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December 14, 2019, 03:53:29 am

Author Topic: VCE Biology Question Thread  (Read 1455208 times)  Share 

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BitcoinEagle

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Re: VCE Biology Question Thread
« Reply #12105 on: October 21, 2019, 07:56:54 am »
+3
this is a reallyy simple question but the answer to this question in a prac exam is tripping me up so i'm wondering if someone can please clarify it for me

i'm pretty sure that channel proteins are involved in facilitated diffusion only, right?

Correct! Channel proteins can be used only in facilitated diffusion as molecules move through it down its concentration gradient without ATP Input.
I believe it would be carrier proteins (which are a little bit different) which can be used for both active and passive transport. Clarification would be great on this point though.
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Re: VCE Biology Question Thread
« Reply #12106 on: October 21, 2019, 10:10:43 am »
+5
this is a reallyy simple question but the answer to this question in a prac exam is tripping me up so i'm wondering if someone can please clarify it for me

i'm pretty sure that channel proteins are involved in facilitated diffusion only, right?
It's more complicated than you're taught in VCE. For the exam, just assume that channel proteins are only for facilitated diffusion, and that carrier proteins can be used for both - but if you get a question about active transport, talk about carriers not channels.
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IThinkIFailed

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Re: VCE Biology Question Thread
« Reply #12107 on: October 21, 2019, 06:21:27 pm »
0
This is a pretty good answer. The reason that second and third responses are successively more extreme, is simply because, in each successive response, more antibodies are created which bind to more mast cells. Hence, when the body is reexposed to the antigen, each successive time, more histamine is released and hence the inflammation symptoms including constriction of airways, reddening and swelling etc increase. This can be dangerous if the levels of histamine are high enough.

To everyone else:
In STAV 2018, Q5:

Transcription in:
a) Eukaryotic cells differ from that in prokaryotic cells as eukaryotic cells do not have promoters like eukaryotic cells.
b)Eukaryotic cells differ from that in prokaryotic cells as eukaryotic cells require transcription factors to bind to a promoter region whereas prokaryote cells do not
C) Both eukaryotic cells and prokaryotic cells occur in the cytosol of the cell.
D) Both eukaryotic and prokaryotic cells involve modification of the transcribed RNA.

How is the correct answer discerned here?
 ;)

Thanks for the help!

Now, I have another question:

Is tertiary structure synonymous with 3D shape of a protein?

Also, does this response make sense when explaining the impact of a very high temperature above optimum on enzyme reaction rate?

With high temperatures above optimum, the enzymes bonds denature, leading to a conformational change in the 3D shape of the enzyme, changing its active site shape and reducing the ability of the substrate to bind to the active site, reducing the rate of reaction.

Iím not sure if I need to specific what type of bonds e.g is it hydrogen bonds, or disulphides bonds, and I also feel it can be more concise but i canít seem to discern which details to remove.
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Re: VCE Biology Question Thread
« Reply #12108 on: October 21, 2019, 07:03:39 pm »
0
It's more complicated than you're taught in VCE. For the exam, just assume that channel proteins are only for facilitated diffusion, and that carrier proteins can be used for both - but if you get a question about active transport, talk about carriers not channels.
Thank you very much!! ;D
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Re: VCE Biology Question Thread
« Reply #12109 on: October 21, 2019, 11:01:19 pm »
+1
Thanks for the help!

Now, I have another question:

Is tertiary structure synonymous with 3D shape of a protein?

Also, does this response make sense when explaining the impact of a very high temperature above optimum on enzyme reaction rate?

With high temperatures above optimum, the enzymes bonds denature, leading to a conformational change in the 3D shape of the enzyme, changing its active site shape and reducing the ability of the substrate to bind to the active site, reducing the rate of reaction.

Iím not sure if I need to specific what type of bonds e.g is it hydrogen bonds, or disulphides bonds, and I also feel it can be more concise but i canít seem to discern which details to remove.

I'd say that the tertiary structure is the overall three dimensional shape of the protein, as technically alpha helices and beta pleated sheets are 3D too; tertiary is the folding of these structures spatially through the bonding between the variable R groups (side chains).

 I think you can get away with not mentioning the specific bonds, although if your worried you can just chuck hydrogen bonds in brackets
This is how i describe high temperature's effect on enzyme activity:
As the temperature exceeds the enzyme's optimal, bonds are broken in it's tertiary/secondary structure, distorting the structure of the active site to the extent where it will no longer be able to bind to the substrate, thereby reducing the rate and ability to catalyse. Basically the same length as yours! ;D

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Re: VCE Biology Question Thread
« Reply #12110 on: October 21, 2019, 11:34:32 pm »
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Quick question,

As I am going through old exams (2012-2002), when it comes to describing/explain transcription, they also want me to add stuff about post transcription modification of the pre- mRNA that was produced.

When I spoke to me teacher she said that this would be incorrect now as it does say post transcription so not being apart of transcription.
So my question is, on the 2019 exam if I have to describe transcription, do I also explain about how pre-mRNA undergoes post transcription modification where the introns are removed and a poly A tail and a methyl cap is added?
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xenx

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Re: VCE Biology Question Thread
« Reply #12111 on: October 21, 2019, 11:43:29 pm »
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Hey,
When talking about structural morphology and types of evolution, do I say they share/don't share a common ancestor or a recent common ancestor?
Also, is using the term unrelated species correct? cus aren't all species related. What would be a better term to use
Thanks 

DBA-144

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Re: VCE Biology Question Thread
« Reply #12112 on: October 22, 2019, 12:09:54 am »
+5
Quick question,

As I am going through old exams (2012-2002), when it comes to describing/explain transcription, they also want me to add stuff about post transcription modification of the pre- mRNA that was produced.

When I spoke to me teacher she said that this would be incorrect now as it does say post transcription so not being apart of transcription.
So my question is, on the 2019 exam if I have to describe transcription, do I also explain about how pre-mRNA undergoes post transcription modification where the introns are removed and a poly A tail and a methyl cap is added?


As a general rule, the question will kind of indicate to you what you need to talk about. Obviously, if they are making a reference to modifications, you need to talk about them. keep in mind those questions are from about 2-3 study designs ago.

Hey,
When talking about structural morphology and types of evolution, do I say they share/don't share a common ancestor or a recent common ancestor?
Also, is using the term unrelated species correct? cus aren't all species related. What would be a better term to use
Thanks 

Either is fine. Some instances require you to talk about a recent common ancestor. You can just say not closely related. This sort of distinction isn't really that important from what I have seen so far however. I am no expert so you'll need others to confirm.

Thanks for the help!

Now, I have another question:

Is tertiary structure synonymous with 3D shape of a protein?

Also, does this response make sense when explaining the impact of a very high temperature above optimum on enzyme reaction rate?

With high temperatures above optimum, the enzymes bonds denature, leading to a conformational change in the 3D shape of the enzyme, changing its active site shape and reducing the ability of the substrate to bind to the active site, reducing the rate of reaction.

Iím not sure if I need to specific what type of bonds e.g is it hydrogen bonds, or disulphides bonds, and I also feel it can be more concise but i canít seem to discern which details to remove.

Given this is not chemistry, I don't believe bonding is that important here. I don't think you need a more concise answer tbh.
Please remember I am not very good at biology so keep this in mind when reading through! :)
« Last Edit: October 22, 2019, 12:11:33 am by DBA-144 »

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12113 on: October 22, 2019, 04:13:25 pm »
+3
Hey,
When talking about structural morphology and types of evolution, do I say they share/don't share a common ancestor or a recent common ancestor?
Also, is using the term unrelated species correct? cus aren't all species related. What would be a better term to use
Thanks
Saying recent common ancestor is more accurate, so I'd use that. It's unlikely that you'd ever have to say unrelated species in a VCAA exam. Try and avoid it because you're right that it's not actually correct. If it comes up it'll be in the context of comparing species so you'll probably just be able to word you answer differently to say that they're not closely related.

Also, does this response make sense when explaining the impact of a very high temperature above optimum on enzyme reaction rate?

With high temperatures above optimum, the enzymes bonds denature, leading to a conformational change in the 3D shape of the enzyme, changing its active site shape and reducing the ability of the substrate to bind to the active site, reducing the rate of reaction.

Iím not sure if I need to specific what type of bonds e.g is it hydrogen bonds, or disulphides bonds, and I also feel it can be more concise but i canít seem to discern which details to remove.
Depending on the question you might need to change your language a bit - eg saying "eliminating the ability of the substrate to bind" or "preventing the enzyme from functioning", but otherwise this answer should be fine.

As the temperature exceeds the enzyme's optimal, bonds are broken in it's tertiary/secondary structure, distorting the structure of the active site to the extent where it will no longer be able to bind to the substrate, thereby reducing the rate and ability to catalyse. Basically the same length as yours! ;D
Wouldn't mention secondary structure. The bonds holding that together are significantly stronger than hydrogen bonds and you'll probably be marked as wrong for saying that a bit of temperature will break them.
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Re: VCE Biology Question Thread
« Reply #12114 on: October 22, 2019, 06:40:53 pm »
0
Thank you ssillysnakes, Rom_Dog, Bri MT and PhoenixxFire for the help. It was hard to understand at first but now I get it!  ;D

I had more questions to ask.

From the 2008 VCAA Exam 2, for question 17, I picked the answer D but the answer is B and I was wondering why and why it wouldn't be D? I knew for sure that the answer was either B or D though.

From the 2011 Exam 2 short answer, question 7 c i, I wrote that DNA has a low mutation rate so differences cannot easily be seen but VCAA's answer said that it's because the DNA has degraded. Would my answer be valid?

From the 2007 Exam 1, question 3 c , I designed an experiment such that the beakers were exposed to temperatures in increasing increments like one beaker is exposed to 10 degrees, the other 20 degrees. Then a graph had to be constructed so you could see the enzyme activity and see if it was lower or higher enzyme activity. Although, I'm not sure if this is a valid experiment as you are not actively testing the 37 optimum temperature and comparing it to another temperature to see the comparison. So, I was wondering if my experimental design would be valid?

From the 2007 Exam 2, question 2g, I'm a bit confused as what do the examiner reports mean when they say use a different gene loci? Does that mean that the DNA in the sample means all the DNA of the suspects? Because, I  wrote the answer of use another sample from the crime scene.

Also, how do T cytotoxic cells destroy cells?
I know that they induce apoptosis but do they do anything else and how do they do that?
« Last Edit: October 22, 2019, 06:56:59 pm by Evolio »
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ErnieTheBirdi

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Re: VCE Biology Question Thread
« Reply #12115 on: October 22, 2019, 08:02:09 pm »
+1
Hey everyone,
I was just wondering whether anyone knew where I could find some resources such as practise exams or practice questions maybe even videos that could help me ace my Unit 2 Biology exam. I know they could be really rare due to it being a year 11 subject but I still want to do well on it. Hopefully, someone could help me out? Thanks, everyone!

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Re: VCE Biology Question Thread
« Reply #12116 on: October 22, 2019, 09:42:21 pm »
+1
Hi, I don't understand the answer to q3bii from the 2017 bio exam, was wondering if anyone could help? Much appreciated.

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Re: VCE Biology Question Thread
« Reply #12117 on: October 23, 2019, 10:28:39 am »
+2
Hey everyone,
I was just wondering whether anyone knew where I could find some resources such as practise exams or practice questions maybe even videos that could help me ace my Unit 2 Biology exam. I know they could be really rare due to it being a year 11 subject but I still want to do well on it. Hopefully, someone could help me out? Thanks, everyone!

Hey!
I found the Amoeba sisters youtube channel to be quite helpful to understand concepts as they explain it in a very entertaining, funny but also educational way! Also, they have practice questions and worksheets on their website for you to consolidate your knowledge.

Another resource I would suggest is KhanAcademy. For me, doing their practice questions helped and also exposed me to some content I didn't know before. I used this resource for my first SAC.

From a quick google, I found this resource as well https://mrlewis-vcebiology.weebly.com/unit-2.html where there are files you can download with powerpoints. Might be helpful.

Also, do you have textbook for biology? If you do, it would be worth doing questions from the chapter reviews and marking them yourself or asking a teacher to mark it.

The Biology 1 2 Checkpoints is also good to do because they have relevant questions that have popped up in exams.

This was a random list I made from the top of my head. I hope this helps!

Quote
Hi, I don't understand the answer to q3bii from the 2017 bio exam, was wondering if anyone could help? Much appreciated
So, you know that Lovastin is a competitive inhibitor. Here, the HMG-CoA is the real substrate that binds to the HMG-CoA Reductase enzyme where they have a complementary shape to each other. When the HMG-CoA substrate binds to the enzyme, there is an increase in blood cholesterol.

So, you want there to be a higher concentration of Lovastin (the competitive inhibitor) so that it is more likely for the Lovastin to bind to the HMG Reductase enzyme due to successful collisions, rather than the normal HMG-CoA substrate from binding so that the cholesterol cannot be produced, thus resulting in a lower concentration of cholesterol.
You don't want the Lovastin concentration to be too low because it would be more likely for the normal HMG substrate to bind to the enzyme, resulting in cholesterol being produced and high cholesterol and we do not want that.

I hope this makes sense!
 :)
« Last Edit: October 23, 2019, 10:37:13 am by Evolio »
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Re: VCE Biology Question Thread
« Reply #12118 on: October 23, 2019, 05:28:02 pm »
+2
From the 2008 VCAA Exam 2, for question 17, I picked the answer D but the answer is B and I was wondering why and why it wouldn't be D? I knew for sure that the answer was either B or D though.
Nothing in the question tells you how many proteins they produce. Number of genes =/= number of proteins. Even if number of genes = number of proteins, there still isn't a clear correlation between genome size and number of genes - Humans and mice have a genome about 30 times larger than that of the flowering mustard plant but have slightly less genes.

From the 2011 Exam 2 short answer, question 7 c i, I wrote that DNA has a low mutation rate so differences cannot easily be seen but VCAA's answer said that it's because the DNA has degraded. Would my answer be valid?
No they wouldn't accept that. The point of this question isn't really about comparing DNA, they're asking you to use the specific situation. You can't compare it because the DNA has degraded, because it was too long ago - there won't be any useful DNA to compare.

From the 2007 Exam 1, question 3 c , I designed an experiment such that the beakers were exposed to temperatures in increasing increments like one beaker is exposed to 10 degrees, the other 20 degrees. Then a graph had to be constructed so you could see the enzyme activity and see if it was lower or higher enzyme activity. Although, I'm not sure if this is a valid experiment as you are not actively testing the 37 optimum temperature and comparing it to another temperature to see the comparison. So, I was wondering if my experimental design would be valid?
All you're testing is that "the optimal temperature would be expected to be much lower than that shown by catalase from humans." There's no need to test 37 specifically (although it would probably be easier if you were actually doing this experiment).
You'd have to also have some at 30 and 40 degrees, because you'd probably have more activity at 20 degrees than 10 (if it hadn't denatured by then) so just having those two won't show that the optimum temperature is lower.

From the 2007 Exam 2, question 2g, I'm a bit confused as what do the examiner reports mean when they say use a different gene loci? Does that mean that the DNA in the sample means all the DNA of the suspects? Because, I  wrote the answer of use another sample from the crime scene.
Using another sample won't give a different result. I think it's a bit weird that they've said that they're using a particular locus, given they seem to be implying that they've separated out one gene only to run. Normally I'd say the correct answer would be to use different restriction enzymes on the DNA, which VCAA may have accepted as a correct answer in this case.
You just have to use the context from the question for this though - They've said in the stem that those results are for one gene locus, which is why one of the suggested answers is to use a different gene locus.

Also, how do T cytotoxic cells destroy cells?
I know that they induce apoptosis but do they do anything else and how do they do that?
Tc cells release perforin and granzymes - perforin puts a hole in the cell membrane which allows the granzymes to enter, they're what causes the cellular cascade that activates various enzymes that kill the cell. Aside from maybe knowing the names of those two things and what they do, you don't really need to know anything else about how Tc cells specifically induce apoptosis.
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Re: VCE Biology Question Thread
« Reply #12119 on: October 23, 2019, 05:50:43 pm »
0
It's more complicated than you're taught in VCE. For the exam, just assume that channel proteins are only for facilitated diffusion, and that carrier proteins can be used for both - but if you get a question about active transport, talk about carriers not channels.
Protein channels are involved in facilitated diffusion, but I'm 99% sure that they're also involved in active transport. ;D
Correct! Channel proteins can be used only in facilitated diffusion as molecules move through it down its concentration gradient without ATP Input.
I believe it would be carrier proteins (which are a little bit different) which can be used for both active and passive transport. Clarification would be great on this point though.

thank you guys!


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