Do Some Particles Move By Diffusion? How Can A Model Be Created?

5. Is the bag hypotonic with regards to the Lugol’s solution, or the beaker? What about the

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

Membranes contain phospholipid bilayer these are two layers of phospholipids which are facing in opposite directions to each other. The non-polar tails are hydrophobic which are water-hating, what makes it difficult for polar molecules/ions to pass through them are the fatty acid tails which also act as a barrier to water-soluble substances. These molecules move in and out of the cell by diffusion, osmosis and active transport. Diffusion is the net movement of particles down a concentration gradient for example when gases move about and will move from where there is a high concentration to where they are in lower concentration. By osmosis, the diffusion of water through the plasma membrane is possible because the lipids bilayers are water-resistant to important molecules and small molecules like oxygen and carbon dioxide, these molecules and ions diffuse freely across the cell membrane. By active transport, ions and molecules are forced using metabolic energy to move against their concentrated gradient.

Gummy Bears, cup, paper towels, triple beam balance, water, wax paper, metric ruler, calculator, and pencil.

The purpose of these experiments is to examine the driving force behind the movement of substances across a selective or semiperpeable plasma membrane. Experiment simulations examine substances that move passively through a semipermeable membrane, and those that require active transport. Those that move passively through the membrane will do so in these simulations by facilitated diffusion and filtration. The plasma membrane’s structure is composed in such a way that it can discriminate as to which substances can pass into the cell. This enables nutrients to enter the cell, while keeping unwanted substances out. Active

C) Again, rinse the saucepan and then add 250 grams of sugar to your 250ml graduated cylinder and then add water up to the 250ml mark. You will place a small piece of plastic wrap over the top of the graduated cylinder (or parafilm if you have that), and mix the sugar with the water. Then pour the contents into a small saucepan over the stove. You will fill the graduated cylinder up to the 250ml mark again and then pour the tap water into the saucepan as well. You will now heat the mixture on the stove and stir until the sugar has dissolved. Once this has happened, you will remove the solution from the saucepan, pour the solution into a container and label that container 50% sugar solution.

Materials move into and out of cells through either passive transport or active transport. Passive transport includes diffusion and osmosis. Molecules tend to move from crowded to less crowded in order to achieve a balance or to reach homeostasis. The cell membrane is selectively permeable which allows the movement of substances, especially oxygen, water, food molecules, carbon dioxide, and waste products, into or out of the cell without the use of energy. Movement occurs when there are unequal concentrations of a substance inside and outside of the cell.

Hydrate the yeast packets in a beaker with 400 mL of distilled water at a 10% concentration. In a 50 mL

lab bench. Place a beaker from the drawer on the stir plate. Drag the bottle of NH3 to the 5 mL graduated cylinder (the smallest one) by the sink and fill the cylinder by dropping the bottle on the cylinder. Now drag the 5 mL graduated cylinder to the beaker on the stir plate and add the 5 mL of

A major determinant of diffusion in a biological system is membrane permeability. Small, uncharged molecules pass through cellular membranes easily, while most and/or charged molecules cannot pass through the membrane. The movement of water across a selectively permeable membrane, like the plasma membrane

The cell membrane is selective due to the double layer of membrane phospholipids. The way the molecules pass through

Cells in all living things have an outer layer known as the cell membrane. The structure of the cell membrane consists of the phospholipid bilayer organized by the arrangement of hydrophilic heads and hydrophobic tails. It is a selectively permeable membrane, where it divides the outer environment from the interior of the cell. It can control substances moving in and out of living cells. Certain molecules like gases, water, and food are permitted to pass the membrane through the method of diffusion. Diffusion refers to the process in which molecules move on the concentration gradient, where they move from an area of high concentration to an area of low concentration. A type of diffusion is known as osmosis. It is the diffusion of water moving across the selectively permeable membrane. In this lab, students will be using eggs to construct an experiment to get a better study on how osmosis works in a cell. The eggs will be soaked in vinegar solution to remove their shells to expose each inner layer that resembles a selectively permeable membrane. The egg shell is composed of calcium carbonate that would dissolves in acidic solution such as vinegar. In the chemical reaction, it releases carbon dioxide gas. After the removal of the egg shell, it will be ready to be able to construct the experiment.

Work in groups of two and wear safety googles. Label the first half of the paper towel with #1, #2, #3, and #4 making sure that there was enough space below each number to place a cup. On the second half of the paper towel, label A, B, C, and D. Also making sure that there was enough space below each letter to place a cup. Next, place a cup below each letter and number. Find the graduated cylinder marked “Enzyme”. Take the graduated cylinder and fill and it with 40 ml of the potato solution. Pour this into cup below number 1. Next, use the same beaker, fill it with 30 ml of the potato solution and pour into the cup below number 2. Find the graduated cylinder marked “Distilled Water”. Use this beaker to fill up 10 ml of distilled water and also pour it into cup below number 2.

3. Use a sterile pipette to transfer 0.1 ml of each dilution on to a MacConkey agar plate.

One of the main structures of a biotic cell is a cell membrane which is produced from a phospholipid (Reece et al., 2011). When a huge number of phospholipids, each comprising a hydrophilic head and a hydrophobic tail, gather, they rearrange into what is known as a Fluid Mosaic plasma membrane (Reece et al., 2011). This membrane is always in motion and the mosaic created is due to the proteins within the membrane (Reece et al., 2011). Additionally, the membrane is also selectively permeable which means that not every substance moves across the membrane (Reece et al., 2011). Factors such as the polarity of a molecule and the relative size of the molecule greatly affect the rate of dispersion through the plasma membrane (Bio. Sciences