VCE Biology Question Thread

[vox nihili]

How do the homologous chromosomes in meiosis 'know' to line up next to each other in metaphase I?
Mitosis and meiosis start off with the same amount/types etc of chromosomes but the align themselves in different ways depending on the purpose of the division so how does this actually occur?

Well beyond VCE.

Basically there are proteins produced in meiotic cells that make this happen, that just don't exist in mitotic cells.

[Hayley_turnham]

Well beyond VCE.

Basically there are proteins produced in meiotic cells that make this happen, that just don't exist in mitotic cells.

makes sense ahah thanks

[AhNeon]

I've been hearing conflicting stuff about this. Does transcription entail the whole process of the synthesis of mRNA from DNA, or is the modification of pre-mRNA not part of transcription
Also, do lipid-based hormones undergo the whole amplification thing that protein-based ones do? if so, how?
Are pure bred organisms just ones that are homozygous for whatever trait?
Thanks guys

[The Usual Student]

For VCE biology can the terms charged and polar be used interchangeably?

[FatimaEl]

I've been hearing conflicting stuff about this. Does transcription entail the whole process of the synthesis of mRNA from DNA, or is the modification of pre-mRNA not part of transcription
Also, do lipid-based hormones undergo the whole amplification thing that protein-based ones do? if so, how?
Are pure bred organisms just ones that are homozygous for whatever trait?
Thanks guys

- Transcription does not involve modification of pre-mRNA, as pre-mRNA modification is also known as post-transcriptional modification, the word transcription is simple referring to the formation of a pre-mRNA strand from a dna template
- Yes there is an amplification process for lipid based hormones, "Transduction for both lipid-based and protein-based signalling molecules involves a cascade of reactions that amplify the initial message," (this is directly from the vcaa frequently asked questions document), as for the how part of your question, i dont think we are required to know specifics of amplifications "Details of specific[...]cascade reactions are not required." (also from the vcaa document)
- And yes, pure bred organisms refer to being homozygous for a trait, having two of the exact same allele

hope that helped

[Angelx001]

I'd only give it one mark. You don't make any reference to the question in your answer. The question specifically asks you to talk about how the number of cases could increase—you needed to explain the link.

"A mutation in the mumps virus makes the virus resistant to the mumps vaccine. The resistant virus is thus able to infect people vaccinated against the virus, leading to an increase in the number of mumps cases".

Another option would be to talk about a drop in the vaccination rate, which I'm pretty sure is what's happened recently

Anyway tl;dr right thinking but need to be clearer

The answer is well beyond VCE, so you definitely don't need to know.

Simply though, it could actually line up with either one. Translocations like this are a big source of chromosomal abnormalities in foetuses.

Just for fun, and once again well beyond VCE, the Y chromosome actually lines up with the X...otherwise how do we ensure that each gamete only gets one X or one Y?

How would a drop in the vaccination rate increase the number of cases of mumps occurring?
Is it because there is no herd immunity?
Thank you

[Gogo14]

How would a drop in the vaccination rate increase the number of cases of mumps occurring?
Is it because there is no herd immunity?
Thank you

A decrease in vaccination rate means that less people have active immunity to mumps.
Therefore they more susceptible to contracting mumps. This is on an individual scale, on a population scale, however, herd immunity does become a significant issue.

Also, what releases complement proteins and what stimulates the release?

[vox nihili]

- Yes there is an amplification process for lipid based hormones, "Transduction for both lipid-based and protein-based signalling molecules involves a cascade of reactions that amplify the initial message," (this is directly from the vcaa frequently asked questions document), as for the how part of your question, i dont think we are required to know specifics of amplifications "Details of specific[...]cascade reactions are not required." (also from the vcaa document)

lel, VCAA lied (go with what VCAA says though!!!)

A decrease in vaccination rate means that less people have active immunity to mumps.
Therefore they more susceptible to contracting mumps. This is on an individual scale, on a population scale, however, herd immunity does become a significant issue.

Also, what releases complement proteins and what stimulates the release?

You don't need to know about complement to that level of detail (it basically just hangs around in the blood waiting to be activated by other cells of the immune system, such as B-cells and neutrophils...it's actually made in the liver)

Spot on about the vaccination rate. If there are fewer people vaccinated, more can get the disease. Herd immunity can become an issue, only if you drop below a certain level of vaccination in a community (*cough* Brunswick)

[plsbegentle]

do we need to know the types of hormones involved in plants? (ethylene, auxin etc)

[FatimaEl]

lel, VCAA lied (go with what VCAA says though!!!)

what do you mean by vcaa lied?

[vox nihili]

what do you mean by vcaa lied?

VCAA knowledge: lipid hormones undergo amplification, as do protein-based hormones

Truth: lipid hormones don't undergo amplification (it's a bit more complicated than this, but there's no point dissecting the details because it's all beyond VCE).

[FatimaEl]

VCAA knowledge: lipid hormones undergo amplification, as do protein-based hormones

Truth: lipid hormones don't undergo amplification (it's a bit more complicated than this, but there's no point dissecting the details because it's all beyond VCE).

oh okay i get you, and so we should just go with vcaa knowledge? also will a question even ask us that?

[vox nihili]

oh okay i get you, and so we should just go with vcaa knowledge? also will a question even ask us that?

Yes always go with VCAA knowledge, as they're the ones testing you (not me!). I couldn't say, I don't write the exams. It could?

[AhNeon]

From VCAA 2003.
 I get that it could be environmental affects (the correct answer), but as the stem of the question says 'genetically identical at a particular single gene locus', can it not also be polygenic inheritance and the variation be due to other genes at other gene loci. This also supports the fact that there are a wide variety of phenotypes

[Sine]

From VCAA 2003.
 I get that it could be environmental affects (the correct answer), but as the stem of the question says 'genetically identical at a particular single gene locus', can it not also be polygenic inheritance and the variation be due to other genes at other gene loci. This also supports the fact that there are a wide variety of phenotypes

The question kinda implies/explicitly states that it's for a single gene. Don't try to be too fancy, especially on short answer questions just give the most logical answer as more obscure answers which may be correct may not be interpreted in the way you intend.