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March 29, 2024, 12:20:26 am

Author Topic: VCE Biology Question Thread  (Read 3570526 times)  Share 

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pmmenotes

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Re: VCE Biology Question Thread
« Reply #9405 on: October 15, 2017, 03:56:07 pm »
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Can someone help me with this question?



Approach 2 Single-celled algae from the coral reef are exposed to mutagens within a laboratory setting. Some of these algae are reintroduced back into the coral reefs.

What would be the purpose of exposing the single-celled algae to mutagens? 1 mark       

LifeisaConstantStruggle

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Re: VCE Biology Question Thread
« Reply #9406 on: October 15, 2017, 04:07:11 pm »
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This is the northern hemisphere question yeah. I got this marked by an assessor and got a correct answer:

Inducing a genetic mutation within the genome of the single-celled algae, so they would have beneficial mutations (by chance) that would prevent them from leaving the corals, which reduces the rate of bleaching.
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pmmenotes

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Re: VCE Biology Question Thread
« Reply #9407 on: October 15, 2017, 04:24:26 pm »
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This is the northern hemisphere question yeah. I got this marked by an assessor and got a correct answer:

Inducing a genetic mutation within the genome of the single-celled algae, so they would have beneficial mutations (by chance) that would prevent them from leaving the corals, which reduces the rate of bleaching.


Yeah its the NHT one but i didnt have any solutions thanks heaps that makes sense now!

ezferns

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Re: VCE Biology Question Thread
« Reply #9408 on: October 17, 2017, 08:37:00 pm »
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Would nuances between carrier proteins and channel proteins make a difference on the exam? I've seen in third party exams and the internet that glucose diffuses via carrier proteins but the 2014 vcaa exam says channel proteins. Would writing carrier proteins lose me the mark?

Sine

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Re: VCE Biology Question Thread
« Reply #9409 on: October 17, 2017, 08:40:50 pm »
+1
Would nuances between carrier proteins and channel proteins make a difference on the exam? I've seen in third party exams and the internet that glucose diffuses via carrier proteins but the 2014 vcaa exam says channel proteins. Would writing carrier proteins lose me the mark?
I don't think vcaa distinguish between channel and carrier proteins. Just make sure to know the difference between facilitated diffusion and active transport

Not directly related: the assesor report doesn't always have all the possible answers to the question
« Last Edit: October 17, 2017, 08:43:39 pm by Sine »

vox nihili

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Re: VCE Biology Question Thread
« Reply #9410 on: October 17, 2017, 08:44:52 pm »
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Would nuances between carrier proteins and channel proteins make a difference on the exam? I've seen in third party exams and the internet that glucose diffuses via carrier proteins but the 2014 vcaa exam says channel proteins. Would writing carrier proteins lose me the mark?

Better yet, you could just say it diffuses by facilitated diffusion and not have to worry about carriers or channels.

The reality is that there really aren't any hard and fast rules about what uses a carrier protein and what uses a channel and certainly you wouldn't be expected, as Sine said, to make any comment on that in a VCE exam.
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Sine

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Re: VCE Biology Question Thread
« Reply #9411 on: October 17, 2017, 08:48:12 pm »
+1
Better yet, you could just say it diffuses by facilitated diffusion and not have to worry about carriers or channels.

The reality is that there really aren't any hard and fast rules about what uses a carrier protein and what uses a channel and certainly you wouldn't be expected, as Sine said, to make any comment on that in a VCE exam.
just checked the 2014 exam it was a 2 marker question so definitely had to suggest either protein channel/carrier protein

JamesGilson

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Re: VCE Biology Question Thread
« Reply #9412 on: October 18, 2017, 10:21:05 am »
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Can someone please tell me how B and T cells are activated, the answers my teacher and the exams give are so ambiguous  :'(

PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9413 on: October 18, 2017, 12:50:11 pm »
+3
B cells are activated by free antigens (ie parts that have broken off) binding to them. T helper cells are activated by an antigen that they can bind to being presented to them on MHC 2 markers by an Antigen Presenting Cell (APC) ie. dendritic cells and macrophages.The activated B cells and T helper cells then find each other and if they have the same specificity (have bound the same antigen) the T helper cell will release cytokines (a type of signalling molecule) that further stimulate both of them to divide and differentiate. Cytotoxic T cells are activated when they can bind to a peptide fragment presented on an mhc 1 molecule. They can also be further stimulated by the cytokines but do not need to interact with t helper cells.
« Last Edit: October 18, 2017, 01:12:49 pm by PhoenixxFire »
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vox nihili

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Re: VCE Biology Question Thread
« Reply #9414 on: October 18, 2017, 12:53:55 pm »
+2

B cells are activated by free antigens (ie parts that have broken off) binding to them. T helper cells are activated by an antigen that they can bind to being presented to them by an Antigen Presenting Cell (APC) ie. dendritic cells and macrophages. The activated B cells and T helper cells then find each other and if they have the same specificity (have bound the same antigen) the T helper cell will release cytokines (a type of signalling molecule) that further stimulate both of them to divide and differentiate. Cytotoxic T cells are activated when they can bind to a peptide fragment presented on an mhc 1 molecule. They can also be further stimulated by the cytokines but do not need to interact with t helper cells.

Don’t forget to mention that T helper cells bind to antigen in MHC class II molecules, which are on the APCs :)
Really pedantic, but worth marks. This is otherwise perfect.
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #9415 on: October 18, 2017, 01:08:07 pm »
+2
Haha thanks vox! I did mean to but I'm on a school excursion and i had to wait until our lunch break (now) and my friends are trying to talk to me (but AN is more important 8))

Have updated previous post to include that.
« Last Edit: October 18, 2017, 01:10:38 pm by PhoenixxFire »
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ezferns

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Re: VCE Biology Question Thread
« Reply #9416 on: October 18, 2017, 10:23:34 pm »
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Can someone pls explain to me multiple choice questions 17 and 40 on the vcaa 2014 exam?
For 17 why can't it be d?
For 40 why can't it be a?

ezferns

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Re: VCE Biology Question Thread
« Reply #9417 on: October 18, 2017, 10:25:24 pm »
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Also how do you know when to talk about clonal selection being activated by a B cell detecting a specific raw antigen or when clonal expansion is initiated by a specific T helper cell stimulating an activated B cell?

LifeisaConstantStruggle

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Re: VCE Biology Question Thread
« Reply #9418 on: October 18, 2017, 10:30:20 pm »
+1
Can someone pls explain to me multiple choice questions 17 and 40 on the vcaa 2014 exam?
For 17 why can't it be d?
For 40 why can't it be a?

17) Invading host cell or host cell DNA? It seems that b would be the more accurate answer here
40) the other great apes (hominids) have opposable thumbs as well. (C would be the answer)

Also how do you know when to talk about clonal selection being activated by a B cell detecting a specific raw antigen or when clonal expansion is initiated by a specific T helper cell stimulating an activated B cell?

I tend to mix both together (not sure if it's right? but I've been getting full marks for immunity questions that describe the action of a vaccine)
- T helper cells release cytokines to stimulate the clonal expansion of clonal selected naive B cells which detect specific antigens as non-self, which divides and differentiates to form antibody-producing B plasma cells, and B memory cells......(continue)
« Last Edit: October 18, 2017, 10:39:43 pm by LifeisaConstantStruggle »
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ezferns

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Re: VCE Biology Question Thread
« Reply #9419 on: October 19, 2017, 07:06:28 am »
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Oh shit sorry I meant vcaa 2013 😬
Thanks for your answer!