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Author Topic: VCE Biology Question Thread  (Read 3570600 times)  Share 

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Kalopsic

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Re: VCE Biology Question Thread
« Reply #4680 on: February 17, 2015, 09:52:36 pm »
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random question: why is nitrogen considered to be an essential element for all living things?

Nitrogen is found in amino acids. Amino acids make up protein and protein is used everywhere. Without protein, we wouldn't have enzymes or even RNA polymerase which is essential in protein production. Proteins are very very important.
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vox nihili

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Re: VCE Biology Question Thread
« Reply #4681 on: February 17, 2015, 10:20:37 pm »
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random question: why is nitrogen considered to be an essential element for all living things?
Nitrogen is found in amino acids. Amino acids make up protein and protein is used everywhere. Without protein, we wouldn't have enzymes or even RNA polymerase which is essential in protein production. Proteins are very very important.

Also found in nitrogenous bases and some carbohydrates
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Bestie

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Re: VCE Biology Question Thread
« Reply #4682 on: February 17, 2015, 10:36:41 pm »
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α-Keratin is a fibrous protein that can be
stretched to about twice its length and is elastic.
Silk fibroin is also a fibrous protein but is not
elastic. Silk has great tensile strength and is much
stronger than hair. Explain these observations in
terms of the structure of their protein molecules.


is the answer related ti teriary structure and how silk may have stronger bonds there?

bts

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Re: VCE Biology Question Thread
« Reply #4683 on: February 17, 2015, 10:39:14 pm »
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Also found in nitrogenous bases and some carbohydrates
Nitrogen is found in amino acids. Amino acids make up protein and protein is used everywhere. Without protein, we wouldn't have enzymes or even RNA polymerase which is essential in protein production. Proteins are very very important.
thank you guys ! ~

also just wondering why cellulose and glycogen have different physical properties/biological functions but both are polysaccarides made up of glucose monomers?

Yacoubb

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Re: VCE Biology Question Thread
« Reply #4684 on: February 17, 2015, 10:55:18 pm »
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thank you guys ! ~

also just wondering why cellulose and glycogen have different physical properties/biological functions but both are polysaccarides made up of glucose monomers?

Because glycogen is actually made of alpha glucose sub-units, while cellulose is made of beta glucose sub-units. :)
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cosine

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Re: VCE Biology Question Thread
« Reply #4685 on: February 18, 2015, 03:35:25 pm »
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A student has a beaker which has a semi permeable membrane running through the middle. If on the left side of the membrane, there is a sucrose solution, and on the right side of the membrane there is distilled water. What would happen after 5 hours?


This question sort of got me... Look, distilled water means there are absolutely no solutes in it. So, obviously in the left side of the membrane (the sucrose solution) there is more solutes as compared to the distilled water. So, after 5 hours, would the distilled water completely diffuse through the membrane and into the sucrose solution? I would say all of the water will, because it will naturally try to reach equilibrium, but because it has no solutes at all, the left side will keep absorbing the water untill there is none left in the right side.


Is what I said true? Because this question deffs questioned my performance in bio, completely destroyed my confidence :/
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cosine

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Re: VCE Biology Question Thread
« Reply #4686 on: February 18, 2015, 03:49:48 pm »
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Name two processes that cannot occur if protein channels were not present in the cell membrane.

I honestly don't know, facilitated diffusion can still occur right, because the large polar molecules or ions can still diffuse through the carrier proteins? Anyone?
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cosine

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Re: VCE Biology Question Thread
« Reply #4687 on: February 18, 2015, 04:29:06 pm »
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Sorry about the influx of questions :3


In an experiment to investigate the use of salt and surcrose solutions as a potential method of dehydrating apricots, researchers found that although salt had some advantages, one disadvantage was that the fruit gained a salty taste due to the movement of salt ions. The sucrose molecules did not enter the apricots however. How do salt ions normally cross the cell membrane? Explain why the salt ions moved across the membranes of the cells in the apricots and the sucrose molecules did not.


Salt movement can be a form of both facilitated diffusion and active transport. So would a reasonable answer be that salt ions typically pass through the cell membrane via protein channels?

For the second part, would it be correct to say that the salt ions moved into the cells of the apricot because as we know there is a lower salt concentration in apricots, so the salt ions went down their concentration gradient and diffused via proteins into the cells of the apricot, hence the salty taste? And the sucrose didn't go into the cells because we assume that the apricot cells have a much greater concentration of sucrose.

Thanks guys :)
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Yacoubb

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Re: VCE Biology Question Thread
« Reply #4688 on: February 18, 2015, 06:06:43 pm »
+1
Sorry about the influx of questions :3


In an experiment to investigate the use of salt and surcrose solutions as a potential method of dehydrating apricots, researchers found that although salt had some advantages, one disadvantage was that the fruit gained a salty taste due to the movement of salt ions. The sucrose molecules did not enter the apricots however. How do salt ions normally cross the cell membrane? Explain why the salt ions moved across the membranes of the cells in the apricots and the sucrose molecules did not.


Salt movement can be a form of both facilitated diffusion and active transport. So would a reasonable answer be that salt ions typically pass through the cell membrane via protein channels?

For the second part, would it be correct to say that the salt ions moved into the cells of the apricot because as we know there is a lower salt concentration in apricots, so the salt ions went down their concentration gradient and diffused via proteins into the cells of the apricot, hence the salty taste? And the sucrose didn't go into the cells because we assume that the apricot cells have a much greater concentration of sucrose.

Thanks guys :)

Well generally salt is NaCl. You have your Na+ (sodium) and Cl-(chloride) ions. They are capable of moving through specific protein channels. Remember that the membrane is selectively permeable, allowing the movement of specific molecules into and out of the cell via the membrane. Evidently, sucrose does not fall into this category of specific molecules.

Typically, yes. As aforementioned, the typical route of ions is protein channels.

If we're inferring the movement of ions by facilitated diffusion, then we know it is the movement of these ions from an area of high solute concentration (i.e. the solution) to an area of low solute concentration (i.e. the inside of the apricot).

Hope this helped :)
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cosine

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Re: VCE Biology Question Thread
« Reply #4689 on: February 18, 2015, 06:25:54 pm »
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Well generally salt is NaCl. You have your Na+ (sodium) and Cl-(chloride) ions. They are capable of moving through specific protein channels. Remember that the membrane is selectively permeable, allowing the movement of specific molecules into and out of the cell via the membrane. Evidently, sucrose does not fall into this category of specific molecules.


So the NaCl ions diffused into the apricot, causing the salty taste. But also because the solute concentration is higher in the solution than the apricot, osmosis also occurred and the water diffused from the apricot to the solution of NaCl. And in this case, the experiment is supported as we are dehydrating the apricot, right?

Thanks Yacoubb, very helpful!!
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Jay.C

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Re: VCE Biology Question Thread
« Reply #4690 on: February 18, 2015, 07:52:21 pm »
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Now I understand that substances that do not dissolve in water are hydrophobic but I just realised I've never really asked why they don't!

Is it because they are not charged and thus water cannot pull there bonds apart?? Cant believe I've never questioned this.  :-\
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vox nihili

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Re: VCE Biology Question Thread
« Reply #4691 on: February 18, 2015, 08:22:38 pm »
+1
Now I understand that substances that do not dissolve in water are hydrophobic but I just realised I've never really asked why they don't!

Is it because they are not charged and thus water cannot pull there bonds apart?? Cant believe I've never questioned this.  :-\

It's because there's really no attraction between water and the hydrophobic substances. Water is really polar, which means it has partial charges. Hydrophobic substances are uncharged, and thus, don't form particularly strong bonds with polar water. Water much prefers to bond with itself (because of the partial charges) and the hydrophobic substances, as a consequence, tend to stick together too.

The basic idea is that like bonds with like; things that have the same kind of charge status (no charge, partial, full) will tend to bond :)
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Jay.C

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Re: VCE Biology Question Thread
« Reply #4692 on: February 18, 2015, 09:44:45 pm »
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It's because there's really no attraction between water and the hydrophobic substances. Water is really polar, which means it has partial charges. Hydrophobic substances are uncharged, and thus, don't form particularly strong bonds with polar water. Water much prefers to bond with itself (because of the partial charges) and the hydrophobic substances, as a consequence, tend to stick together too.

The basic idea is that like bonds with like; things that have the same kind of charge status (no charge, partial, full) will tend to bond :)

Thanks! I also have another question what does the study design mean when it says 'the nature of the proteome'??
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vox nihili

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Re: VCE Biology Question Thread
« Reply #4693 on: February 18, 2015, 11:19:23 pm »
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Thanks! I also have another question what does the study design mean when it says 'the nature of the proteome'??

The proteome is all the proteins produced by an organism

That^
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Yacoubb

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Re: VCE Biology Question Thread
« Reply #4694 on: February 19, 2015, 12:48:22 am »
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Thanks! I also have another question what does the study design mean when it says 'the nature of the proteome'??

Adding to what Mr. T-Rav has mentioned, you essentially need to know what the proteome is, and also dabble a bit into proteomics, looking at why scientists do not focus on singular proteins in research, and instead look at groups of proteins at a given time, etc.
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