VCE Biology Question Thread

[Erutepa]

1) How does the body differentiate between self and non-self non-cellular objects (i.e proteins) seeing as proteins lack MHC1 markers, I can't see how they would be distinguished.
2) Are cytotoxic T cells stimulated to divide the same way that B cells are?

1. free proteins can still be engulfed by APC which regularly just consume proteins from their surroundings. As such, they can be presented to elicit an adaptive immune response just like any other antigen would. If this is a self-antigen, no immune response would result as the body's tolerance systems would mean that all B and T cells that are self-reactive are killed via apoptosis.
2. Their activation is a bit different, but for our purposes, I think you can say yes.

1) Does founder effect result in speciation always?

2) Is competitive inhibition always go with reversible inhibition and non-competitive irreversible?

3) Describe a technique that could be used to compare the sequence of the mitochondrial DNA to confirm the arrangement of the phylogenetic tree?
Would DNA sequencing be an option? The more similar the sequence of nucleotides, the less time since divergence from common ancestor thus the more closely related they are.  The only answer given was DNA hybridization

1. Given enough time and assuming no gene flow occurs between the founder population and the parent population then speciation would likely occur. I doubt that you will be asked this question though.
2. I am not sure about this.
3. For these questions I would always write DNA hybridization as I am specifically mentioned as a tool in the study design, however, sequencing would be correct.

[galaxy21]

I don’t get the solutions. Could someone help me out please

Basically, the scientists did not include the non-coding regions, as they do not code for proteins, so there is really no point using these regions to compare the cytochrome C protein. It will only potentially show extra mutations that do not have an effect on the protein (the phenotype) itself.

[PhoenixxFire]

2) Are cytotoxic T cells stimulated to divide the same way that B cells are?

2. What do you mean? Like with the Th cell? The cytokines from Th cells help stimulate Tc cells, but I'm not sure exactly how that happens.

1) Does founder effect result in speciation always?

2) Is competitive inhibition always go with reversible inhibition, and non-competitive irreversible?

3) Describe a technique that could be used to compare the sequence of the mitochondrial DNA to confirm the arrangement of the phylogenetic tree?
Would DNA sequencing be an option? The more similar the sequence of nucleotides, the less time since divergence from common ancestor thus the more closely related they are.  The only answer given was DNA hybridisation

1. Not necessarily. The founding population could still be capable of interbreeding with the original population. It just results in lower genetic diversity.

2. For VCE, yes.

3. Yes but it wouldn't really be done because it's harder. Just stick with hybridisation if you get a question on that (not sure if VCAA would mark both correct).

[Erutepa]

Hey...a few more questions...
1. Does carbon-14 dating have a minimum age of the fossil? My teacher has said 12 years, but I haven't seen this anywhere else.
2. Are glycolipids and glycoproteins used as receptors?
3. After how many years, roughly, is a similarity in traits not considered to have been from a common ancestor, but by convergent evolution?
4. With the final heating stage of DNA hybridisation, is it the point that the DNA strand completely separate, or when 50% of the bonds are broken that the temperature is noted to use to determine relatedness between species?

1. There would be a minimum age a fossil needed to be for carbon dating to be reliable, however, I am not sure what it is. You wouldn't need to know about it though.
2. glycoproteins are receptors, but not glycolipids
3. Convergent evolution is mainly indicated by shared traits of different evolutionary origins indicated by a different structure/form or mechanism. For example birds and bee's show convergent evolution in their possession of flight and wings, however, the structure of the wings are very different which indicates that evolved separately.
4. I believe that it is the temperature needed to completely separate both strands, although I may be mistaken.

[yebavin]

i have one question, what is continuous variation and is it on the study design?
Thanks

[Robot10]

Did Australopithecus have prehensile toes? Are prehensile toes  the same as opposable thumbs on toes?

[PhoenixxFire]

4. With the final heating stage of DNA hybridisation, is it the point that the DNA strand completely separate, or when 50% of the bonds are broken that the temperature is noted to use to determine relatedness between species?

According to wikipedia it's half. Unless you get specifically asked about it I would just say something generic about it being when the DNA becomes single stranded though. Note: It's when half the DNA is single stranded, not when half the bonds are broken.

i have one question, what is continuous variation and is it on the study design?
Thanks

Not on the study design

[vox nihili]

Did Australopithecus have prehensile toes? Are prehensile toes  the same as opposable thumbs on toes?

Yes, but well and truly beyond the study design.

https://www.nature.com/news/ancient-human-ancestor-had-feet-like-an-ape-1.10342

[Erutepa]

i have one question, what is continuous variation and is it on the study design?
Thanks

Continuous variation refers to traits which exist in a population that exist as a continuous spectrum between two extremes. Height Is an example of this.
It is not on the study design

[Hiea]

Regarding the steps in signal transduction (reception, signal transduction, and cellular response): how would you label the steps in a pathway with a hydrophobic signalling molecule, assuming that reception doesn't lead to the release of second messngers? Would the formation of the ligand-receptor complex cover both reception and transduction?

[Erutepa]

Regarding the steps in signal transduction (reception, signal transduction, and cellular response): how would you label the steps in a pathway with a hydrophobic signalling molecule, assuming that reception doesn't lead to the release of second messngers? Would the formation of the ligand-receptor complex cover both reception and transduction?

The signal reception is still going to be the binding of the signal to the receptor. I would say the transduction of the signal is the action of the signal-receptor complex, which for us is its action as a transcription factor altering the transcription of a gene. This altered expression then will bring about a response.

[vox nihili]

Regarding the steps in signal transduction (reception, signal transduction, and cellular response): how would you label the steps in a pathway with a hydrophobic signalling molecule, assuming that reception doesn't lead to the release of second messngers? Would the formation of the ligand-receptor complex cover both reception and transduction?

It's probably not helpful to use that model for hydrophobic signalling, but yeah basically it would. You could say that activation of the gene kind of stands in place for transduction, for example. Transduction obviously doesn't happen in hydrophobic signalling. It shouldn't matter at the end of the day, if you're comfortable explaining how we get from ligand to response, how you put that shouldn't matter

[EllingtonFeint]

Do we actually need to know about the parallel evolution hypothesis?

[PhoenixxFire]

Do we actually need to know about the parallel evolution hypothesis?

Do you mean the multi-regional evolution theory that states the humans evolved through parallel evolution? There is nothing on the study design about knowing any evolutionary theory, and VCAA has stated that you don't need to know which species evolved from which, so I kind of doubt it. But everyone seems to be getting taught about it so I'm not sure (it could come under the human fossil record part of the study design, but I feel like VCAA would have at least mentioned evolutionary theories rather than just classification schemes)

[starby]

Few questions

Do we need to know which elements macromolecules are composed of?

Do we need to know the bonds in each protein structure?

Do we need to know the stimulus response model?

Thanks guys