VCE Biology Question Thread

[KingDrogba]

During both Humoral Immunity and Cell Mediated Immunity, both B and T Cells proliferate (clonal expansion), why does this occur?
Does it amplify the response?

Also, what is the difference between self and non-self antigens? Is it just that non-self will trigger and immune response because its foreign material and self antigens will be ignored because they belong???

Thank you!

[grannysmith]

During both Humoral Immunity and Cell Mediated Immunity, both B and T Cells proliferate (clonal expansion), why does this occur?
Does it amplify the response?

Also, what is the difference between self and non-self antigens? Is it just that non-self will trigger and immune response because its foreign material and self antigens will be ignored because they belong???

Thank you!

Yeah, pretty much. If you're cloning more B and T cells, you're going to cause a faster/greater response.

Yep, self molecules are ignored because they're not detected, since any immune cells which happen to be receptive to self molecules are destroyed. When this process of self tolerance fails, that's when you get your autoimmune diseases.

However, non self molecules are antigens which trigger an immune response.

[wobblywobbly]

Hey guys would you lose mark if you made a little misleading wording in a bio sac that is irrelevant to the answer? The question said state why the shape and structure of neurotransmitters is important in the transmission of electrical impulses.

I wrote "Because neurotransmitters are hormones, they have specific protein receptors on the postsynaptic membrane and in order to bind with them, to initiate an action potential in the adjacent neurone, the neurotransmitters need to be complementary with the receptors"

But neurotransmitters are not hormones, I got mixed up was supposed to say ligand or signalling molecule -.-.-.-

Yes anything wrong with your statement, regardless of anything else right you have said or anything contradictory will cost you marks. Just try and not write too much irrelevant stuff in your answers -- keep them concise and precise.

[vox nihili]

Hey guys would you lose mark if you made a little misleading wording in a bio sac that is irrelevant to the answer? The question said state why the shape and structure of neurotransmitters is important in the transmission of electrical impulses.

I wrote "Because neurotransmitters are hormones, they have specific protein receptors on the postsynaptic membrane and in order to bind with them, to initiate an action potential in the adjacent neurone, the neurotransmitters need to be complementary with the receptors"

But neurotransmitters are not hormones, I got mixed up was supposed to say ligand or signalling molecule -.-.-.-

Concur with everyone else, you'll probably drop a mark.

Just for interest's sake, some neurotransmitters can also be hormones.

[Sine]

My next sac is a Summary Poster on the Immune System done under test conditions. What should I be expecting to be responding to? If any one else has done this before any information would be helpful.

[kimmytaaa]

I have a sac on immune system and it is to be done as a pamphlet. The teacher said that we are given a specific disease to research on. So what am I expecting to know about?

[Jay.C]

Hey guys, just wondering do B-lymphocytes attach to phagocytes, since phagocytes display MHC class 2 markers? Also which cells are responsible for detecting foreign material?

[grannysmith]

Hey guys, just wondering do B-lymphocytes attach to phagocytes, since phagocytes display MHC class 2 markers? Also which cells are responsible for detecting foreign material?

Firstly, only T cells really bind to MHC II markers, and this is the only way in which T cells can detect antigens i.e. those expressed on MHC II markers.

Also, some B cells possess these MHC II markers, and can therefore be considered as APCs - which also include macrophages and dendritic cells. These are the only phagocytes which have MHC II. All other ones only have MHC I.

Pretty much all phagocytes and immune cells detect foreign material, but the method in which they are detected and the types of antigens is what differs between them.

[vaish_vj]

Hey,
Can someone please explain the steps that occur during an allergic response? i am really confused.   

[biy]

Do we need to know any specifics about the types of pathogens such as bacterias, viruses, viroids, prions etc..?

Also what is the difference between contagious diseases and infectious dieases?
I said that infectious diseases are diseases that are caused by pathogens that infect a certain organism or part of an organism, whereas a contagious disease can be passed on by an organism to organism.. Aren't they essentially the same thing anyway?

How much about viral infections do we need to know? Do we need to know about how viruses attach to their host cell, and how they penetrate the membrane and inject their viral nucleic acid and the steps from there?

Thank you a lot everyone <3

[grannysmith]

Hey,
Can someone please explain the steps that occur during an allergic response? i am really confused.   

A specific B cell encounters the allergen and binds to the antigen. With the aid of corresponding T-helper cells, the B cell proliferates and differentiates into plasma and memory B cells. These plasma B cells produce an abnormal amount of IgE antibodies, which bind to the surface mast cells found in the lining of blood vessels (among other places). Now, if the same allergen is encountered a second time, they can bind to these specific IgE antibodies on the surface of mast cells, triggering a response i.e. the degranulation of mast cells, releasing histamines which causes the constriction of blood vessels etc. and your typical allergic response ensues.

Do we need to know any specifics about the types of pathogens such as bacterias, viruses, viroids, prions etc..?

Also what is the difference between contagious diseases and infectious dieases?
I said that infectious diseases are diseases that are caused by pathogens that infect a certain organism or part of an organism, whereas a contagious disease can be passed on by an organism to organism.. Aren't they essentially the same thing anyway?

How much about viral infections do we need to know? Do we need to know about how viruses attach to their host cell, and how they penetrate the membrane and inject their viral nucleic acid and the steps from there?

Thank you a lot everyone <3

Yeah, you need to be able to distinguish between the different types of pathogens, their basic structure and their modes of infection, very briefly.

There's a slight difference, and what you've said pretty much sums it up.

re: viral infections, you only need to know that viruses infect by attaching to a host cell and injecting its viral nucleic acid, thereby overriding the host cell's own DNA and in effect, taking control of the cell's inner-machinery.

[biy]

A specific B cell encounters the allergen and binds to the antigen. With the aid of corresponding T-helper cells, the B cell proliferates and differentiates into plasma and memory B cells. These plasma B cells produce an abnormal amount of IgE antibodies, which bind to the surface mast cells found in the lining of blood vessels (among other places). Now, if the same allergen is encountered a second time, they can bind to these specific IgE antibodies on the surface of mast cells, triggering a response i.e. the degranulation of mast cells, releasing histamines which causes the constriction of blood vessels etc. and your typical allergic response ensues.
Yeah, you need to be able to distinguish between the different types of pathogens, their basic structure and their modes of infection, very briefly.

There's a slight difference, and what you've said pretty much sums it up.

re: viral infections, you only need to know that viruses infect by attaching to a host cell and injecting its viral nucleic acid, thereby overriding the host cell's own DNA and in effect, taking control of the cell's inner-machinery.

Thanks for that grannysmith

Also is it true that bacterias are susceptible to viral attacks? Is the process called bacteriophage, or is the virus called bacteriophage? And is it only viruses that can invade bacteria cells? Thanks!

[grannysmith]

Yah bacteria are susceptible to infections by special viruses called bacteriophages. They may be susceptible to other things besides bacteriophages, but not that I know of - and definitely not in the context of VCE Bio.

[vaish_vj]

In response to a memory cells job, why is it wrong to say a more "faster and stronger" response? also what is the correct answer? 

[grannysmith]

I wouldn't say it's incorrect, as the presence of memory cells does indeed produce a faster and greater response (through the production of a faster and greater amount of antibodies, if we're talking about B cells). However, perhaps the answer they are looking for is the 'actual' function of a memory cell which is to retain immunological memory of a specific antigen.