When a substance is released into an area, the random movement of its molecules results in a multitude of collisions. These collisions, in turn, lead to a dispersion of the molecules. The overall movement of the molecules will be from an area of high concentration, where there will be more collisions, to areas of low concentration, where the number of collisions will be much less. This process of dispersion will continue until there is no net gain or loss of molecules in an area. The process by which this equilibrium occurs is called diffusion. Diffusion is vitally important to biology on many levels; individual cells, organelles, and even whole organisms rely on diffusion to carry out the processes essential to life. One especially important aspect of diffusion is osmosis, or the diffusion of water. This often occurs across a semi-permeable membrane…
active transport: the movement of molecules across a membrane that requires the expenditure of cellular…
1. The cell membrane regulates and controls what kind of molecules ______ move in & out of the cell.…
2. Purpose: The purpose of this lab is to help give visual understanding of diffusion which is a solution of high concentration spontaneously (no energy required) moving to an area of low concentration. Also taking a look at osmosis, which is the movement of chemicals across the cell membrane. Osmosis requires some type of energy to be put in for this to happen. After these experiments we should have a better idea and visualization of how chemicals transfer across the cell membrane.…
Purpose: The purpose of this activity is to determine the effects of a selectively permeable membrane on diffusion and osmosis between two solutions separated by a membrane.…
Diffusion is the molecular net movement from a higher concentration to a lower concentration. For instance, when a person is smoking, the smoke diffuses into the air. The molecules in the smoke, released from the cigarette, travel through the air. Here is how it occurs. When molecules are close enough, they collide with each other, their kinetic energy changes. Due to the direct relationship between diffusion and molecular kinetic energy, the molecules move away from the point of the collision as their kinetic energy is redirected. Therefore, molecules always tend to distribute themselves throughout the area they stay. It continues until dynamic equilibrium is reached, that is, no net movement happens. Molecules at that time are still in motion, but the amount of molecules moving in one direction equals to the amount of molecules moving in the other direction.…
This experiment demonstrates the process of osmosis because when the egg is placed in the water, it gets slightly larger due to the different…
Change the objective lens for a higher magnification on your sample (x10, x40, x1000) as to make out things such as its nucleus.…
The molecular composition of the plasma membrane allows it to be selective about what passes through it. It allows nutrients and appropriate amounts of ions to enter the cell and keeps out undesirable substances. For that reason, we say the plasma membrane is selectively permeable. Valuable cell proteins and other substances are kept within the cell, and metabolic wastes pass to the exterior. Transport through the plasma membrane occurs in two basic ways: either passively or actively. In passive processes, the transport process is driven by concentration or pressure differences (gradients) between the interior and exterior of the cell. In active processes, the cell provides energy (ATP) to power the transport. Two key passive processes of membrane transport are diffusion and filtration. Diffusion is an important transport process for every cell in the body. Simple…
The purpose of this lab was to observe the rate of osmosis and diffusion, as well as the effect of molecular size of the particles on this rate. Part I of the lab was a demonstration of osmosis and diffusion, that dealt with raisins in different liquid environments, each with a different concentration of sugar. Part IV of the lab was using the same idea as the demonstration, by putting objects in different concentrations of a substance; in this case elodea leaves in salt water. In both cases, the objects in a greater concentration of the substance were stripped of their water. However, where there was a little or no concentration of sugar or salt, the objects did not lose their water, and in the case of the raisin, became saturated with excess…
Kinetic energy, a root of energy stored in cells, causes molecules to hit into each other and move in new directions. Diffusion is the result of this contact. Diffusion is the random movement of molecules to an area of lower concentration from an area of higher concentration. Osmosis is a type of diffusion. This is the diffusion of water through a selectively permeable membrane from a region of higher water potential to a region of lower water likely. Water potential is the measure of free energy of water in a solution. A living system also contains an active transport to make movement of particles like ions that move against their concentration gradient. The energy source ATP is used during this process to move the particles across the cell membrane. This experiment takes place to measure the diffusion of small molecules through dialysis tubing. This tubing acts as a selectively permeable membrane, allowing larger molecules to pass through, but slowly. Dialysis is the movement of a solute through a selectively permeable membrane.…
This lab focuses on the understanding of osmosis and diffusion in a practical sense. It allows the conductor to see what factors affect diffusion and osmosis. This report was written to explain and present the results gathered in a precise and organized manner. This experiment was divided into two parts. The first part concentrated on the placing potato cylinders in different sucrose concentrations for a period of time. This part was conducted to see if the potato cylinders would gain weight or lose weight because of osmosis. The second part was conducted to see if a dialysis bag, filled with sodium sulfate and starch solution and placed in an albumin/glucose solution, would contain albumin/glucose from the outside or the albumin/glucose solution would contain any sodium sulfate/starch from the inside. The first part of this experiment there is a relationship between the amount of sucrose concentration and final mass. As the sucrose concentration increased the mass of the potatoes decreased. This is a result of the sucrose molecules not being small enough to pass into the membrane of the potato cylinders, but the water was able to change to a different concentration gradient. As the sucrose amount increased the free water molecules decreased, which as a result did not allow the water molecules to enter the potato cylinders. On the contrary, no diffusion of solutes occurred in part two of this experiment. Osmosis, on the other hand, did occur. Water moved into the dialysis bag, thus increasing the bag’s weight. Diffusion did not occur because of the size of the pores in the dialysis bag. The solute molecules were too…
Osmosis is the diffusion of a solvent across a selectively permeable membrane that occurs in response to differences in solute concentrations (Allen and Harper 2014).Osmosis can fall under the category of passive transport which does not require energy. With osmosis being a type of diffusion it is viewed as molecules moving from a high concentration to a low concentration. To further explain if there is a low water concentration, high amounts of solutes will be present. Water will most likely move to areas where the solute concentration is high, which demonstrates why there would be less water concentration.…
In the initial set up of this experiment I had 2 sets of 3 screw-cap test tubes that had each been half-filled with 5% gelatin and 1-mL of the correct dye (either potassium dichromate, aniline blue, or Janus green) in each of the test tubes. I labeled the 3 test tubes of set 1 with which die they contained and marked them “5 ˚C”. Then with the other set I did the same exact thing, except I labeled these test tubes “Room Temperature”. I then placed set 1 of the test tubes in a 5˚ C refrigerator, while I kept set 2 at room temperature for a certain amount of time. I made sure to record the time I began the experiment in my lab manual. To begin, I removed set 1 from the refrigerator and compared the distance the dye had diffused in each of the 3 test tubes with the corresponding test tubes of set 2 that had been kept at room temperature. Next, I held each tube vertically in front of a white sheet of paper, and then used a metric meter to measure how far the dye had diffused from the gelatin’s surface (in millimeters). I then recorded each of these distances in my lab manual. I repeated this step for each of the test tubes in both set 1 and set 2 and recorded my results. Then, using my results, I calculated the rate of diffusion for each dye by using this formula: rate of diffusion = distance/ elapsed time (hours). Each of these calculations was then also recorded in my lab manual. I made sure I noted the time the experiment started, ended, and the total elapsed time in hours in my lab manual as well.…
mass of the potatoes got lower, but the graph did not end up as a…