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March 07, 2021, 01:22:50 pm

Author Topic: VCE Biology Question Thread  (Read 2038309 times)  Share 

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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13305 on: January 21, 2021, 09:18:26 pm »
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In red blood cells when oxygen binds to one subunit of haemoglobin, it increases the affinity of neighbouring haemoglobin subunits for oxygen. This is an example of
A cooperativity
B phosphorylation
C covalent modulation
D allosteric modulation

Would this be a can someone explain

Sine

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Re: VCE Biology Question Thread
« Reply #13306 on: January 21, 2021, 10:18:27 pm »
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In red blood cells when oxygen binds to one subunit of haemoglobin, it increases the affinity of neighbouring haemoglobin subunits for oxygen. This is an example of
A cooperativity
B phosphorylation
C covalent modulation
D allosteric modulation

Would this be a can someone explain
Its not really something you can totally explain since it is basically a recall question.

The answer is cooperativity. Phosphorylation is basically adding a phosphate group onto something e.g. an enzyme and both modulations can be relevant to receptors/enzymes.

Oynx

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Re: VCE Biology Question Thread
« Reply #13307 on: January 21, 2021, 11:11:35 pm »
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Its not really something you can totally explain since it is basically a recall question.

The answer is cooperativity. Phosphorylation is basically adding a phosphate group onto something e.g. an enzyme and both modulations can be relevant to receptors/enzymes.

Will or can this be assessed on the end of year exam? Is it apart of the study design?
2021 - Biology | Further mathematics

darkz

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Re: VCE Biology Question Thread
« Reply #13308 on: January 21, 2021, 11:40:39 pm »
+3
Will or can this be assessed on the end of year exam? Is it apart of the study design?

Definitely not relevant to VCE Biology.
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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13309 on: January 24, 2021, 03:55:01 pm »
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For this question
Luke’s arrived at the hospital dehydrated from having spent the past few days with diarrhoea and vomiting. Is a hypertonic solution suitable for him? Explain

Dehydrated therefore there is a low concentration of solutes outside the cell.
- need a solution that will increase the concentration of solutes outside the cell
- A hypertonic solution would not be suitable
- A hypotonic solution would be suitable - solutes would move from inside the cell to outside

This is what I was thinking would this be right

Bluebird

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Re: VCE Biology Question Thread
« Reply #13310 on: January 26, 2021, 07:23:16 pm »
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Hi ATARNotes!

My question is why do chloride ions use facilitated diffusion through a channel protein to cross the plasma membrane? I thought they would use active transport since they are ions.
What molecules do use active transport then?

dedformed

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Re: VCE Biology Question Thread
« Reply #13311 on: January 26, 2021, 08:03:17 pm »
+10
Hi ATARNotes!

My question is why do chloride ions use facilitated diffusion through a channel protein to cross the plasma membrane? I thought they would use active transport since they are ions.
What molecules do use active transport then?

Active transport is required when you're pushing against the concentration gradient, i.e, moving from an area of low concentration to an area of high concentration. If the chloride ions are going down the concentration gradient (from high conc to low conc) this doesn't require energy so it's not active transport even if it's facilitated by protein channels. If the ions are going against the concentration gradient only then is active transport required.

Chlorine ions are charged so they can't permeate the plasma membrane directly.


« Last Edit: January 26, 2021, 08:05:52 pm by dedformed »
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Bluebird

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Re: VCE Biology Question Thread
« Reply #13312 on: January 26, 2021, 10:52:05 pm »
+1
Active transport is required when you're pushing against the concentration gradient, i.e, moving from an area of low concentration to an area of high concentration. If the chloride ions are going down the concentration gradient (from high conc to low conc) this doesn't require energy so it's not active transport even if it's facilitated by protein channels. If the ions are going against the concentration gradient only then is active transport required.

Chlorine ions are charged so they can't permeate the plasma membrane directly.

That helps a lot, thank you!

Erutepa

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Re: VCE Biology Question Thread
« Reply #13313 on: January 27, 2021, 11:49:14 am »
+11
For this question
Luke’s arrived at the hospital dehydrated from having spent the past few days with diarrhoea and vomiting. Is a hypertonic solution suitable for him? Explain

Dehydrated therefore there is a low concentration of solutes outside the cell.
- need a solution that will increase the concentration of solutes outside the cell
- A hypertonic solution would not be suitable
- A hypotonic solution would be suitable - solutes would move from inside the cell to outside

This is what I was thinking would this be right
I don't particularly like this question for the main reason that - from a quick bit of reading on google - it appears dehydration can be hypernatremic/hypertonic (net water loss with a higher sodium concentration than normal), hyponatremic/hypertonic (net water loss with lower sodium concentration than normal, or isonatremic/isotonic (net water loss with a normal sodium concentration. As you would imagine, the treatment for these different types of dehydration would be different.
Assuming of course that the type of dehydration in the question is hypernatremic/hypotonic meaning there is a higher conentration of sodium than normal, then you would want to treat it with a hypotonic solution such to increase the concentration of water in the body without increasing the concentration of sodium (as much). Once again, i am not well versed in how dehydration works, but I imagine that both the extracellular sodium concentration and the extracellular sodium concentration would be increased when dehydrated and so I think that stating that you need to increase the solute concentration outside the cell is not particularly correct. Instead I think we are trying to decrease the concentration of solute (and increase the concentration of water) inside and outside the cell. Administering this hypotonic solution intravenously for example, would increase the water concentration and decrease the solute concentration in the extracellular environment (outside the cell) relative to the extracellular environment. As a result a net diffusion of water into the cells down this concentration gradient would occur, increasing the concentration of water in the cell and decreasing the concentration of sodium (since there is now more water content).
Sorry for how long-winded this reply is - but hopefully this has helped clarify some points. Please let me know if I haven't explained something well or if I have made a mistake somewhere  :)

Please note though that you don't need any knowledge about how dehydration works for VCE bio, hence why I think the question is a little silly - unless ofcourse a question stem is provided explaining the specifics of the situation.
« Last Edit: January 27, 2021, 11:52:54 am by Erutepa »
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Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13314 on: January 31, 2021, 02:10:23 pm »
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Thanks

I'm not sure about my answer for this question if someone could give feedback

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Re: VCE Biology Question Thread
« Reply #13315 on: January 31, 2021, 06:52:43 pm »
+5
Thanks

I'm not sure about my answer for this question if someone could give feedback


i) the conc in the cell increased but the rate it which it moved into the cell (the gradient) was initially constant, then decreased. Therefore, I would not say the rate of uptake increased overtime
ii) I think your answer here is pretty good, make sure you're emphasising what the question wants to hear about, which is how from the graph you can conclude it was diffusion.
iii) Hard to know without having a mark allocation, but for this question it's a good idea to include why you have that net movement of water. 

Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13316 on: February 01, 2021, 12:58:01 pm »
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Ok thanks . So should I say the concentration of molecule w increased inside the cell until around 8 minutes where equilibrium was reached and the net flux is zero.
The uptake of molecule w rapidly increased and then decreased.

Chocolatepistachio

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Re: VCE Biology Question Thread
« Reply #13317 on: February 04, 2021, 07:46:13 pm »
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does anyone know for this question wouldn't all the options be wrong

Owlbird83

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Re: VCE Biology Question Thread
« Reply #13318 on: February 07, 2021, 08:48:32 am »
+4
does anyone know for this question wouldn't all the options be wrong

I think A would be correct.


If you think about the formula, increasing beginning pressure would mean ΔP would increase, and increasing the numerator on the fraction would mean the value would increase so F would be larger.
You can think about it by trying to picture the fluid flowing too, higher pressure would mean more particles in a smaller area in the beginning therefore faster flow.

Let me know if you need more clarification!

(also, this isn't VCE bio, is this from a different course?)
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mishyprzed1

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Re: VCE Biology Question Thread
« Reply #13319 on: February 07, 2021, 12:58:38 pm »
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Hi Guys,

I'm in Bio 3/4 and I have this question.

When mountain climbers reach high altitudes the concentration of gas particles decreases.  What affect would this have on the diffusion of carbon dioxide? Explain.

Thank you to the people who reply :)