VCE Biology Question Thread

[chickennugget]

That question was from 2002, so I'm not sure if it's still relevant (it's probably not). Here's the answer for those wondering:

[vox nihili]

Yes that is correct, perfectly fine. 

That is true, injecting antigens into someone who has allergies is not beneficial because upon the first injection, the stimulation is the increased amount of B cell production, hence more antibodies are secreted and more mast cells are produced (since antibodies are embedded onto the mast cells). Because there are more B memory cells, then the second invasion of this antigen will cause a more intense and hypersensitive response, as the B cells will detect the antigen more quickly with more of an efficient response, and hence more antibodies will be secreted and bound on the membrane of mast cells, leading to degranulation of histamine upon antigen-antibody binding on mast cells. Usually you would want more memory B cells to fight off antigens more quickly upon second invasion, but with allergies, its not always the case. So yes, it will make it worse for the person.

Not always the case, think about when the antigen occurs naturally through intake of an allergic particle, why would there still be an allergic reaction if no IgE antibodies are produced? Thing is, different B cells produce different antibodies, very complex process/differentiation - not required for VCE

I'm reluctant to get into the details of why this is the case—because it's well beyond VCE—but these answers are incorrect.

The document chickennuget provides right above this gives a nice basic explanation as to why "vaccinating" against allergies is actually worthwhile.


Beyond VCE: because I know you'll be interested, cosine, the whole idea basically rests upon the fact that IgE is bad, as you mentioned, but IgG is good. Which particular antibody is produced in response to the antigen depends on a number of factors. Injecting the antigen skews towards the development of IgG antibodies. Allergens are normally encountered on mucosal surfaces, however, so you can imagine that that would be a very different environment immunologically speaking—and generally too—to blood, so it shouldn't be too much of a step to appreciate that the particular immune response to the allergen would be different and that that would involve a different class of antibodies being produced.
Happy to go into more detail if you're not satisfied, but that captures the essence of it

[cosine]

I'm reluctant to get into the details of why this is the case—because it's well beyond VCE—but these answers are incorrect.

The document chickennuget provides right above this gives a nice basic explanation as to why "vaccinating" against allergies is actually worthwhile.


Which particular antibody is produced in response to the antigen depends on a number of factors. Injecting the antigen skews towards the development of IgG antibodies.

Yeah this part is what I was clarifying from the post before. They said that IgG antibodies are produced upon natural infection of the allergen, however IgG and IgE antibodies are produced, it depends on various factors of the B cell's DNA.

Injecting the antigen skews towards the development of IgG antibodies. How do you know this though? Whats the difference between injecting antigens and producing IgG antibodies, and naturally attaining the allergen and producing both IgG and IgE?

[anniebrejcha]

hi!!

i have a few queries.
firstly; what do suppressor t-cells do? i'd pressume that they suppress a specific immune response, but i havent come across them before.

also! would someone be able to explain what would happen if helper t-cells weren't produced during a specific immune response?
i have a rough idea but i would appreciate a further understanding.

thanks in advance guys!

[cosine]

hi!!

i have a few queries.
firstly; what do suppressor t-cells do? i'd pressume that they suppress a specific immune response, but i havent come across them before.

also! would someone be able to explain what would happen if helper t-cells weren't produced during a specific immune response?
i have a rough idea but i would appreciate a further understanding.

thanks in advance guys!

Suppressor T cells suppress the immune response. For VCE, thats the most you need to know, and honestly, these cells hardly ever come up but just remember that they regulate/suppress the activity of the immune system.

Firstly, helper T cells are not 'produced' they are activated. Helper T cells already exist but just need to be activated by the correct APC. So I assume that you mean what happens if they are not activated? Well, then that means that the B cells cannot also be activated, since they require helper T cells to proliferate, and hence no memory/long term immunity is stored, and no immediate immunity occurs.

[anotherworld2b]

Hello
I had a question
We have been assigned to design your own practical for human bio:

Using your studies in Human Physiology from the material covered in the course, design an experiment that will investigate the following question.

What effect does the intake of ______ have in the rate of human urine production?
*suggested variable: cola, salt water, coffee, tea

But I can't think of a good method 
I'm not sure how to approach this task and how to test the variables correctly taking into consideration diet and ect
please help

[vox nihili]

Yeah this part is what I was clarifying from the post before. They said that IgG antibodies are produced upon natural infection of the allergen, however IgG and IgE antibodies are produced, it depends on various factors of the B cell's DNA.

Injecting the antigen skews towards the development of IgG antibodies. How do you know this though? Whats the difference between injecting antigens and producing IgG antibodies, and naturally attaining the allergen and producing both IgG and IgE?

Well beyond VCE

The particular type of antibody produced in response to an antigen is a product of time and the environment in which the B-cell encounters the antigen. Different cytokines, from T-cells in particular but also from other cells, skew towards the elaboration of particular antibodies.
So basically when you encounter an allergen naturally, it's in an environment that does skew towards IgE production; whereas when they're injected the environment is completely different and B-cells produce IgG in response instead.

That's a fairly simplified version of it, but I think should be a satisfactory explanation of why there is a difference. One thing you'll notice if you continue on with immuno is that immune reactions are really context dependent and involve a lot more than the linear diagrams in textbooks would suggest.

[Synchronised123]

greetings! Quick question: what does the term 'vascular' mean. Thanks in advance!

[Calebark]

Hi, Synchronised123. It just means that it pertains to vessels, such as blood vessels (arteries, veins, capillaries) or those of a plant (xylem, phloem).

[blacksanta62]

Hey, can anyone help me with these question please. It's part of my research SAC:
1) "Normally babies are not given their vaccination until they are old enough to have lost their first immunity. Why would a high antibody level in a baby interfere with the effectiveness of the vaccine?" (3 marks)
I'm not sure how to answer this question. Maybe I'm not researching properly?

Thank you

[vox nihili]

Hey, can anyone help me with these question please. It's part of my research SAC:
1) "Normally babies are not given their vaccination until they are old enough to have lost their first immunity. Why would a high antibody level in a baby interfere with the effectiveness of the vaccine?" (3 marks)
I'm not sure how to answer this question. Maybe I'm not researching properly?

Thank you

Hands down probably the most poorly written question I've seen in VCE.

What I suspect it's referring to is the passive immunity that comes from the mother. These antibodies would mop up the vaccine before the baby's immune system has an opportunity to respond.

[blacksanta62]

Thank you so much T-Rav. Really had me stumped. Do you think this is also an appropriate response:

As babies already have high levels of maternal antibodies for the first few months of their life (passive natural acquired immunity) attempting to induce an immune response wouldn't be successful because:
The babies immune system hasn’t developed and is immature. These maternal antibodies act as a shield, combating any antigens without the proliferation of B-cells thus evading the point of vaccines; to gain ‘memory’ of antigens through a primary antibody response
??

And I to put what you suggested into the research PowerPoint: such high levels of maternal antibody would help to dispose of the vaccine before an immune response has been elicited
Is that all I need to mention? It's a weirdly written question
 

Thank you

[vox nihili]

Thank you so much T-Rav. Really had me stumped. Do you think this is also an appropriate response:

As babies already have high levels of maternal antibodies for the first few months of their life (passive natural acquired immunity) attempting to induce an immune response wouldn't be successful because:
The babies immune system hasn’t developed and is immature. These maternal antibodies act as a shield, combating any antigens without the proliferation of B-cells thus evading the point of vaccines; to gain ‘memory’ of antigens through a primary antibody response
??

And I to put what you suggested into the research PowerPoint: such high levels of maternal antibody would help to dispose of the vaccine before an immune response has been elicited
Is that all I need to mention? It's a weirdly written question
 

Thank you

It could probably be written a little better.

I'll try to explain more clearly. Because you have maternal antibodies in the baby, whenever the baby encounters an antigen, these maternal antibodies will bind the antigen before the baby's B-cells have a chance. THerefore, you don't produce an immune response against those antigens because the baby's immune system doesn't encounter them.

[chickennugget]

I have a couple of VCAA questions that I would like explained. The examiner's report does not include any explanation. The black circle represents my answer, while the green represents the correct answer. Thanks

[vox nihili]

I have a couple of VCAA questions that I would like explained. The examiner's report does not include any explanation. The black circle represents my answer, while the green represents the correct answer. Thanks

IgM can't cross the placenta, so it has to have been produced by the baby. If the baby is producing anti-rubella IgM, then it has to have been infected by the virus in utero, because it would only produce such antibodies if it were exposed.
Tricky question. I'm sure it was poorly answered by most?

Agglutination just means that the red blood cells clump together because they've been bound by antibodies.

Someone with type O blood has antibodies to A and B
Someone with type A has antibodies to B
Someone with type B has antibodies to A
Someone with type AB has antibodies to no other blood group

Just to be sure, the O antigen isn't really in itself an antigen. O refers to the absence of A or B antigens on the surface of blood cells*

So if you added B antibodies to AB blood, that would bind the B antigen in that blood, which would agglutinate. If you added antibodies of type A to type O blood, what would it bind? There's no A antigen there.


*Beyond VCE: for the pedants: O blood type does technically have the H-antigen, but that just complicates the explanation