoes in the salt water went limp because some of their water was sucked out by the salt in the water. The membranes inside the cell walls in the potato have very tiny holes in them. These tiny holes allow water to go through but not the salt. * The salt will move around and block the holes, and then the water can’t get through to the inside of the cell. The results are that with time the number of water molecules going from the inside of the cell to the outside of the cell is greater than the number going from the outside of the cell to the inside.

They lose water and go limp. This is Osmosis. * By placing the potatoes in fresh water, the cell walls have an equal flow of water. The water molecules went through in both directions. * * * I measure fresh water slices after 24 hours. 3. cm x 1. 5cm. * I measure salt water slices and they measure 1. 5 cm. x . 08cm. * After twenty-four hours I was surprised to find my measurement had not altered much since the previous measurement. It allows me to see that Osmosis occurs in an hour with a potato. * State which way water flowed (into or out of each piece of potato) in each experimental trial. In fresh water the potato tubes swell, because water enters their cells by Osmosis. * * Discussion 1) Were your predictions realized? Why or why not? * Yes. I predicted my experiment upon the research of Osmosis. 2) Does your data support or reject your hypothesis? * My data supports my hypothesis. * * * * * * If a solution was provided with the exact same solute concentration as found on the inside of the potato, would you use this solution in the experiment? Yes. Why or why not? * The liquid inside of the potato is slightly salty. So the potato in the fresh water would actually absorb some water from the bowl.

The cell wall stops the flimsy membrane from swelling up and bursting. * Would this solution be hypotonic, hypertonic, or isotonic in the context of this experiment? * Isotonic. * What do you predict would happen if you used this solution in 1 of your experimental trials? * Isotonic- The water concentration inside of the cell and outside of the cell will be equal. The water will move in and out at the same rate. * I think it would stay the same. * 1) Is osmosis a passive or active cellular process? * Passive- Passive transport is the cellular process of moving molecules and other substances across membranes.

Passive transport relies on innate permeability of the cell membrane and its component proteins and lipids. * There are four kinds of passive transport. Diffusion, Facilitated Diffusion, Osmosis, and Filtration. * * Can you propose an additional experimental design to test your hypothesis or suggest further studies that might be done? * * I am curious if the water were hot if it would make a difference. Implications or Significance of Data Results 1) 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? 0. 9% * Why? * Isotonic means- The solute to solvent ratio inside of the cell and outside of the cell will be equal. 2) What would you guess is the solute concentration of intravenous fluid (IV fluid)? * 0. 9% * Why? * It is close to the concentration in the blood. Most IV fluids used have the same tonicity of blood to keep from getting fluid overload or third spacing, or hypertonicity. What would happen to a patient’s RBCs if the nurse accidently put plain water in the IV line? * Free water is water has no organic or inorganic ions. Hypernatremia is the result from a deficit of free water.

This lack of water can be replaced orally, but, should never be given through an IV. Without having additives to increase osmolarity, hemolysis (destruction of the RBC) will occur. * Why? * Normal saline (0. 9%) has the same osmotic pressure as human blood. Sterile water for injection has zero osmotic pressure. It is suppose to be used in small quantities to dissolve or dilute drugs or electrolytes by creating the necessary osmotic pressure to make the solutions safe for IV administration. * Explain, in approximately 2-3 paragraphs, how the human kidney uses osmosis to achieve osmoregulation.

Osmoregulation- The physiological process that an organism uses to maintain water balance. Osmoregulation compensates for water loss, excessive water gain, and maintains osmolarity . Osmoregulation Osmoregulation is the active regulation of the osmotic pressure of bodily fluids to maintain the homeostasis of the body’s water content; that is it keeps the body’s fluids from becoming too dilute or too concentrated. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher the osmotic pressure of a solution the more water wants to go into the solution.

The kidneys are used to remove excess ions from the blood, thus affecting the osmotic pressure. These are then expelled as urine. (Wikipedia) (n. d. ) Osmoregulation is the control of the levels of water and mineral salts in the blood. It is a homeostatic mechanism. There are three important homeostatic mechanisms: osmoregulation, thermoregulation and regulation of blood sugar levels. Homeostasis is important because it results in our cells being bathed in tissue fluid which has the correct amount of water, mineral salts, glucose and temperature. There are no carrier proteins in water so it cannot be transported across cell membranes.

It can pass directly through membranes in a response to changes in ion concentration. Water movement is controlled indirectly by pumping ions such as sodium and potassium across cell membranes, this creates a concentration gradient that causes water to flow by osmosis. If sodium is excreted from the body water tends to follow it. The rate of water loss is regulated by hormones that control the rate of sodium excretion or the water permeability of the excretory ducts. * Osmoregulation is usually achieved by excretory organs that serve for the disposal of wastes.

Urination is mechanism of both waste excretion and osmoregulation. Kidneys are vertebrate osmoregulatory organs in which blood pressure forces fluid to filter through the walls of the blood capillaries into tubules that process the filtrate into urine. Each kidney has 1. 2 million tiny balls of capillaries called glomeruli, where the blood pressure is very high. A filtrate of the blood plasma, free of cells and protein, seeps from these capillaries into a hollow ball called a glomerular capsule. From there, it flows into a series of tubules that remove most of the salt nd water along with useful material such as glucose and vitamins, while secreting hydrogen and potassium ions, urea, and drugs (for example, penicillin and aspirin) into the tubular fluid. A final tube in the pathway, called the collecting duct, adjusts the salinity of the urine by reabsorbing variable amounts of water, before the urine leaves the kidney for storage in the urinary bladder and eventual elimination from the body. Two hormones, aldosterone and antidiuretic hormone, regulate the amounts of salt and water reabsorbed, enabling the human kidney to adjust water loss or retention to the body’s state of hydration.

Human blood plasma and tissue fluid normally has an osmolarity of 300 milliosmoles per liter (mOsm/L); that is, 0. 3 mole of dissolved particles per liter of solution. Human urine can be as dilute (hypoosmotic) as 50 mOsm/L when the body is voiding excess water, or as concentrated (hyperosmotic) as 1,200 mOsm/L when conserving water. * Include the hormones involved and explain what part they play. Include a brief discussion of homeostasis and negative feedback. Kidneys play a very large role in human osmoregulation, regulating the amount of water in urine waste.

With the help of hormones such as antidiuretic hormone, aldosterone and angiotensin II, the human body can increase the permeability of the collecting ducts in the kidney to reabsorb water and prevent it from being excreted. Arginine vasopressin (AVP), also known as antidiuretic hormone (ADH), is a neurohypophysial hormone found in most mammals, including humans Vasopressin is a peptide hormone that controls the reabsorption of molecules in the tubules of the kidneys by affecting the tissue’s permeability.

It also increases peripheral vascular resistance which in turn increases arterial blood pressure. It plays a key role in homeostasis, and the regulation of water, glucose, and salts in the blood. It is derived from a preprohormone precursor that is synthesized in the hypothalamus and stored in vesicles at the posterior pituitary. Most of it is stored in the posterior pituitary to be released into the bloodstream; however, some AVP is also released directly into the brain where it plays an important role in social behavior and bonding.

Aldosterone is a hormone that increases the reabsorption of sodium ions and water and the release (secretion) of potassium ions in the collecting ducts and distal convoluted tubule of the kidneys’ functional unit, the nephron. This increases blood volume and, therefore, increases blood pressure. Drugs that interfere with the secretion or action of aldosterone are in use as antihypertensives. One example is spironolactone, which lowers blood pressure by blocking the aldosterone receptor. Aldosterone is part of the renin-angiotensin system.

Aldosterone is a yellow steroid hormone (mineralocorticoid family) produced by the outer-section (zona glomerulosa). of the adrenal cortex in the adrenal gland and acts on the distal tubules and collecting ducts of the nephron, the functioning unit of the kidney to cause the conservation of sodium secretion of potassium, increased water retention, and increased blood pressure. The overall effect of aldosterone is to increase reabsorption of ions and water in the kidney. Angiotensin, a peptide hormone causes blood vessels to constrict, and drives blood pressure up.

It is part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure. Angiotensin also stimulates the release of aldosterone another hormone, from the adrenal cortex. Aldosterone promotes sodium retention in the distal nephron, in the kidney, which also drives blood pressure up. Angiotensin is an oligopeptide in the blood that causes vasoconstriction increased blood pressure and release of aldosterone from the adrenal cortex. It is a hormone and a powerful dipsogen. It is derived from the precursor molecule angiotensinogen, a serum globulin produced in the liver.

It plays an important role in the renin-angiotensin system. Angiotensin was independently isolated in Indianapolis and Argentina in the late 1930s (as ‘Angiotonin’ and ‘Hypertension’ respectively) and subsequently characterized and synthesized by groups at the Cleveland Clinic and Ciba laboratories in Basel, Switzerland. (Angiotensin) (n. d. ) * Include a brief discussion of homeostasis and negative feedback. * Homeostasis is the regulation of everything in a properties internal environment. Working with a multitude of tasks to keep balance and all systems running in a normal range. GCU style is not required, but solid writing skill is expected. * * * * * * * * * * * * * * * * * * * * * * * * * * * References en. wikipedia. org/wiki/Angiotensin_II#Angiotensin_II Retrieved September 18, 2011 from http://en. wikipedia. org/wiki/Angiotensin_II#Angiotensin_II en. wikipedia. org/wiki/Human_homeostasis Retrieved September 16, 2011 from http://en. wikipedia. org/wiki/Human_homeostasis * en. wikipedia. rg/wiki/Osmosis#Basic_Retrieved September 16, 2011 from * * http://en. wikipedia. org/wiki/Osmosis#Basic_explanations * * faculty. clintoncc. suny. edu/faculty/Michael. Gregory/files/Bio%20101/Bio%20101%20Laboratory/Cells/cells. htm#Potato Retrieved September 16, 2011 from * * http://faculty. clintoncc. suny. edu/faculty/Michael. Gregory/files/Bio%20101/Bio%20101%20Laboratory/Cells/cells. htm#Potato * * purchon. com/biology/osmosis. htm Retrieved September 16, 2011 from * * http://purchon. com/biology/osmosis. htm * * © 2010. Grand Canyon University. All Rights Reserved.

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