Diffusion (1 Viewer)

[tam89]

what factors will affect the speed of diffusion??

Thanks

 

[Dr_Doom]

Temperature is one..

There was an experiment I did, where we studied the diffusion of a cystal dye in cold, warm and hot water. With the hot water, it spread out the fastest..

I'm not sure if there are other factors.. I forget lol, check your hienemann

 

[tam89]

Thanks.

Also.. not sure if these answers are right:

(i) Name 2 molecules that cross the plasma membrane by diffusing through pores.

Oxygen gas and water?

(ii) Name 2 molecules that cross the plasma membrane by dissolving in the lipid component of the plasma membrane.

Carbon dioxide, urea?

 

[Dr_Doom]

Yes but I thought water used osmosis... I'd say your right, not sure about urea though...

I will look em up when I get home..

 

[bluesky100]

what factors will affect the speed of diffusion??

Thanks

Here are a few examples--

*membrane permeability 0- diffusion through a membrane depends on how permeable it is to the particles. Eg potassium ions diffuse more rapidly than sodium ions through the plasma membrane. Nonpolar and lipid soluble substances eg oxygen, nitric oxide, alcohol will diffuse through the phospholipid regions of a plasma membrane.

* Membrane surface area - a smaller SA = molecules will diffuse more rapidly.

* molecular weight - /molecules (eg protein) move more sluggishly than + diffuse more slowly than light particles eg gases

* concentration gradient - the concentration difference between 2 points. Particles will diffuse more rapidly if there is a greater conc. difference between 2 points.



Hope this helps.

 

[Dr_Doom]

What dot point would this be related to in the syllabus...

 

[tam89]

This is a preliminary subject: Patterns of nature.

Thankyou guys for ur help.

 

[Dr_Doom]

How much of preliminary work do we need to know for the HSC.. Is it 30%?

 

[katie_tully]

You will never be tested in the HSC, on what you learnt in Preliminary. Not directly anyway. But it is assumed that you retain your prior knowledge from the Preliminary course when learning the content in the HSC course.
Maintaining a Balance in the HSC course relies heavily on your previous knowledge of osmosis, diffusion and such.
You cannot really put a value on the amount of information you are required to retain from the Prelim course, so it is helpful if you try and remember the fundamentals.

 

[Dr_Doom]

Thanks, I pretty much understand it all so I guess I'll be right not revising peliminary work

 

[Survivor39]

Thanks.

Also.. not sure if these answers are right:

(i) Name 2 molecules that cross the plasma membrane by diffusing through pores.

Oxygen gas and water?

(ii) Name 2 molecules that cross the plasma membrane by dissolving in the lipid component of the plasma membrane.

Carbon dioxide, urea?

hmm.. I think for 1, they are looking for answers such as Na+ and Cl- ions, as they actually diffuse through pores of the membrane.

For 2, I don't know what it is trying to ask but O2 and CO2 seems correct, as they are dissolved in water and can cross the membrane without going through pores.

 

[michaelhazan]

Any one know any good preliminary BIO sites

 

[Dr_Doom]

I know some good preliminary BIO books. I made some really good notes on the preliminary course. They are the best notes you will ever get your hands on. Each syllabus dot point is there with a detailed answer! I will attach it to this message!

http://rapidshare.de/files/17079239/Biology_Topic_Review_by_Dr_Doom.zip.html

Click above to download! Couldn't attach to message sorry.

 

[yoakim]

kenetic energy affects the rate of diffusion also
thanks dr doom for the summary notes...

Edit: the link doesn't work...dead link