VCE Biology Question Thread

[simrat99]

Hi, can transcription occur without RNA polymerase? Thanks (:

[Quantum44]

Hi, can transcription occur without RNA polymerase? Thanks (:

RNA polymerase is the only enzyme that can catalyse transcription so I don't see how transcription could occur without it.

[ardria]

1. Is this a good definition for an antigen?
"Proteins on the surface of cell membranes that act as recognition sites for the immune system".

2. Are MHC markers antigens by definition? If not, what are the similarities and differences?
Nature of Bio seems to call them antigens, but I had thought they were proteins that bound to foreign antigens to present them to T cells.

Thanks in advance

[Quantum44]

1. Is this a good definition for an antigen?
"Proteins on the surface of cell membranes that act as recognition sites for the immune system".

2. Are MHC markers antigens by definition? If not, what are the similarities and differences?
Nature of Bio seems to call them antigens, but I had thought they were proteins that bound to foreign antigens to present them to T cells.

Thanks in advance

I think you are being a little too specific with your definition of an antigen, as they can also be made out of carbohydrates. Obviously the main aspect is that foreign antigens stimulate an immune response which involves the production of antibodies.

Well MHC markers are also known as HLA markers so they are antigens by definition. You could call MHC markers self-antigens.

[TFAnime123]

Can someone check if my answer is appropriate?
It was the first question on my Immunity SAC, worth 1 mark, but I think I pretty much would lose a mark already...

Describe the difference between natural and artificial immunity?
- Natural immunity: The production and receiving of antibodies through natural means, such as through the mother to the foetus and responding to an antigen.
- Artificial immunity: The production and receiving of antibodies via an external source, such as by a vaccination or injection.

[TheAspiringDoc]

Can someone check if my answer is appropriate?
It was the first question on my Immunity SAC, worth 1 mark, but I think I pretty much would lose a mark already...

Describe the difference between natural and artificial immunity?
- Natural immunity: The production and receiving of antibodies through natural means, such as through the mother to the foetus and responding to an antigen.
- Artificial immunity: The production and receiving of antibodies via an external source, such as by a vaccination or injection.

I think "responding to an antigen" as a bit vague an example of natural immunity as you also respond to antigens in vaccines.

[ardria]

Could only the cell-mediated immune response occur? Or are the only two possibilities:
- Humoral only
- Humoral then cell-mediated

[vox nihili]

Could only the cell-mediated immune response occur? Or are the only two possibilities:
- Humoral only
- Humoral then cell-mediated

They all work together.

[ardria]

They all work together.

Just want to be sure - they must occur together, and neither of them can occur independently?

[vox nihili]

Just want to be sure - they must occur together, and neither of them can occur independently?

It's pretty complicated and I'm weary of over-complicating things, simply because it's well beyond VCE. BUT, they can work independently, but typically don't. The way we divide the immune system into innate, adaptive and then into the different components thereof is for our benefit, not really because the immune system has deliberately organised itself that way.

[TheAspiringDoc]

It's pretty complicated and I'm weary of over-complicating things, simply because it's well beyond VCE. BUT, they can work independently, but typically don't. The way we divide the immune system into innate, adaptive and then into the different components thereof is for our benefit, not really because the immune system has deliberately organised itself that way.

Do viral infections only stimulate the cell mediated response though?

[pmmenotes]

Can someone explain the third line of defence for me? (immunity)

[Calebark]

Can someone explain the third line of defence for me? (immunity)

That's quite lengthy to explain. Is there any particular part you are stuck on? Any specific questions?

Perhaps this summary will help.

[vox nihili]

Do viral infections only stimulate the cell mediated response though?

No. There are antibodies mediated against viruses too.

[pmmenotes]

What would you say for a question asking you how to stop a disease in some village (relating to herd immunity im assuming) and the answer being antibiotics i would of thought it would be vaccines can someone explain this to me.

Also has anyone had the immunolgy sac i have it tomorrow and im worried bc so much CONTENT  surely they cant test us on all of this