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Author Topic: VCE Biology Question Thread  (Read 3571030 times)  Share 

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Erutepa

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Re: VCE Biology Question Thread
« Reply #11775 on: June 20, 2019, 11:16:20 pm »
+14
Couple of questions for immunity:
Would I be correct in saying dendritic cells process antigenic material and display their antigens on their MHC 2 markers for T helper cells to recognise, thus providing a link to the adaptive immune response. Is it specifically targeting T helper cells or other leukocytes as well?

This is good! Although I would specify that dendritic cells present pathogenic/non self antigens on the mhc class 2 receptors. Realistically dendritic cells do present not just pathogenic antigens, but as far as our course is concerned, dendritic cells just present pathogenic antigens.
Realistically dendritic cells will bind to other cells like cytotoxic T cells and what not, but these specifics aren't relevant to the course. Just know that they bind to the t helper cell as you have mentioned.

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Am I right in saying MHC 1 markers displays antigens produced by the presenting cell whereas MHC 2 markers displays nonself antigens outside the presenting cell?

Yes. This sounds right!

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How would one describe how a person produces more antibodies during secondary exposure to specific antigen than the first exposure (basically how would I explain memory B cells and how they develop immunological memory - just looking for a more concise explanation than the one I have)

As a result of a primary immune response, memory b cells specific to the antigen illiciting this response are produced. These memory b cells exist in a greater number relative to that of the nieve cells in a primary infection such that secondary infections are characterised by a faster and greater antibody production.
Basically, because of memory b cells, there are more cells that can potentially bind to the antigen and be activated by t helper cells such that the immune response occurs faster and to a greater extent.
Does this help?
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How specifically does inflammation response benefit the immune response? Do I just need to say it attracts phagocytes and large molecules to site of infection helping develop a rapid innate response via physiological changes.

The inflammation response involves many different aspects which all contribute to the immune response. It's not just the case that inflammation involves the release of cytokines which attract other immune cells to the region of infection, but this is certainly one major part of the inflammation response. You could use that as an answer. You could also talk about the vasodilation and adaptations to the local vasculature that enable the migration of immune cells.
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MHC 1 and 2 markers are all proteins, all antibodies are proteins, not all antigens are proteins, all MHC 2 markers are made of antibodies - is my understanding correct?

This is correct except mhc class 2 receptors are not antibodies. You might be thinking about b cell receptors which are surface bound antibodies.

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Why would a vaccine that contains the pathogen in an inactivated form be less effective than one where it is in an weakened form? I'd assume because since its dead it elicits a weaker adaptive immune response and weaker immunological memory but need someone to expand on this please

Not entirely sure about this, but your reasoning seems quite sound. Remember that an immune response is illicited by the sensing of damage and/or danger from the immune system. If the virus is completely inactive it won't cause damage and thus has a much lower chance of Illiciting an immune response
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In multiple sclerosis, the B and T cells are involved in targeting the myelin sheathe of neurons as a result of failure of self-tolerance. Is it also due to mitochondria in oligodendrocytes breaking down that leads to destruction of myelin sheathe? If the second part is true do I have to mention this?(just feels like its out of the study design and not required)

You are right. This is out of the study design and you do not need to know this.
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How much do we need to know about types of pathogens such as prions and worms, I know their names but what features should I know about them?

You don't need to know much. This content is usually examined through questions asking you to simply identify the pathogen from basic characteristics. So just know the key features of each one. You don't need the specifics of how they function. Hobestly worms, virions, prions and fungi are not all That prevelant, atleast from my own experience. The main thing is understanding and being able to differentiate between viruses and bacteria.
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¡
Are T helper cells activated by antigen presenting cells specifically macrophages and dendritic cells or can they be activated by cells that display nonself antigens on their MHC 1 markers?
Thanks in advance :D
Must be by mhc class 2 markers, thus must be by a macrophage or dendritic cell.
« Last Edit: June 20, 2019, 11:21:57 pm by Erutepa »
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FrankieDens

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Re: VCE Biology Question Thread
« Reply #11776 on: June 21, 2019, 02:37:09 pm »
0
Hi everyone!

I just finished my Unit 3 Outcome 2 SAC (the cell communication one) and overall it was great but one question really stumped me. Basically a pregnant horse was vaccinated and a graph of the foal's antibody concentration is included. At the beginning, the concentration is pretty high but it decreases until at 3 months old where there are 0 antibodies left.

I don't remember the exact wording of the question but it basically asks why it would be ineffective to vaccinate the foal before 3 months old. Is it because it still relies on its naturally (acquired) passive immunity?
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Re: VCE Biology Question Thread
« Reply #11777 on: June 21, 2019, 02:44:38 pm »
+4
Yeah that’s basically it, their immune system isn’t developed at that point. If you give them a vaccination whilst they have antibodies, those antibodies will neutralise the antigenic fragments in the vaccine and the foals own immune system won’t have a chance to react to it, and therefore won’t generate memory cells and therefore no immunity.
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caffinatedloz

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Re: VCE Biology Question Thread
« Reply #11778 on: June 21, 2019, 03:08:14 pm »
0
Hey guys, just a couple of quick questions that I would appreciate some clarification with: (Unit 1)
1. How is information transmitted from the receptor to the control centre?

2. If someone has Type 1 diabetes will their blood glucose levels increase or decrease overnight. Why?

Matthew_Whelan

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Re: VCE Biology Question Thread
« Reply #11779 on: June 21, 2019, 03:32:20 pm »
+4
Hey guys, just a couple of quick questions that I would appreciate some clarification with: (Unit 1)
1. How is information transmitted from the receptor to the control centre?

2. If someone has Type 1 diabetes will their blood glucose levels increase or decrease overnight. Why?

1. It depends on the pathway, eg  a external stimulus will be received at a receptor on the body which will transmit the info via neurons (electrochemical process) whereas other pathways could be a cell receiving a signal to elicit an intracellular response (encode RNA, undergo apoptosis); this is signal transduction.

2. Type 1 diabetes causes a deficiency of insulin production in the pancreas which causes the person's blood glucose levels to be abnormally high, so it would increase overnight I believe.

If I got something wrong pls point it out ;)

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Rom_Dog

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Re: VCE Biology Question Thread
« Reply #11780 on: June 22, 2019, 10:10:34 am »
+6
Hey guys, just a couple of quick questions that I would appreciate some clarification with: (Unit 1)
1. How is information transmitted from the receptor to the control centre?

2. If someone has Type 1 diabetes will their blood glucose levels increase or decrease overnight. Why?

Hey!

Matthew is right in saying type 1 diabetes is associated with a deficiency in insulin production however sugar levels remain abnormally high after meals as insulin is in low levels or absent, insulin lowers blood glucose by promoting the uptake of glucose by the body's cells (especially the liver and muscles where glycogen, the a highly branched polymer of glucose is produced and stored).

Over night blood glucose slowly decreases as it is metabolised by the body but blood glucose levels still remain elevated in comparison to a healthy individual which you can see on the graph here

Hope this helps!

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caffinatedloz

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Re: VCE Biology Question Thread
« Reply #11781 on: June 22, 2019, 06:33:35 pm »
0
Hey!

Matthew is right in saying type 1 diabetes is associated with a deficiency in insulin production however sugar levels remain abnormally high after meals as insulin is in low levels or absent, insulin lowers blood glucose by promoting the uptake of glucose by the body's cells (especially the liver and muscles where glycogen, the a highly branched polymer of glucose is produced and stored).

Over night blood glucose slowly decreases as it is metabolised by the body but blood glucose levels still remain elevated in comparison to a healthy individual which you can see on the graph here

Hope this helps!

Thank you!!

f0od

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Re: VCE Biology Question Thread
« Reply #11782 on: June 22, 2019, 10:03:17 pm »
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Why is it difficult to produce an effective influenza (or other disease) vaccine?

Also, what are the three major categories of vaccines and what are the advantages & disadvantages of each type?

Thanks!!
« Last Edit: June 22, 2019, 10:22:10 pm by f0od »
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vox nihili

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Re: VCE Biology Question Thread
« Reply #11783 on: June 22, 2019, 10:46:06 pm »
+1
Why is it difficult to produce an effective influenza (or other disease) vaccine?

Also, what are the three major categories of vaccines and what are the advantages & disadvantages of each type?

Thanks!!

What do you think?

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Evolio

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Re: VCE Biology Question Thread
« Reply #11784 on: June 23, 2019, 10:15:57 am »
0
Quote
Second messengers are activated. Look at a diagram of signal transduction and note that the reception of the ligand by its specific protein receptor on the taget cell's surface induces a conformational change in the receptor. This shape change is what leads to the activation of second messengers. THese are present in inactive forms in the cell. I suspect there will be cases were these are produced, but this isn't really required info.

There might be cases where a second messenger activates a molecule which then splits into 2 parts, one of which is used later in the pathway, for example. Again, this is not required knowledge.

Your response is ok. Perhaps you might like to say that the cell responds by >>>sythesising proteins that allow... to occur<<<. This is not essential, from what I have seen, but it might be something you want to include.
Thank you DBA-144!

Hi guys.
Just had a few questions I wanted to ask.
1. What happens to the H + ions that are pumped into the intermembrane space? Like, where do they go? What are they used for?

2. Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the
stroma. This damage will have the most direct effect on which of the following processes?
a. the splitting of water
b. the absorption of light energy by chlorophyll
c. the flow of electrons from photosystem II to photosystem I
d. the synthesis of ATP
e. the reduction of NADP+
The answer is E. I think it's D because the ADP+ Pi produced from the light independent stage in the stream is combined to make ATP produced in the light dependant stage. But, I don't get why it's E.

Owlbird83

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Re: VCE Biology Question Thread
« Reply #11785 on: June 23, 2019, 10:25:55 am »
+3
Thank you DBA-144!

Hi guys.
Just had a few questions I wanted to ask.
1. What happens to the H + ions that are pumped into the intermembrane space? Like, where do they go? What are they used for?

The H+ ions build up so there is a high conc in the intermembrane space which means there is a concentration gradient, so the H+ ions want to travel out. They travel out through a channel where there is ATP synthase which is able to make ADP into ATP with the energy generated from the H+ ions leaving. The H+ ions are then taken by the carrier molecules NADP+ (forming NADPH) and carry them to the light independent stage where they drop them off to the Calvin cycle and the H+ ions enter and become part of the glucose (C6H12O6).

Sorry I'm not confident in answering your other question. Also if what I wrote is wrong, someone please correct me!  :D

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DBA-144

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Re: VCE Biology Question Thread
« Reply #11786 on: June 23, 2019, 11:00:53 am »
+4
Thank you DBA-144!

Hi guys.
Just had a few questions I wanted to ask.
1. What happens to the H + ions that are pumped into the intermembrane space? Like, where do they go? What are they used for?

2. Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the
stroma. This damage will have the most direct effect on which of the following processes?
a. the splitting of water
b. the absorption of light energy by chlorophyll
c. the flow of electrons from photosystem II to photosystem I
d. the synthesis of ATP
e. the reduction of NADP+
The answer is E. I think it's D because the ADP+ Pi produced from the light independent stage in the stream is combined to make ATP produced in the light dependant stage. But, I don't get why it's E.


1. Probably wrong but I don't think that the intermembrane space has any role in photosynthesis. What OwlBird83 has outlined is the general process of photosynthesis, where water molecules split into H+ and O2 --> H+ used to produce ATP and NADPH which are then used in the light independent stage. I don't think that the intermembrane space has any relevance for VCE students, but I am probably wrong. It's been a while since we did photosynthesis.

2. Not sure about this one tbh. But since this has no effect on aerobic respiration, I guess that ATP will still be produced. All of  the other options make no sense and hence it should be E. Basically, what is happening here is that the H+ ions can just move out of the thylakoid without >having< to pass thru any proteins, etc. and hence won't combine with electrons and NADP+ to form NADPH. However, I think that my reasoning for aerobic respiration would be wrong here. Nevertheless, ATP could still be produced as some of the H+ ions will be moving thru ATP synthase.

Can we expect to see such questions from vcaa? Is there an easier explanation to this hahaha?
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vox nihili

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Re: VCE Biology Question Thread
« Reply #11787 on: June 23, 2019, 11:18:59 am »
+4


1. Probably wrong but I don't think that the intermembrane space has any role in photosynthesis. What OwlBird83 has outlined is the general process of photosynthesis, where water molecules split into H+ and O2 --> H+ used to produce ATP and NADPH which are then used in the light independent stage. I don't think that the intermembrane space has any relevance for VCE students, but I am probably wrong. It's been a while since we did photosynthesis.

2. Not sure about this one tbh. But since this has no effect on aerobic respiration, I guess that ATP will still be produced. All of  the other options make no sense and hence it should be E. Basically, what is happening here is that the H+ ions can just move out of the thylakoid without >having< to pass thru any proteins, etc. and hence won't combine with electrons and NADP+ to form NADPH. However, I think that my reasoning for aerobic respiration would be wrong here. Nevertheless, ATP could still be produced as some of the H+ ions will be moving thru ATP synthase.

Can we expect to see such questions from vcaa? Is there an easier explanation to this hahaha?


I agree that both of these questions are probably a bit beyond a VCE level. We can safely ignore them.

Also agree with OP that D is perfectly reasonable as an alternative answer. Certainly beyond me why reduction of NADPH would be more relevant than synthesis of ATP, given the processes are effectively tied together.
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Evolio

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Re: VCE Biology Question Thread
« Reply #11788 on: June 23, 2019, 12:45:09 pm »
0
Thank you Owlbird83, DBA-144 and vox nihili!  :)

Also, for the first question I meant in relation to aerobic cellular respiration, not photosynthesis i.e intermembrane space in mitochondria. I just don't understand what happens to the H+ ions after the proton gradient is established.
Sorry for not being clear !

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Re: VCE Biology Question Thread
« Reply #11789 on: June 23, 2019, 01:18:37 pm »
+1
hi,
what is the difference between cytokines and cytotoxins?


2019 vce journal here