Purpose
The purpose of performing part I of this lab was to study the relationship between surface area/volume with regard to rate of diffusion. We used treated agar blocks to model artificial cells because their surface area and volume could be easily measured, and they visually show the amount of diffusion. By using blocks of different sizes (and with different SA: V ratios, we can compare the rate that diffusion occurred for each block.
Background Information
All molecules are constantly in motion and have kinetic energy. When these molecules are clustered together and have a high concentration in one area, they tend to collide frequently and spread out. Even though individual molecules may be moving in all directions, the net movement of molecules will go from areas of high concentration to areas of low concentration. This spreading out of molecules is called diffusion. Once the molecules have spread out and reached equal concentration in all areas of the system, there is a dynamic equilibrium where the molecules continue to move but there is no net movement. Diffusion also occurs because it increases entropy in the system; when the molecules spread out, they become more disordered, adhering to the 2nd Law of Thermodynamics (entropy increases for all spontaneous processes).
The difference in concentration between two areas forms a concentration gradient; molecules will diffuse down their concentration gradient. This process is a type of passive transport and requires no
Cells and molecules in the environment are constantly moving and changing, for cells to function properly there is a need for equilibrium to be met. The size of the cell and the solution outside of the cell affects the rate of diffusion and osmosis in the cell. Cells are constantly trying to reach an equilibrium with the molecules and substances around it, which is why there are such terms as: hypertonic, hypotonic and isotonic. The procedures allowed testing of whether or not surface area or volume increased diffusion and how different substance control diffusion. Cells are constantly moving to reach equilibrium through diffusion and osmosis.
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.
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
The difference is that along with large molecules, living cells prevent molecules with positive charges and solubility. This is not representing in dialysis tubing, and is only found in living cells because the tubing is only based on molecular size (98). When referring the rate of diffusion, the concentration gradient influences the diffusion rate, based on the factors of temperature. The ability for molecules diffuse from high to low concentrations primarily depends on the concentration gradient between the two areas.(96-99). My hypothesis for the study is that in the hypotonic, hypertonic, and isotonic solutions, the direction and rate of osmosis will determine based on the concentration inside the dialysis tubing. My prediction is that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant.
Diffusion is the movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached. Osmosis, however, is the movement of water according to its own concentration gradient across a selectively
Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration. The rate at which molecules diffuse can be determined by the relationship of molecular weight and that rate of diffusion through a membrane. Hypothesis of this experiment is that the fluid with higher molecular weight will diffuse at a slower rate and distance.
A cell needs to perform diffusion in order to survive. Substances, including water, ions, and molecules that are required for cellular activities, can enter and leave cells by a passive process such as diffusion. Diffusion is random movement of molecules in a net direction from a region of higher concentration to a region of lower concentration order to reach equilibrium. Diffusion does not require any energy input. Diffusion is needed for basic cell functions - for example, in humans, cells obtain oxygen via diffusion from the alveoli of the lungs into the blood and in plants water
Diffusion is an automated process by where the levels of oxygen, water and carbon dioxide pass over a ‘semi-permeable membrane’ between the walls of the cells and blood vessels to create a level environment. This membrane only allows these three elements to pass whilst retaining other elements such as blood cells, hence semi-permeable. The high concentration on one side of the cells transfers through this membrane until the level is equal on both sides.
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
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.
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).
The next experiment was to test diffusion in agar solution. A petri dish with a layer of solidified agar had four holes punched in it using a No. 5 cork borer. Three holes were punched in a triangle shape with the fourth hole directly in the middle. There should be 15 mm between each outside hole and the middle hole. The three outside holes were filled with one drop each of potassium bromide, potassium Terri cyanide, and sodium chloride. The middle hole was filled with a drop of silver nitrate. It is very important to make sure that none of the holes overflow. After each has been filled allow to sit for an hour and observe the results.
2.1. Diffusion is the spontaneous kinetic movement by which molecules move from an area of a high concentration to an area of low concentration. Diffusion continues until it reaches equilibrium. Osmosis is similar to Diffusion but it’s the process in which water moves across a semi-permeable membrane and goes to the higher concentration of solute.1
The process of diffusion occurs in and out of a cell when molecules travel from areas of higher