Diffusion Osmosis Lab Report

Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration. The diffusion of water molecules through a semi-permeable(selectively permeable) membrane is osmosis. Semi-permeable means that some molecules can move through the membrane while others can not. Diffusion and Osmosis are passive forms of transport requiring no energy. Active Transport utilizes energy in the form of ATP. Water is a solvent that can dissolve a number of substances more than any other substance. Wherever water goes, through the ground or a body, it takes along valuable molecules. Water’s chemical composition causes it to be attracted to many different molecules and be attracted so strongly it disrupts the forces and dissolves it. Water can pass through the semipermeable membrane without any help but can change the solution, on the other side of the cell membrane, depending on how much it diffuses in and out.

Next, I poured distilled water just below the 250ml mark on the neck of the volumetric flask.

2. Explain your observations in detail in terms of concentration gradient, diffusion, osmosis, osmotic pressure, passive transport, and active transport.

In conclusion, the potato cube with the highest surface area to volume ratio (the 1x1x1 cube) had the fastest rate of diffusion as it had the largest percentage increase in mass. While all the other cubes of potato had larger increases in mass at face value compared to the smallest cube, the smallest cube had the largest overall gain in percentage. The results support my hypothesis that the smallest cube will have a higher rate of osmosis because it has a proportionally larger amount of surface area compared to its volume.

The dialysis tubing will be clamped at one end in order to fill it and then clamped at the other end to seal the filled bag. If the bag is not soft and floppy, the experiment will not work. Blot a bag with a paper towel to absorb the moisture and weigh it, if this blotting process is not done it could interfere with the weight readings creating inaccurate information. After the bags of the solutions are prepared, they will be placed into five different beakers with different solutions. Beakers 1-4 will be filled with tap water and the fifth beaker is filled with 40% sucrose and water. Fill each beaker with just enough water or solution so that the bag is covered and place the bags in the beakers simultaneously and record each time. Every 10 min the bags are to be taken out, blotted, and weighed again before returning them back into their respective beaker for another 10 min. The process is repeated until you have reached 90 min. The weights should be recorded in grams (g).

All cells contain membranes that are selectively permeable, allowing certain things to pass into and leave out of the cell. The process in which molecules of a substance move from an area of high concentration to areas of low concentration is called Diffusion. Whereas Osmosis is the process in which water crosses membranes from regions of high water concentration to areas with low water concentration. While molecules in diffusion move down a concentration gradient, molecules during osmosis both move down a concentration gradient as well as across it. Both diffusion, and osmosis are types of passive transport, which do not require help.

Cells are always in motion, energy of motion known as kinetic energy. This kinetic energy causes the membranes in motion to bump into each other, causing the membranes to move in another direction – a direction from a higher concentration of the solution to a lower one. Membranes moving around leads to diffusion and osmosis. Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration, until they are equally distributed (Mader & Windelspecht, 2012, p. 50). Cells have a plasma membrane that separates the internal cell from the exterior environment. The plasma membrane is selectively permeable which allows certain solvents to pass through

The diffusion across a cell membrane is a process of passive and spontaneous net movement of small lipophilic molecules. The molecules move from a high concentration to a low concentrated region along the concentration gradient. The result being a point of equilibrium, this is where a random molecular motion continues but there is no longer any net movement. However, there are things that can affect the rate of diffusion, these being temperature, surface area, concentration, size of the molecule, permeability, diffusion distance and concentration difference. Osmosis is a type of diffusion as it is the movement of water molecules through a semipermeable membrane into a region of higher solute concentration. Equilibrium is reached when the solute concentration is equal on both sides. Water potential is measured in kiloPascals, it is the measuring of the concentration of free water molecules that are able to diffuse compared to pure water, which is 0 kilopascals. It is a measure of the tendency of free water molecules to diffuse from one place to another. The result being, the more free water molecules, the higher the Water Potential. However, Water potential is affected by two factors: pressure and the amount of solute.

A concentration gradient is a gradual change in solute concentration between two areas, these areas are usually separated by a membrane. A gradient result from an unequal distribution across the cell membrane. When this happens, the solutes travel along the concentration gradient (Seeley, Stephens, Tate, 2005). This type of movement is called diffusion. Diffusion is the tendency of molecules to move from a higher concentrated environment to a lower concentrated environment. This movement continues until both sides are even. Diffusion across a cell membrane is a type of passive transport, a transport that does not require energy (Karp, 2010).

As we can see in Figure’s 1.2 and 1.3, when there was no sucrose solution, the potato increased in weight. This is due to the fact that the sucrose solution was hypertonic in comparison to the potato slice. Through osmosis, the solution moved along the concentration gradient and into the potato slice making it hypotonic. When there were higher concentrations of sucrose solution, the potato decreased in weight. This is due to the fact that the potato was hypertonic in comparison to the potato. Through osmosis, sucrose from the potato moved along the concentration gradient out and into

diffusion is one of the passive transport processes. it is used in oxygen entering a cell and carbon dioxide leaving a cell. diffusion is the movement of particles such as atoms or molecules from a high concentration place in an area of a low concentration. this shows that they diffuse down the concentration gradient. the concentration gradient is a gradual change in the concentration of solutes in a solution as a function of distance through a solution. in biology a gradient results from an unequal distribution of particles across the cell membrane. When this happens solutes move along the concentration gradient until the concentration of the

4.Measure 35mL of warm water and add them into each of the 4 test tubes at about roughly the same time. It is essential that the water is warm. Do not seal the test tube.

Purpose: The purpose of this lab is to familiarize you with osmosis and, specifically, what happens to cells when they are exposed to solutions of differing tonicities.

Either the solution is hypotonic which means that the solution has a lower concentration than the potato core and this would cause water to flow into the potato and make it larger and therefore increase its mass. The state the cell is in is called turgid.

This would happen by using similar sizes and lengths of potato cylinders and applying the into different concentrations of sucrose (0,10%,30%, 50%, 70%) in foam cups then measuring the change in mass of the potato cylinders afterwards. Maintaining all variables unchanged such as pH, same size, covered solutions, and a constant temperature. The time taken for all potato cylinders will be 24 hours.