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March 29, 2024, 08:07:20 am

Author Topic: VCE Biology Question Thread  (Read 3570954 times)  Share 

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nhuwyn

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Re: VCE Biology Question Thread
« Reply #4590 on: February 08, 2015, 10:11:18 pm »
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Essentially, it increases the efficiency of the cell. A larger surface area provides a larger area for substances to move in/out of the cell or organelle, or it increases the rate of specific reactions (e.g. Oxidative Phosphorylation in aerobic cellular respiration) that occur in membranes.

Thank you so much grannysmith! The answer you gave was really helpful! I really appreciate your help! :)

vox nihili

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Re: VCE Biology Question Thread
« Reply #4591 on: February 09, 2015, 04:29:12 pm »
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Hi!!
Can someone please help me with the explaining the crucial role of membrane systems and organelles for increasing the total membrane surface area within the cell? I'm not too sure on this one :(

To add to what grannysmith said, it follows that things that are super super super folded, are doing a lot of reacting or a lot of transporting—or at the very least have the capacity to do so. So, for example, you know that mitochondria are really trying to get a lot of bang for their buck because the membrane is folded so much.

In the picture in this link: http://highered.mheducation.com/sites/dl/free/0072507470/234439/mc_ch25_fig10.jpg
Why are there 14 H atoms when all H atoms in NADH and FADH2 are combined, when there are only 12 H atoms in Glucose?

Definitely don't need to know, but I think it's because one of the reactions in glyolcysis pinches some hydrogen atoms that naturally occur in the environment, which explains where your two come from. Relatively unremarkable reason to be honest!
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paper-back

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Re: VCE Biology Question Thread
« Reply #4592 on: February 09, 2015, 08:22:27 pm »
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Can the Krebs cycle also be referred to as the Citric acid cycle? Or is it that the Citric acid cycle is a part of the Krebs cycle?

grannysmith

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Re: VCE Biology Question Thread
« Reply #4593 on: February 09, 2015, 08:34:26 pm »
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Can the Krebs cycle also be referred to as the Citric acid cycle? Or is it that the Citric acid cycle is a part of the Krebs cycle?
The first one, pretty much.

cosine

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Re: VCE Biology Question Thread
« Reply #4594 on: February 09, 2015, 08:56:30 pm »
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Why is it that on the Plasma Membrane, the fatty acid chains are said to have a kink in them, which is the reason that the membrane is fluidy, as the unsaturated fatty acids won't become a solid. But why is it that when I see diagrams of the bilayer, the fatty acid chains dont have kinks?

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grannysmith

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Re: VCE Biology Question Thread
« Reply #4595 on: February 09, 2015, 09:01:33 pm »
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Why is it that on the Plasma Membrane, the fatty acid chains are said to have a kink in them, which is the reason that the membrane is fluidy, as the unsaturated fatty acids won't become a solid. But why is it that when I see diagrams of the bilayer, the fatty acid chains dont have kinks?
Not all fatty acid chains in a phospholipid have a kink in them (another way of saying that they are unsaturated). In actual fact, there is a balance between kinked and non-kinked tails. This is to ensure that the plasma membrane is not too fluid that  the cell contents spill out and not too rigid so as to prevent the entry/exit of substances.

With regards to the diagrams, I think that's just for simplicity's sake. :)

cosine

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Re: VCE Biology Question Thread
« Reply #4596 on: February 09, 2015, 09:05:23 pm »
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Not all fatty acid chains in a phospholipid have a kink in them (another way of saying that they are unsaturated). In actual fact, there is a balance between kinked and non-kinked tails. This is to ensure that the plasma membrane is not too fluid that  the cell contents spill out and not too rigid so as to prevent the entry/exit of substances.

With regards to the diagrams, I think that's just for simplicity's sake. :)

Right, thank you grannysmith.

Also, how do water molecules freely diffuse through the membrane if the region between the membrane is non-polar (lipophillic) ?
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grannysmith

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Re: VCE Biology Question Thread
« Reply #4597 on: February 09, 2015, 09:28:35 pm »
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Right, thank you grannysmith.

Also, how do water molecules freely diffuse through the membrane if the region between the membrane is non-polar (lipophillic) ?
Water molecules are so small that they can easily move through the (transient) pores in the plasma membrane.

cosine

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Re: VCE Biology Question Thread
« Reply #4598 on: February 09, 2015, 09:29:47 pm »
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Water molecules are so small that they can easily move through the (transient) pores in the plasma membrane.
Oh, alright so they don't actually go 'through' the phospholipid bilayer, right?
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grannysmith

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Re: VCE Biology Question Thread
« Reply #4599 on: February 09, 2015, 09:35:01 pm »
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Oh, alright so they don't actually go 'through' the phospholipid bilayer, right?
They do, but I get where you're coming from :p

Remember that the plasma membrane is a fluid, as the phospholipids are constantly moving around. This allows temporary 'holes' to appear in the membrane; albeit small, they're large enough for water molecules to go through.

cosine

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Re: VCE Biology Question Thread
« Reply #4600 on: February 09, 2015, 09:44:06 pm »
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They do, but I get where you're coming from :p

Remember that the plasma membrane is a fluid, as the phospholipids are constantly moving around. This allows temporary 'holes' to appear in the membrane; albeit small, they're large enough for water molecules to go through.

Oh alright, I get ya now. Thanks ;)
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Jay.C

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Re: VCE Biology Question Thread
« Reply #4601 on: February 14, 2015, 10:41:18 am »
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We just had our first sac on osmosis yesterday where dialysis tubing was filled with a chelate complex and this was placed into water containing NaOH. It was observed that water moved into the dialysis tubing and this caused the chelate complex to go a light pink colour. I was just wondering why the solution turned pink? Also it was said that if the solution turned pink this means shorter polypeptide chains, why is this? Also if you have any answers to questions I may be asked in the theory component of this sac, they would be much appreciated.

Thanks!  :)
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vox nihili

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Re: VCE Biology Question Thread
« Reply #4602 on: February 14, 2015, 05:07:01 pm »
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We just had our first sac on osmosis yesterday where dialysis tubing was filled with a chelate complex and this was placed into water containing NaOH. It was observed that water moved into the dialysis tubing and this caused the chelate complex to go a light pink colour. I was just wondering why the solution turned pink? Also it was said that if the solution turned pink this means shorter polypeptide chains, why is this? Also if you have any answers to questions I may be asked in the theory component of this sac, they would be much appreciated.

Thanks!  :)

You don't need to be able to answer those questions. They're well beyond year 12 biology :)

Basically though, it's because the sodium ions form a complex (that is, they chelate) with the polypeptides. The shorter the polypeptides, the more places they can bind to, hence brighter pink because the complex causes a pink colour. You really shouldn't be able to understand that though :)
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cosine

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Re: VCE Biology Question Thread
« Reply #4603 on: February 14, 2015, 09:29:57 pm »
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A few questions to wrap up this topic:

- When a red blood cell is placed in a hypertonic solution, I can understand why the water molecules from the cell diffuse out to the solution to reach equilibrium, but why doesn't the solute molecules in the hypertonic solution go to the cell? I know some solutes cannot diffuse through the membrane easily, but they can go through the protein channels etc.. Or do these two processes happen simultaneously, but because diffusion of water is obviously faster, the net movement occurs faster?

- I know now how water molecules or oxygen can readily diffuse through the membrane, through Aquaporins. But, my school textbook says protein channels/carriers have a hypdrophillic lining in them, so that the polar substances can readily diffuse through them in the process of facilitated diffusion. BUT, the Nature of Bio says that both non polar and polar substances can go through these protein molecules. Can anyone please clarify? Thanks :P

Am I going into toooooo much detail? Haha, someone needs to keep this thread alive!
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stewartmahi

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Re: VCE Biology Question Thread
« Reply #4604 on: February 14, 2015, 09:38:35 pm »
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A few questions to wrap up this topic:

- When a red blood cell is placed in a hypertonic solution, I can understand why the water molecules from the cell diffuse out to the solution to reach equilibrium, but why doesn't the solute molecules in the hypertonic solution go to the cell? I know some solutes cannot diffuse through the membrane easily, but they can go through the protein channels etc.. Or do these two processes happen simultaneously, but because diffusion of water is obviously faster, the net movement occurs faster?

- I know now how water molecules or oxygen can readily diffuse through the membrane, through Aquaporins. But, my school textbook says protein channels/carriers have a hypdrophillic lining in them, so that the polar substances can readily diffuse through them in the process of facilitated diffusion. BUT, the Nature of Bio says that both non polar and polar substances can go through these protein molecules. Can anyone please clarify? Thanks :P

Am I going into toooooo much detail? Haha, someone needs to keep this thread alive!
When placed in a hypotonic solution, to balance out the number of solutes both inside and outside water needs to rush into the cell. And to the second statement, water is a polar molecule, meaning it gets attracted to the linings of the aquaporin molecule, therefore allowing it to enter the cell, hope this is helpful