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July 24, 2019, 08:26:37 am

Author Topic: VCE Biology Question Thread  (Read 1269294 times)  Share 

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darkz

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Re: VCE Biology Question Thread
« Reply #10470 on: June 13, 2018, 08:14:49 pm »
+1
Does it really block it from binding to the promoter region though? Cause the repressor protein binds to the operator, which is on the right of the promoter. So isn't it more correct to say that the repressor prevents it from moving along the structural genes?

See photo attached.

Well at a VCE level, I'm pretty sure that you can just say that because the repressor binds to the operator blocking RNA polymerase from binding to the promoter, therefore it is unable to move along the structural genes.
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Scribe

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Re: VCE Biology Question Thread
« Reply #10471 on: June 13, 2018, 08:23:03 pm »
0
Could someone list the specific steps in translation that would be approved by VCAA? Thanks as always :D

darkz

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Re: VCE Biology Question Thread
« Reply #10472 on: June 13, 2018, 08:27:12 pm »
+1
Could someone list the specific steps in translation that would be approved by VCAA? Thanks as always :D

Hey, I've attached a picture of a past vcaa exam answer for translation
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luccci

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Re: VCE Biology Question Thread
« Reply #10473 on: June 15, 2018, 02:15:46 pm »
0
Just on the topic of SACs and ranking I'm a little confused about the whole concept. I'm looking to get a 45+ for bio (I'm yr 11 doing 3/4) and my sac results have being 94%, 96%, 80% and 94%. My cohort is pretty strong especially a few other yr 11's. How will my ranking effect my study score and roughly how well would I need to perform on the exam in order to obtain a 45+?

Bri MT

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Re: VCE Biology Question Thread
« Reply #10474 on: June 15, 2018, 02:28:30 pm »
+1
Just on the topic of SACs and ranking I'm a little confused about the whole concept. I'm looking to get a 45+ for bio (I'm yr 11 doing 3/4) and my sac results have being 94%, 96%, 80% and 94%. My cohort is pretty strong especially a few other yr 11's. How will my ranking effect my study score and roughly how well would I need to perform on the exam in order to obtain a 45+?

Hey,

Welcome to atarnotes :)

There are some really great threads explaining how study scores are calculated and how to predict your own in the Victorian Technical Score Discussion section of the forum, here's a brief overview:
-VCAA cares about your rank and how well your cohort does on the exam, which is used to determine your SAC scores
- if you are rank 1 (highest SAC scores for bio at your school),  the best exam score from your school will replace/become your SAC marks
- 45+ is roughly the top 2% of the state,  so the marks needed for this will depend on how everyone else goes. Usually for bio you can lose several marks on the exam and stay in the 45+ range
- the exam is worth 60% of your study score,  but IF you're rank 1 AND get the best exam score that effectively means the exam is worth 100%, as whatever you get on the exam will become your SAC marks
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peachxmh

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Re: VCE Biology Question Thread
« Reply #10475 on: June 16, 2018, 02:07:35 pm »
0
Regarding the write up of an experiment, in a methodology how would you recommend writing out the steps in the method? Is it preferable to write out the steps in bullet points (e.g. - Place 3 algal balls in each test tube) or in past tense in a paragraph (e.g. 3 algal balls were placed in each test tube)? This may seem a little pedantic but I am quite curious as I would like to improve my expression in this area and my teacher hasn't given a definite answer.

Also, does a methodology usually contain a list of materials or just the method? If the method was written in past tense form would you still have to write out a separate list of the materials?

Thank you!
« Last Edit: June 16, 2018, 02:12:09 pm by peachxmh »
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PopcornTime

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Re: VCE Biology Question Thread
« Reply #10476 on: June 16, 2018, 06:47:51 pm »
+2

Regarding the write up of an experiment, in a methodology how would you recommend writing out the steps in the method? Is it preferable to write out the steps in bullet points (e.g. - Place 3 algal balls in each test tube) or in past tense in a paragraph (e.g. 3 algal balls were placed in each test tube)? This may seem a little pedantic but I am quite curious as I would like to improve my expression in this area and my teacher hasn't given a definite answer.

Also, does a methodology usually contain a list of materials or just the method? If the method was written in past tense form would you still have to write out a separate list of the materials?

Thank you!

You are right, definitely do the method in past tense, for example:

1. 30ml of amylase stock solution and 15ml of starch solution were measured using two separate measuring cylinders and both were added into two separate 100ml beakers
2. The beaker containing amylase solution was  incubated at 30°C for 10 minutes
Etc etc

Methodology is a broad category of method (above) and materials (100ml beaker, 15ml starch solution), so you can have them separately.

You can improve expression for method questions by doing the Design an experiment questions from VCAA exams. An example of these types of questions include:

Design an experiment to test the hypothesis that increasing temperature of the lactase solution will increase the rate of lactose breakdown.


Monkeymafia

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Re: VCE Biology Question Thread
« Reply #10477 on: June 16, 2018, 08:58:55 pm »
0
I understand that B and T cells mature, but how do they exactly mature? Is it just addition of the membrane bound receptors or something else chemically inside the cell?

darkz

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Re: VCE Biology Question Thread
« Reply #10478 on: June 16, 2018, 09:01:05 pm »
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I understand that B and T cells mature, but how do they exactly mature? Is it just addition of the membrane bound receptors or something else chemically inside the cell?

Yes, you're quite right! We consider B & T cells to be mature when they develop their respective receptors.
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TheBigC

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Re: VCE Biology Question Thread
« Reply #10479 on: June 17, 2018, 02:49:30 am »
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Yes, you're quite right! We consider B & T cells to be mature when they develop their respective receptors.

I will have to intercept here. Maturation of B and T cells involves negative and positive selection. They are not mature once they acquire specific B-cell or T-cell receptors (although this is obviously an important step in the maturation), only once they become self-tolerant are they mature.
« Last Edit: June 22, 2018, 09:22:48 pm by TheBigC »

TheAspiringDoc

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Re: VCE Biology Question Thread
« Reply #10480 on: June 17, 2018, 07:50:06 am »
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ribosomes should be enough.

Saying ribosomes in the cytoplasm discounts translation occuring in the RER so just saying ribosomes would be more appropriate.
But isn’t the RER part of the cytoplasm? Did you mean “cytosol would discount translation occurring at the RER”?
Because I thought cytoplasm = cytosol + non-nuclear organelles (e.g., includes RER?)

darkz

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Re: VCE Biology Question Thread
« Reply #10481 on: June 17, 2018, 06:23:21 pm »
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I will have to intercept here. Maturation of B and T cells involves clonal selection. They are not mature once they acquire specific B-cell or T-cell receptors (although this is obviously an important step in the maturation), only once they become self-tolerant are they mature.

Correct me if I'm wrong, but I thought that B or T cells are clonally selected after maturation and migration to the lymph node where they bind with an antigen and are then called 'selected' or 'activated' B & T cells and subsequently they undergo clonal expansion and they differentiate and proliferate? Or is that considered a part of the maturation process?
« Last Edit: June 17, 2018, 06:27:07 pm by darkdzn »
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Globe

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Re: VCE Biology Question Thread
« Reply #10482 on: June 17, 2018, 06:49:07 pm »
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Just some questions I need to get out. Do macrophages and dendritic cells (or any APC) travel to the lymph nodes in their entirety?

Also, if a macrophage engulfs an antigen and then presents it on its MHC Class 2 marker, does a subsequent B cell then also engulf the same antigen and present it on its MHC 2 marker (in order to start the humoral response)

Finally, when referring to B cell receptors, is it enough to call them just that, B cell receptors? Or must you say immunoglobulins.

Thanks :)
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PopcornTime

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Re: VCE Biology Question Thread
« Reply #10483 on: June 17, 2018, 10:04:34 pm »
+2
Just some questions I need to get out. Do macrophages and dendritic cells (or any APC) travel to the lymph nodes in their entirety?

I'll need confirmation from one of the other forum users: macrophages engulf and process the antigenic fragments and then travel to the lymph nodes, because thats where B and T cells reside after maturation. What do you mean by in their entirety?

Also, if a macrophage engulfs an antigen and then presents it on its MHC Class 2 marker, does a subsequent B cell then also engulf the same antigen and present it on its MHC 2 marker (in order to start the humoral response).

Not too sure about this. I got taught that the macrophage presents antigenic fragments to a helper T cell, who presents the antigen to a naive B cell and secretes cytokines to trigger the naive B cell to differentiate and proliferate, etc.

Finally, when referring to B cell receptors, is it enough to call them just that, B cell receptors? Or must you say immunoglobulins.
B cell receptors is fine

Thanks :)

Hope that helps.

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Re: VCE Biology Question Thread
« Reply #10484 on: June 18, 2018, 04:24:09 pm »
+2
Correct me if I'm wrong, but I thought that B or T cells are clonally selected after maturation and migration to the lymph node where they bind with an antigen and are then called 'selected' or 'activated' B & T cells and subsequently they undergo clonal expansion and they differentiate and proliferate? Or is that considered a part of the maturation process?
He will probably have to qualify what he meant here because I’m not entirely sure. T and B cells mature in the thymus/bone marrow where they’re tested for self reactivity (and some weird things happen with their receptors) they end up with the correct receptor (either CD4 or CD8) and (hopefully) not react to self antigens. Then they’re mature and they enter general circulation. They’re called naive until they bind their antigen though (maybe that’s what TBC meant?) but they don’t get clonally selected until after they mature.


Quote
Just some questions I need to get out. Do macrophages and dendritic cells (or any APC) travel to the lymph nodes in their entirety?
I’m not really sure what you mean by in it’s entirety but basically you have the APC, with fragments of a pathogen inside it that travels to the lymph node and presents those fragments on MHC2.

Quote
Also, if a macrophage engulfs an antigen and then presents it on its MHC Class 2 marker, does a subsequent B cell then also engulf the same antigen and present it on its MHC 2 marker (in order to start the humoral response).
Yes. A B cell will bind to a free antigen (so one that’s just floating around, not presented on anything) and if it can bind to it, it will engulf it (whereas macrophages don’t have to be able to bind to it) and then present it to a Th cell. Also it can happen in either order.


Quote
Not too sure about this. I got taught that the macrophage presents antigenic fragments to a helper T cell, who presents the antigen to a naive B cell and secretes cytokines to trigger the naive B cell to differentiate and proliferate, etc.
This does all happen but the B cell has to have found its antigen before it finds the Th cell and the cytokines trigger differentiation and proliferation in both the B cell and Th cell.
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