Simple Diffusion

7. Draw a diagram of this set up. Use arrows to depict the movement of each substance in the

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

Watch the solute concentration windows at the side of each beaker for any changes in Na+ and K- concentrations. The Na+ transport rate stops before transport has completed. Why do you think that this happens?

c) Record the amount of substance that dissolved – all, some, a little, or none.

In this lab experiment, half our group observed and measured osmosis using dialysis tubes that were represented as the semipermeable membrane. It is permeable to water and other small molecules but is impermeable to larger molecules such as the sucrose solution used in each of the four beakers and tubing. The other half of our group observed the tonicity of sheep blood to determine whether the blood was isotonic, hypotonic, or hypertonic. The 85 g/dL of NaCl solution was the ideal isotonic number in relation to the sheep blood cells as well as a reference to the other observations of the solutions.

What two parameters are responsible for creating the movement (filtration and reabsorption) of fluid across the capillary wall?

2) When the concentration was at 0.3M, the potato’s cytoplasm and the sucrose solution was isotonic. The concentration of the potato’s cytoplasm was having the same solute concentration as the surroundings. Therefore, there would be no net movement of materials happening.

3. Explain your prediction for the effect Na+ Cl- might have on glucose transport. In other words, explain why you picked the choice that you did. How well did the results compare with your prediction?

13. Understand the transportation of potassium and sodium across plasma membranes. (p. 10 bottom right, p. 20 bottom right, p. 21 diagram)

Consequently, the efferent arteriole, which filters blood away from the glomerulus, is tinier in diameter than the afferent arteriole, which carries blood into each glomerulus. This puts blood under high pressure in the glomerulus; thus it forces tiny molecules and liquid out of the capillary and into the Bowman’s capsule. Soon afterwards, the tiny and liquid molecules cross the epithelium of the Bowman’s capsule, the basement membrane and capillary wall in order to get into the Bowman’s capsule and to arrive in the nephron tubules. The consequence of this is that the filtrate (the tiny and liquid molecules) pass along the remainder of the nephron and helpful substances are reabsorbed along the route. Last of all, “the filtrate flows through the collecting duct and passes out of the kidney along the ureter” as mentioned by (Parson’s, R: p128).

1. What two parameters are responsible for creating the movement (filtration and reabsorption) of fluid across the capillary wall?

1. In passive transport, what determines the direction of movement of small particles? The direction of movement of particles in passive transport is determined by the concentration gradient (diffusion) between the cytoplasm and the extracellular fluid. 2. Why do the molecules in facilitated diffusion need help moving across the plasma membrane? Likely, the molecules are too large to pass unaided through the plasma membrane with the concentration gradient; they need to pass through special transport proteins.

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.

Review Sheet Results 1. Explain the effect that increasing the Na+ Cl- concentration had on osmotic pressure and why it has this effect. How well did the results compare with your prediction? Your answer: The increase of the Na+Cl- concentration increased osmotic pressure the Na+ Cl- molecules diffused through the 50 mwco membranes and didn't go through the 20 mwco membranes. the more Na+Cl- we added to the 20 mwco membrane, the more the osmotic pressure went up. When I looked at my results I noticed when Na+Cl- was added to the 50 mwco membrane, there was no increase in osmotic pressure. This is becasue the Sodium chloride couldn't diffuse through the 50 mwco membranes. The higher concentration of molecues on one side of the mwco membrane forces the water movement to move to the side of greater solute concentration. 2. Describe one way in which osmosis is similar to simple diffusion and one way in which it is different. Your answer: Osmosis is similar to simple diffusion because both of these precesses have the passive transport characteristic. This is where particles in a solution move from an area of high solute concentration to an are of low solute concentration. Also neither of these processes need energy from an outside source to function. Osmosis is different than simple diffusion because in osmosis, if we have a selectively permeable membrane, this membrane is

3. a. The first error will be when transferring the benzoic acid from the weigh paper to the vial. The benzoic acid is spilled. Then, the second one will be when pipetting and transferring the methylene chloride because I might spill some of the methylene chloride. The third one will be when pipetting the two layers, either I could not pipet all of the bottom layer or I accidentally pipet the top layer.