VCE Biology Question Thread

[vox nihili]

Click on the blue link on top of that post and it will redirect you to the question I posted, it was about meiosis and chromosomes, relating to the question I just recently posted about why meiosis can occur with the absence of chromosomes (the question I attached in the link says that meiosis cannot occur)

But yeah I get the gel electrophoresis one, cheers xD

Hmmm, it could be that there are mechanisms built into meiosis that terminate meiosis if each chromosome can't find a homologue. I daresay that's what's occurring here. I myself didn't mention that because I would have thought that were a bit beyond VCE.
Safe to assume that meiosis won't occur if one is missing a chromosome

[Biology24123]

For attached questions:

1. This is exactly what I wrote the paper, would I get the 3/3 marks or not, if not, please tell me what I need to change? Cheers

The poison Ivy toxin would have entered Paul's interior and must have been engulfed by macrophages, these macrophages will degrade and present fragments on their MHC Class II markers to activate specific Helper T cells. The Helper T cells will then activate specific B cells that also possess the toxin on their MHC II markers and are activated to proliferate into plasma and memory B cells. The plasma B cells will secrete specific IgE antibodies that will bind to mast cell membranes, when the toxin binds to these IgE antibodies, they stimulate the mast cells to degranulate and release histamine, which causes vasodilation of the blood vessels and increases permeability of capillary walls to increase the blood flow to the site of infection.

2.

For the second attachment, I did not talk about the speed of the propagation of the action potential at all.. I only said that in the given info, the hormone travels along the axon, whereas in the typical transport, the action potential travels along the axon. I also said that in the give example, the hormone is released to the blood vessels whereas in the typical neurone, the neurotransmitters are released in the synaptic gap to diffuse through to the post synaptic membrane.

What do you think? Would this get marks on the exam, because the assessors report only spoke about relative speeds of the thing, but the question specifically said 'transport'?

Many thanks in advance

T helper cells also proliferate.

Also, I think you use too many words in your answers and that might be wasting time during the exam.

[Biology24123]

How would you answer this. It's worth 6 marks on Insight 2011

[vox nihili]

How would you answer this. It's worth 6 marks on Insight 2011

Gonna leave this one and let everyone have a crack. A good question for discussion, if somewhat beyond the VCE course.

[StupidProdigy]

Can someone explain this please? I went for option C but it's A. I always get confused about what happens with homozygous or heterozygous alleles in gel electrophoresis, one is a single fragment and the other is two fragments of something yeah? Any tips for remembering it haha? Thanks guys

[cosine]

Can someone explain this please? I went for option C but it's A. I always get confused about what happens with homozygous or heterozygous alleles in gel electrophoresis, one is a single fragment and the other is two fragments of something yeah? Any tips for remembering it haha? Thanks guys

Because the person is heterozygous, then they have both alleles. So clearly one chromosome 1 has no cutting sites, that is one allele, and the other chromosome has a cutting site, so it is another allele, hence heterozygous. So:

If we use the same restriction enzyme for chromosome 1 on the heterozygous person, they will produce 2 fragments of DNA because the restriction enzyme recognises the specific DNA sequence present in the allele, and cut it, leaving two fragments of sizes 75kb and 125kb. The other chromosome will not have a recognition site, so the allele remains intact and no separation exists, so we have three total fragments of DNA, two from the first chromosome and one from the other, so you can rule out B and C. Now the two fragments cut by the restriction enzyme are 75kb and 125 kb, so look on the options for fragments of same size on the gel, leaving only A as the answer.

Hope that cleared it up for you

[cosine]

For attached questions:

1. This is exactly what I wrote the paper, would I get the 3/3 marks or not, if not, please tell me what I need to change? Cheers

The poison Ivy toxin would have entered Paul's interior and must have been engulfed by macrophages, these macrophages will degrade and present fragments on their MHC Class II markers to activate specific Helper T cells. The Helper T cells will then activate specific B cells that also possess the toxin on their MHC II markers and are activated to proliferate into plasma and memory B cells. The plasma B cells will secrete specific IgE antibodies that will bind to mast cell membranes, when the toxin binds to these IgE antibodies, they stimulate the mast cells to degranulate and release histamine, which causes vasodilation of the blood vessels and increases permeability of capillary walls to increase the blood flow to the site of infection.

2.

For the second attachment, I did not talk about the speed of the propagation of the action potential at all.. I only said that in the given info, the hormone travels along the axon, whereas in the typical transport, the action potential travels along the axon. I also said that in the give example, the hormone is released to the blood vessels whereas in the typical neurone, the neurotransmitters are released in the synaptic gap to diffuse through to the post synaptic membrane.

What do you think? Would this get marks on the exam, because the assessors report only spoke about relative speeds of the thing, but the question specifically said 'transport'?

Many thanks in advance

Can someone help please, thanks though Biology24, have any suggestions about how to keep it concise? Also, could anyone confirm what I said about both questions would gain full marks or not? Just trying to perfect my answers guys, hopefully someone can help out

[Sine]

With hominin evolution do we need to know the specific of each species or do we just need more general changes, such as smaller more uniform teeth, larger cranial capacity, reduced brow ridge, more parabolic dental arch, and other such as cultural/technological evolution.

Or do we need to know stuff like Homo habilis was the first to eat meat.

[heids]

With hominin evolution do we need to know the specific of each species or do we just need more general changes, such as smaller more uniform teeth, larger cranial capacity, reduced brow ridge, more parabolic dental arch, and other such as cultural/technological evolution.

Or do we need to know stuff like Homo habilis was the first to eat meat.

Yeah, general overall structural, cultural and technological trends, and then I'd know a general order of species, but not to link any one development or change to.

For attached questions:

1. This is exactly what I wrote the paper, would I get the 3/3 marks or not, if not, please tell me what I need to change? Cheers

The poison Ivy toxin would have entered Paul's interior and must have been engulfed by macrophages, these macrophages will degrade and present fragments on their MHC Class II markers to activate specific Helper T cells. The Helper T cells will then activate specific B cells that also possess the toxin on their MHC II markers and are activated to proliferate into plasma and memory B cells. The plasma B cells will secrete specific IgE antibodies that will bind to mast cell membranes, when the toxin binds to these IgE antibodies, they stimulate the mast cells to degranulate and release histamine, which causes vasodilation of the blood vessels and increases permeability of capillary walls to increase the blood flow to the site of infection.

Look at their suggested answer for an indication of what they want.  My guess is that they just wanted something like:
- B cells proliferate and produce IgE antibodies
- antibodies bind to mast cells
- on second exposure (note, you didn't mention this; it's important in allergic response), toxin binds to antibodies and stimulates mast cells... (then all you said)

Rethink: is this even a second exposure question?  I can't remember the question.

In other words, the whole thing about macrophages and T cells is not what they're looking for in an allergy question.  Overall, your writing was concise enough (tiny points like 'into Paul's interior'), but just too many details they don't need (you honestly don't need to know much for VCE Bio).

[Sine]

Yeah, general overall structural, cultural and technological trends, and then I'd know a general order of species, but not to link any one development or change to.

Thanks, so just for confirmation, Do we need to know about the genera Australopithecus and Homo and not Paranthropus and Ardipithecus?

[heids]

Thanks, so just for confirmation, Do we need to know about the genera Australopithecus and Homo and not Paranthropus and Ardipithecus?

I'd recommend knowing they exist, but there's never been a question on them (honest truth: had never heard of them till a couple of months ago).
you know the only thing I even do in this thread is tell people 'no don't learn that'

[Biology24123]

Yeah, general overall structural, cultural and technological trends, and then I'd know a general order of species, but not to link any one development or change to.
Look at their suggested answer for an indication of what they want.  My guess is that they just wanted something like:
- B cells proliferate and produce IgE antibodies
- antibodies bind to mast cells
- on second exposure (note, you didn't mention this; it's important in allergic response), toxin binds to antibodies and stimulates mast cells... (then all you said)

Rethink: is this even a second exposure question?  I can't remember the question.

In other words, the whole thing about macrophages and T cells is not what they're looking for in an allergy question.  Overall, your writing was concise enough (tiny points like 'into Paul's interior'), but just too many details they don't need (you honestly don't need to know much for VCE Bio).

So are T helper cells and macrophages involved in the allergic response. I would assume so?

[cosine]

Um so apparently the answer is C and apparently MHC I markers present antigens to B cells too?

[cosine]

The attached question asks for two advantages of having these memory B cells when the student receives their immunisation in Year 10, the answer said that there will be a more rapid production of antibodies when the students get immunised again, but how is that an advantage? Would this be more correct: "Because there already exists specific memory B cells for the bacterial antigen, reinvasion means a higher rate of proliferation leading to a rapid increase of memory B cells that will provide the student long-term immunity"

I don't see why having antibody production during an immunisation would be an advantage, because don't antibodies only stay in blood plasma for a couple of days? Thanks

[cosine]

1. Does stomach acid affect viruses?

2. For the attached question, where does it say that the polypeptides are subjected to being broken down by enzymes? Am I missing something or?