Aim: The aim of this experiment is to investigate the movement of water into and out of plant cells by osmosis. The cells chosen for study will be taken from potato tubes as they provide a ready supply of homogeneous material.
I did the investigation in two parts, the first part of my investigation was my preliminary investigation and then I did my official investigation. In both of my investigations there are several similarities, such as fair testing, variables, key variables, reliability of evidence and safety precautions. In both of my investigation there were obviously some differences which were in the method, apparatus, results and means of measuring etc.
Essential Background Reading
Osmosis is the diffusion of water molecules across a partially permeable membrane from a high concentration of water to a low concentration of water.
Movement of substances takes place through the cell membrane, which separates the different substances in the cell from its surroundings. This type of membrane allows small molecules such as water to pass through it, but it denies entry to large particles to pass. This membrane is called a partially permeable membrane. The amount of water inside a cell is called water potential.
Turgor is the name given when osmosis takes place between the cytoplasm and the solution outside the cell. This happens when a plant cell is placed in a high concentrated solution of water, water then passes through the cell wall, the cell membrane, and the cytoplasm and into the vacuole. The increased pressure of water inside the vacuole is called Turgor pressure. Then the cell becomes turgid.
Plasmolysis is the opposite of turgor. This happens when plant cells may be placed in a less concentrated solution of water, although this is very unlikely to happen in nature. Water passes out of the vacuole, the cytoplasm, the cell membrane and the cell wall and into the solution outside the cell. The pressure of the vacuole on the cytoplasm decreases until the cytoplasm pulls away from the cell wall.
Diagrams
I have illustrated the diagrams of turgor and Plasmolysis on a separate page.
Fair Testing
This is when the result is only related to the variable being tested.
For e.g. if there are six variables, five variables must be kept identically the same and only one is changed/tested to see how this affects the outcome. This is ensuring that this investigation shall only be testing one variable (Key Variable).
When the cell has all the water it can take inside of it the osmosis
-The cells in the body will increase because osmosis causes molecules to move from a less concentrated solution to a more concentrated solution.
osmosis, it can works both ways so that it can pass into and out of
Diffusion and osmosis are necessary for the efficient transport of substances in and out of living cells. Diffusion is the most common and effective transportation process between cells and their surroundings, the movement of a substance along a concentration gradient from high to low, allowing essential nutrients and compounds to be transported without expending energy. Osmosis is a special kind of diffusion, specific to water. In order to observe diffusion and osmosis in real and artificial cells, a series of experiments was put together to observe how the surface area to volume ratio effects the rates of diffusion by using agar in different shapes with different ratios, next the rate of diffusion due to tonicity was observed using different solutions with different tonicities. And lastly live plant cells were submerged in different solutions with varying water potentials to observe how was potential effects the rate of osmosis and diffusion. It was concluded that the larger surface area to volume ratio, the faster rate of diffusion, the hypertonic solutions caused water to leave a cell and the hypotonic solutions allowed water to enter a cell, and that water potential will move from high to low in an attempt to maintain equilibrium.
The purpose of the Tonicity lab was to help identify the effects of an isotonic, hypertonic, and hypotonic solution to a slice of potato. The difference between diffusion and osmosis is that diffusion is the movement of particles or molecules from a region of higher concentration to a region of a lower concentration. While osmosis consists of the movement of water molecules through a semipermeable from a region of high water concentration to the region of less water concentration (Major Differences). Tonicity is the ability of a solution to ?alter the internal water volume of a cell? (Difference Between Solution, 2013). An isotonic solution should keep their normal shape; the osmotic pressure outside the cell has the same pressure within the cell. A hypotonic solution, are more dilute and contain a lower concentration of nonpenetrating solutes than cells. In contrast, a hypertonic solution have a higher concentration of
Osmosis is a special case of diffusion. It is when the passage of water from a dilute solution moves through a semi-permeable membrane to a more concentrated solution. Selective permeability is whether solutes can cross through a membrane freely or not at all. Plant cells and animal cells differ in that plant cells have a strong cell wall and animal cells do not have cell walls. They both can undergo osmosis and both lose water, however the cell wall of plant cells prevent the cells from bursting whereas animal cells will burst because they have no cell wall.
molecules go in and out of the cell. There is no net movement of water
Going into details of the article, I realized that the necessary information needed to evaluate the experimental procedures were not included. However, when conducting an experiment, the independent and dependent variable are to be studied before giving a final conclusion.
Osmosis is the movement of water molecules across a partially permeable membrane from a region of high water concentration to a region of low water concentration. Osmosis is used to transfer water between different parts of plants. Osmosis is vitally important to plants. Plants gain...
there would be no flow of water into or out of the cell so the cell
Diffusion is when any molecule moves from high to low concentration. Molecules will spread until they have equilibrium. Diffusion equilibrium is reached when the concentration gradient reaches zero. In the lab that we did in class was diffusion. We used iodine and starch. We put starch in the plastic tube and tied it making sure there was no starch on the edges. Then we put iodine in the water and put the starch in the iodine. We kept it for a while. The iodine went in the starch making the water clear and the starch to turn from white to dark brown. This shows diffusion because it shows how the iodine went from high concentration to low concentration. A real life example of diffusion is when you spray perfume in one corner of a room, the molecules of the spray will move around the room. That’s
Activity 3: Investigating Osmosis and Diffusion Through Nonliving Membranes. In this activity, through the use of dialysis sacs and varying concentrations of solutions, the movement of water and solutes will be observed through a semipermeable membrane. The gradients at which the solutes NaCl and glucose diffuse is unproportional to any other molecule, therefore they will proceed down their own gradients. However, the same is not true for water, whose concentration gradient is affected by solute ...
If a plant cell is places in a hypotonic solution the cell has a lower water concentration to that of the solution. Water will move into the cell by osmosis from a high water concentration outside the cell to a lower water concentration inside the cell through a selectively permeable membrane. The cell becomes turbid
Diffusion and osmosis refer to passive transport systems where molecules and ions move down concentration gradients driven by thermal motion. The concentration gradients are setup in solutions in living systems that are separated by biological membranes. Diffusion refers to the spontaneous movement of particles, molecules, or ions from an area of higher concentration to an area of lower concentration. The process occurs slowly without any expenditure of energy. Diffusion occurs in liquids and gases. An example of diffusion is the movement of the smell of a spray from the point of spraying to the rest of the room. On the other hand, osmosis refers to the movement of molecules of a solvent such as water from an area of low concentration to an area of higher concentration. It is a special type of diffusion that occurs in reverse. An example of osmosis is the process through which animal cells feed on the food they partake. Thus, diffusion and osmosis are called passive transport systems because they enable cells of living systems to move molecules in
The overall purpose of the experiments in this lab was to introduce the function and structure of the plasma membrane, describe the workings of diffusion and osmosis, and to demonstrate how different factors such as particle size, temperature, and space of diffusion area affect the rate of diffusion. With the results from the experiments, it can be concluded that all of the factors listed do affect diffusion, and there may be many more than are unaccounted for.