Semi-permeable diffusion questions

[indigogirl]

Hi,

I'm having some trouble understanding semipermeable diffusion questions. Does anyone know of a good book or web source with examples?

Also, if anyone could help me out on these...

What is the equilibrium situation?

Left side has90 mM KCL and right side has 20 mM KCl. Membrane in between is permeable to both, with a greater permeability to Cl. Impermeable to water.

Left side is 50 mM glucose, 10mM mannitol. Right side is 20 mM glocose, 20 mM mannitol. Membrane permeable to glucose and water; impermeable to mannitol.

Left side is 5 mM LiCl and 90 mM sucrose. Right side is 50 mM LiCl. Membrane is permeable to Li and water; impermeable to sucrose and Cl.

Thanks.

 

[Aaron Barnard]

The equilibrium situation in all three cases is that the concentrations of the substances on the left and right sides of the membrane are equal. This is because the membrane is semipermeable, so the molecules move from one side to the other until an equilibrium is achieved. The rate at which the molecules move across the membrane is determined by the permeability of the membrane, as well as the concentrations of the two sides.

 

[ravenprp]

Hi there,

There are a few resources that could be helpful in understanding semipermeable diffusion questions. One book that is commonly used in biology courses is "Campbell Biology" by Neil A. Campbell and Jane B. Reece. This book has a section specifically on diffusion and osmosis, which could provide some examples and explanations for you.

In terms of online resources, Khan Academy has a series of videos and practice questions on diffusion and osmosis that may be helpful. Another useful website is Biology Online, which also has explanations and practice questions on these topics.

Now, let's take a look at the three scenarios you mentioned and try to understand the equilibrium situation in each one:

1. In the first scenario, the left side has a higher concentration (90 mM) of KCl compared to the right side (20 mM). Since the membrane is permeable to both K and Cl, but has a greater permeability to Cl, we can expect Cl to diffuse more rapidly than K. This will lead to an equalization of Cl on both sides, resulting in a lower concentration of KCl on the left side. Therefore, the equilibrium situation would be a lower concentration of KCl on the left side, and a higher concentration of KCl on the right side.

2. In the second scenario, the left side has a higher concentration of glucose (50 mM) and a lower concentration of mannitol (10 mM) compared to the right side (20 mM glucose and 20 mM mannitol). Since the membrane is permeable to glucose and water, but impermeable to mannitol, we can expect glucose to diffuse from the left side to the right side, while water will diffuse in the opposite direction. This will lead to an equalization of glucose and water on both sides, resulting in a lower concentration of glucose on the left side and a higher concentration of glucose on the right side. Since mannitol cannot diffuse, its concentration will remain the same on both sides. Therefore, the equilibrium situation would be a lower concentration of glucose and water on the left side, and a higher concentration of glucose and water on the right side.

3. In the third scenario, the left side has a higher concentration of sucrose (90 mM) compared to the right side (50 mM). Since the membrane is permeable to Li and water, but impermeable to sucrose and Cl, we can expect Li to diffuse from the left side to the right side,