VCE Biology Question Thread

[Biology24123]

How accurate is the attached image regarding inflammation and fever? (Neap 2009 answer)

Few questions:

1. Describe one possible form of an effective equine influenza vaccine?
Can it be said that if the viral genome is removed, the virus is attenuated and is unable to infect, but still will induce an immune response?

2. Explain how the vaccine would lead to an immune response in a horse?
This is exactly what I wrote:

The attenuated viruses will be engulfed by phagocytes such as macrophages and the antigenic fragments presented on MHC II markers. Specific helper T cells recognise these markers and become activated, then these helper T cells activate cytotoxic T cells to proliferate into effector and memory T cells. B cells are also activated when they present the same antigen on their MHC II markers to helper T cells and proliferate into plasma and memory B cells.

Their answer is also attached (second image). They have nothing mentioned about Cytotoxic T cells, anyone know why? How would I know not to include T cells in the answer? Is it bad that I actually did? Also, they go on about antibody production and pathogen neutralisation, is this required to be stated in the answer? Because the question says how the vaccine would lead to an immune response, but once again why did they not mention the activity of T cells?

Not sure if you would lose marks for that but I know why they didn't mention it. Cytotoxic T cells destroy cells that are infected with the virus. This is a vaccine so no cells will be infected and cytotoxic T cells not needed.

For question 1. I believe that is right but you could also just have the antigen and not the rest of the virus

[cosine]

Not sure if you would lose marks for that but I know why they didn't mention it. Cytotoxic T cells destroy cells that are infected with the virus. This is a vaccine so no cells will be infected and cytotoxic T cells not needed.

That makes so much sense now, but T helper cells are definitely activated, and these activate cytotoxic T cells upon binding, so what ensures them not being activated? Because honestly, this is a vaccine, you would obviously want to have memory T cells so that when the virus actually invades, these memory T cells are available to actually kill the infected cells rapidly. Right or no? Thanks

[tashhhaaa]

Yeh, not specifically but be safe, on a MC once the question asked an example of first line defence mechanism:

A. Lysosomes
B. Lysozymes
C. Antibodies
D. Forgot this one

Obviously here you needed to know the different between lysosomes (organelles that fuse with phagosomes to destroy the pathogens in the second line of defence in phagocytes) and lysozymes (enzymes secreted in tears as a first line of defence that kill bacteria)

cheers 

[Biology24123]

That makes so much sense now, but T helper cells are definitely activated, and these activate cytotoxic T cells upon binding, so what ensures them not being activated? Because honestly, this is a vaccine, you would obviously want to have memory T cells so that when the virus actually invades, these memory T cells are available to actually kill the infected cells rapidly. Right or no? Thanks

This I think is one of the holes in the VCE course (correct me if i'm wrong Mr T Rav). Not sure about that question but maybe T helper cells recognise the type of pathogen (is this possible?)

[cosine]

This I think is one of the holes in the VCE course (correct me if i'm wrong Mr T Rav). Not sure about that question but maybe T helper cells recognise the type of pathogen (is this possible?)

Nah read online that Cytotoxic T cells are activated by T helper cells, and when they are activated they proliferate into memory and effector T cells that will destroy the virally infected cells. So I thought that because this is a virus, both the B cell proliferation and T cell proliferation will aid because memory T cells will aid in long term killing the virally infected cells and B cells will produce antibodies to neutralise the viruses in the second invasion.

So in essence, do we need to know anything about memory T cells? Or is this sample answer not clear enough. Like for example if a question asked this on a VCAA exam, would I lose marks if I also included the T cell part?

[Biology24123]

Nah read online that Cytotoxic T cells are activated by T helper cells, and when they are activated they proliferate into memory and effector T cells that will destroy the virally infected cells. So I thought that because this is a virus, both the B cell proliferation and T cell proliferation will aid because memory T cells will aid in long term killing the virally infected cells and B cells will produce antibodies to neutralise the viruses in the second invasion.

So in essence, do we need to know anything about memory T cells? Or is this sample answer not clear enough. Like for example if a question asked this on a VCAA exam, would I lose marks if I also included the T cell part?

Yeah I think we are overthinking it. I think for some reason they decided not to include the T cell part and you probably wouldn't lose marks for it. I will confirm it with someone

[vox nihili]

Cheers,

Can meiosis occur if an organism is monosomy ?

No

This I think is one of the holes in the VCE course (correct me if i'm wrong Mr T Rav). Not sure about that question but maybe T helper cells recognise the type of pathogen (is this possible?)

Vaccines are pretty complex and I won't pretend to know all of the details.

You are right though in saying that T-helper cells are actually able to recognise the type of pathogen. The response to an invader will depend on the type of invader. The immune response to a virus differs from the immune response to a bacterium, both of which differ from the immune response to a helminth. The details of this are completely irrelevant in the VCE course.

VCE knowledge: vaccines induce a B-cell response, more antibodies secondary exposure blah blah blah


Real life: different vaccines induce different responses. Some are good for B-cells, others are good for T-cells, some good for both.

[Biology24123]

No

Vaccines are pretty complex and I won't pretend to know all of the details.

You are right though in saying that T-helper cells are actually able to recognise the type of pathogen. The response to an invader will depend on the type of invader. The immune response to a virus differs from the immune response to a bacterium, both of which differ from the immune response to a helminth. The details of this are completely irrelevant in the VCE course.

VCE knowledge: vaccines induce a B-cell response, more antibodies secondary exposure blah blah blah


Real life: different vaccines induce different responses. Some are good for B-cells, others are good for T-cells, some good for both.

So when talking about vaccines, for the course we only talk about B cells?

[vox nihili]

So when talking about vaccines, for the course we only talk about B cells?

That's right

[cosine]

No

Vaccines are pretty complex and I won't pretend to know all of the details.

You are right though in saying that T-helper cells are actually able to recognise the type of pathogen. The response to an invader will depend on the type of invader. The immune response to a virus differs from the immune response to a bacterium, both of which differ from the immune response to a helminth. The details of this are completely irrelevant in the VCE course.

VCE knowledge: vaccines induce a B-cell response, more antibodies secondary exposure blah blah blah


Real life: different vaccines induce different responses. Some are good for B-cells, others are good for T-cells, some good for both.

Alright so will scratch T cells from vaccines then

Also is Memory T cells required for VCE man? Because study design does not say it but neither says it for B cells ?

[Biology24123]

Alright so will scratch T cells from vaccines then

Also is Memory T cells required for VCE man? Because study design does not say it but neither says it for B cells ?

You need to know that they are long living cells that remain in circulation and are specific to antigens that have been encountered. They proliferate when the antigen is encountered again etc...

[cosine]

You need to know that they are long living cells that remain in circulation and are specific to antigens that have been encountered. They proliferate when the antigen is encountered again etc...

So do we need to know they exist or not ? Like after a specific Cytotoxic T Cell is activated, it proliferates into effector and memory T cells. Do we need to know this? If not, what can be said instead, for example when we are asked to describe the cell mediated immunity ?

[Biology24123]

So do we need to know they exist or not ? Like after a specific Cytotoxic T Cell is activated, it proliferates into effector and memory T cells. Do we need to know this? If not, what can be said instead, for example when we are asked to describe the cell mediated immunity ?

You need to say they are produced. If you are asked what happens on the 2nd exposure you talk about memory cells

[cosine]

You need to say they are produced. If you are asked what happens on the 2nd exposure you talk about memory cells

How do we know about when to talk about memory B cells or memory T cells ?

[vox nihili]

Alright so will scratch T cells from vaccines then

Also is Memory T cells required for VCE man? Because study design does not say it but neither says it for B cells ?

I'd suggest not.

In the VCE course, the details of vaccination focuses on the B-cell response and the production of memory B-cells. In my view, you'd get full marks for talking about B-cells alone. That said, I have been wrong before!