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March 29, 2024, 06:07:23 am

Author Topic: VCE Biology Question Thread  (Read 3570853 times)  Share 

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RazzMeTazz

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Re: VCE Biology Question Thread
« Reply #735 on: February 21, 2014, 10:09:00 pm »
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Is it generally easier for small non-polar substances to pass through the cell membrane by simple diffusion or is it easier for small polar substances to?

I always thought polar substances had a bit more trouble, as the interior of the phospholipid bilayer is non-polar?

grannysmith

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Re: VCE Biology Question Thread
« Reply #736 on: February 21, 2014, 10:14:23 pm »
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What is the definition of osmosis? Do I need to include info about the semi permeable membrane?
Thanks in advance :D

Yes, you should.
Osmosis is the passive, net movement of water molecules across a semi permeable membrane, from a region of high water concentration (low solute concentration) to a region of low water concentration (high solute concentration).

nerdmmb

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Re: VCE Biology Question Thread
« Reply #737 on: February 21, 2014, 10:15:17 pm »
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What is the definition of osmosis? Do I need to include info about the semi permeable membrane?
Thanks in advance :D

Osmosis the net movement of water molecules from a region of high water potential to a region of low water potential along the osmotic gradient.

You don't have to mention the semi-permeable membrane but you can :)

Rishi97

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Re: VCE Biology Question Thread
« Reply #738 on: February 21, 2014, 10:16:27 pm »
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Yes, you should.
Osmosis is the passive, net movement of water molecules across a semi permeable membrane, from a region of high water concentration (low solute concentration) to a region of low water concentration (high solute concentration).


Thanks heaps...  :)
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grannysmith

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Re: VCE Biology Question Thread
« Reply #739 on: February 21, 2014, 10:16:51 pm »
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Is it generally easier for small non-polar substances to pass through the cell membrane by simple diffusion or is it easier for small polar substances to?

I always thought polar substances had a bit more trouble, as the interior of the phospholipid bilayer is non-polar?

Well, small non polar substances would diffuser across easier, although some small polar substances are tiny enough to slip through the tiny pores of the plasma membrane (e.g. water).

nerdmmb

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Re: VCE Biology Question Thread
« Reply #740 on: February 21, 2014, 10:18:14 pm »
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Is it generally easier for small non-polar substances to pass through the cell membrane by simple diffusion or is it easier for small polar substances to?

I always thought polar substances had a bit more trouble, as the interior of the phospholipid bilayer is non-polar?

Non-polar substances can easily diffuse through the membrane and small polar molecules can as well but larger polar (hydrophilic) and charged molecules require protein channels.

The interior of the phospholipid is non-polar however the phosphate heads are not but since the membrane is porous, water molecules and certain other substances can diffuse through.

Note that the factors which affect diffusion are size, charge and polarity.

Rishi97

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Re: VCE Biology Question Thread
« Reply #741 on: February 21, 2014, 10:18:52 pm »
+1
Osmosis the net movement of water molecules from a region of high water potential to a region of low water potential along the osmotic gradient.

You don't have to mention the semi-permeable membrane but you can :)
Thanks nerdmmb. You have really helped me heaps for this upcoming bio sac :) :) :)
2014: VCE completed
2015-2017: BSc at Melb Uni

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nerdmmb

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Re: VCE Biology Question Thread
« Reply #742 on: February 21, 2014, 10:18:58 pm »
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Well, small non polar substances would diffuser across easier, although some small polar substances are tiny enough to slip through the tiny pores of the plasma membrane (e.g. water).

Sorry oddly,
 I didn't see your posts!

MM1

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Re: VCE Biology Question Thread
« Reply #743 on: February 21, 2014, 10:20:15 pm »
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Is it generally easier for small non-polar substances to pass through the cell membrane by simple diffusion or is it easier for small polar substances to?

I always thought polar substances had a bit more trouble, as the interior of the phospholipid bilayer is non-polar?

Yes, non-polar substances are able to readily diffuse through the cell membrane because it has a greater affinity for the hydrophobic region. Whilst, polar molecules such as water are able to diffuse through small spaces between the phospholipids (because of their small size), it is relatively  harder for them to break that initial barrier/repulsion to enter. But they are able to, nonetheless.

MM1

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Re: VCE Biology Question Thread
« Reply #744 on: February 21, 2014, 10:21:36 pm »
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What is the definition of osmosis? Do I need to include info about the semi permeable membrane?
Thanks in advance :D

Yes, you always need to, whatever the scenario may be.

'Osmosis is the passive net movement of free water molecules across a semi-permeable membrane from a region of low solute concentration (high water potential) to a region of high solute concentration (low water potential), along an osmotic gradient. [To attain equilibrium].


nerdmmb

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Re: VCE Biology Question Thread
« Reply #745 on: February 21, 2014, 10:22:22 pm »
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I was just wondering, do water molecules enter through the pores or do they push against the phosphate heads to do so?

Just a little confused because I was told that they break off a small portion of the phosphate heads to enter which doesn't really make sense.

RazzMeTazz

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Re: VCE Biology Question Thread
« Reply #746 on: February 21, 2014, 10:25:25 pm »
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Sorry oddly,
 I didn't see your posts!

Thanks for the help, guys! :)

alchemy

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Re: VCE Biology Question Thread
« Reply #747 on: February 21, 2014, 10:44:21 pm »
+1
I was just wondering, do water molecules enter through the pores or do they push against the phosphate heads to do so?

Just a little confused because I was told that they break off a small portion of the phosphate heads to enter which doesn't really make sense.

They pass through the gaps (pores).

vox nihili

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Re: VCE Biology Question Thread
« Reply #748 on: February 21, 2014, 10:49:15 pm »
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I was just wondering, do water molecules enter through the pores or do they push against the phosphate heads to do so?

Just a little confused because I was told that they break off a small portion of the phosphate heads to enter which doesn't really make sense.

They pass through gaps in the membrane, but as alondouek has mentioned here before (don't worry that's not being snippy, it's just giving credit where it's due!), most water actually passes through channel proteins called aquaporins.
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Reus

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Re: VCE Biology Question Thread
« Reply #749 on: February 21, 2014, 10:53:23 pm »
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Got the enzyme prac sac, in about 2 weeks time! Anything I should know prior to it, or will it be straight forward?
Thanks!
2015: Bachelor of Science & Bachelor of Global Studies @ Monash University