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January 18, 2020, 10:56:56 am

Author Topic: VCE Biology Question Thread  (Read 1488331 times)  Share 

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Erutepa

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Re: VCE Biology Question Thread
« Reply #11865 on: August 17, 2019, 07:19:30 am »
+4
Just to clarify, can a frameshift mutation be a missense or nonsense mutation as well?
My understanding is that missense and nonsense mutations refer to a point mutation where only one amino acid is changed whereas a framshift involves many amino acids downstream of the point mutation being changed.
So I don't think framshift mutations can be nonsense or missense.
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Chocolatemilkshake

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Re: VCE Biology Question Thread
« Reply #11866 on: August 17, 2019, 09:12:04 am »
0
My understanding is that missense and nonsense mutations refer to a point mutation where only one amino acid is changed whereas a framshift involves many amino acids downstream of the point mutation being changed.
So I don't think framshift mutations can be nonsense or missense.

Thank you! Also wondering...

1. What's the difference between a block insertion and a block translocation?
2. Is a block translocation the swapping parts of two chromosomes or just the moving of ONE part? (different resources say different things)
3. Can a translocation only occur in non-homologous chromosomes?
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Erutepa

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Re: VCE Biology Question Thread
« Reply #11867 on: August 17, 2019, 04:27:50 pm »
+4
Thank you! Also wondering...

1. What's the difference between a block insertion and a block translocation?
2. Is a block translocation the swapping parts of two chromosomes or just the moving of ONE part? (different resources say different things)
3. Can a translocation only occur in non-homologous chromosomes?
Block insertion in when a segment of one chromosome is inserted into another whereas a translocation is where two chromosome segments switch places. So insertion is one segment moving somewhere else and translocation is the swapping of two segments.
Im not sure if they only happen between non-homologous chromosomes, however all the examples I've found seem only show translocation occurring between non-homologous chromosomes. Hopefully someone more knowledged may be able to help, but I don't think this knowledge is neccasary for VCE.
Hopefully this clears things up.
« Last Edit: August 17, 2019, 04:31:32 pm by Erutepa »
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Evolio

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Re: VCE Biology Question Thread
« Reply #11868 on: August 18, 2019, 10:43:03 am »
0
Hi guys!
How are you doing?

Since mitochondrial DNA mutates at a faster rate than nuclear DNA, I was wondering what the benefit of this was relating to this fact?
Also, why is mitochondrial DNA used when nuclear DNA can just be used?
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darkz

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Re: VCE Biology Question Thread
« Reply #11869 on: August 18, 2019, 11:23:45 am »
+3
Hi guys!
How are you doing?
Since mitochondrial DNA mutates at a faster rate than nuclear DNA, I was wondering what the benefit of this was relating to this fact?
Also, why is mitochondrial DNA used when nuclear DNA can just be used?

Well because it mutates faster, therefore, it would be easier to make comparisons with other organisms - i.e. more differences as time progresses. (e.g. Would prove quite useful in determining relatedness for recently diverged species, since the differences would be quite prominent, unlike nuclear DNA, which would have less differences, making it harder to conclude anything.)

mtDNA is generally preferred compared to nuclear DNA because of the following features:
  • Only inherited from mother
  • Does not undergo recombination
  • Not repaired by enzymes
Therefore, it can be highly effective in determining familial lineages. Also, since mtDNA doesn't undergo repair, therefore you can more accurately apply the molecular clock theory, compared with nuclear DNA which does undergo repair.
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Evolio

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Re: VCE Biology Question Thread
« Reply #11870 on: August 18, 2019, 11:30:33 am »
0
Okay, thank you!
I looked at the notes you linked in your signature regarding the molecular clock principle.
With this principle, do you assume that there were 0 mutations at the time of divergence so that when you find the total number of mutations with the known mutation rate, you can figure out the time since they last diverged? Does this mean that there would be the same number of mutations having had occurred in both species?

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darkz

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Re: VCE Biology Question Thread
« Reply #11871 on: August 18, 2019, 11:56:05 am »
+4
Okay, thank you!
I looked at the notes you linked in your signature regarding the molecular clock principle.
With this principle, do you assume that there were 0 mutations at the time of divergence so that when you find the total number of mutations with the known mutation rate, you can figure out the time since they last diverged? Does this mean that there would be the same number of mutations having had occurred in both species?

Yep, you'd assume that there are no differences at the time of divergence. Maybe in the ideal world, there would be the same number of mutations having occurred, but since you can have things like A -> T -> A, which you wouldn't be able to detect, it is all very theoretical.
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Chocolatemilkshake

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Re: VCE Biology Question Thread
« Reply #11872 on: August 18, 2019, 11:57:11 am »
0
Are a selecting agent and a selection pressure the same thing or are they different?
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darkz

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Re: VCE Biology Question Thread
« Reply #11873 on: August 18, 2019, 12:09:52 pm »
+2
Are a selecting agent and a selection pressure the same thing or are they different?

Yes, they can be used interchangeably.
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Evolio

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Re: VCE Biology Question Thread
« Reply #11874 on: August 24, 2019, 01:26:52 pm »
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Yep, you'd assume that there are no differences at the time of divergence. Maybe in the ideal world, there would be the same number of mutations having occurred, but since you can have things like A -> T -> A, which you wouldn't be able to detect, it is all very theoretical.
Thanks, darkz!

Hi guys!
I have a few questions I want to clarify.

1. Does allopatric speciation occur at the same time? Like, there was a question on checkpoints asking whether allopatric speciation occurred based on analysing a phylogenetic tree. I said no because the different bat species speciated at different times and not the same time, thus it wouldn't be allopatric speciation.

2. When asked to define gene pool, I said the total collection of genes present in a population. Checkpoints said that it is wrong to say this. Is it because it sounds like I'm talking about the number of genes and it doesn't focus on the variations of the gene(allele)?

3. Also, mitochondria DNA, is single stranded and circular right? Because it was thought to once be a prokaryote?
Thanks in advance!
 ;D
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #11875 on: August 24, 2019, 02:08:03 pm »
+2
Thanks, darkz!

Hi guys!
I have a few questions I want to clarify.

1. Does allopatric speciation occur at the same time? Like, there was a question on checkpoints asking whether allopatric speciation occurred based on analysing a phylogenetic tree. I said no because the different bat species speciated at different times and not the same time, thus it wouldn't be allopatric speciation.

2. When asked to define gene pool, I said the total collection of genes present in a population. Checkpoints said that it is wrong to say this. Is it because it sounds like I'm talking about the number of genes and it doesn't focus on the variations of the gene(allele)?

3. Also, mitochondria DNA, is single stranded and circular right? Because it was thought to once be a prokaryote?
Thanks in advance!
 ;D
1. Depends how many groups you're talking about. If you've only got two groups (which is the most common scenario) then they must speciate at the same time because when group A can no longer interbreed with group B, then group B also can't interbreed with group A, therefore they're different species.

If you're talking about more than two groups then they can speciate at different times - for example if three groups of the same species are separated onto three different islands, they each become their own species when they can no longer interbreed. So if group A can no longer interbreed with either group B or group C then it's a separate species, but if group B and group C can still interbreed then they're still the same species, and it might take longer for them to speciate. Generally the evidence you need to know that it's allopatric speciation is just to know that the speciation occurred due to geographical separation.

2. Say the total variety of genes instead (also don't worry about having perfect definitions for the exam, you won't need them).

3.It's double stranded & circular
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Comet striker

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Re: VCE Biology Question Thread
« Reply #11876 on: August 25, 2019, 12:27:19 pm »
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Hey there,
During bacterial transformation, why are non recombinant plasmids added along with recombinant plasmids? Why not only add recombinant plasmids?
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Erutepa

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Re: VCE Biology Question Thread
« Reply #11877 on: August 25, 2019, 01:13:38 pm »
+3
Hey there,
During bacterial transformation, why are non recombinant plasmids added along with recombinant plasmids? Why not only add recombinant plasmids?
they aren't intentionally added as such, but rather they are added since the recombination process isn't perfect. Some plasmids don't successfully take up the desired gene in the recombination process and thus remain boring old plasmids. Thus, after bacterial transformation, some bacteria will possess just boring old plasmids and in order to obtain only bacteria with the recombinant plasmids, some sort of selection process will be preformed.
I suspect the reason for this is that it is easier to select for the bacteria with the recombinant plasmid rather than selecting for the recombinant plasmid itself and then performing bacterial transformation with the desired plasmids only.
Hopefully that makes sense. :)
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Chocolatemilkshake

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Re: VCE Biology Question Thread
« Reply #11878 on: August 28, 2019, 07:33:15 pm »
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Hi all,

Is it necessary to know the different types of phylogenic trees and what a cladogram is? Or do you just need to be able to formulate a general phylogenic tree/interpret them?

Thanks  :)
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Erutepa

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Re: VCE Biology Question Thread
« Reply #11879 on: August 28, 2019, 08:34:15 pm »
+2
Hi all,

Is it necessary to know the different types of phylogenic trees and what a cladogram is? Or do you just need to be able to formulate a general phylogenic tree/interpret them?

Thanks  :)
is this for units 1/2 or units 3/4 biology?

for units 3/4 you do not need to know about phylogenetic trees or cladograms. That was taken out of the study design as of 2017.

For units 1/2 you do need to know about phylogenetic trees, but I'm not sure about the specifics you are asking (I don't remember much 1/2 bio)

EDIT: please disregard my incorrect statement above.
 I unfortunately confused phylogenetic trees with pedigree charts and just realised now how foolish i have been. Pedigree charts are not needed, but you do need to know how to interpret phylogenetic trees in relation to the relatedness of different species just as Phoenixx Fire has said below.
« Last Edit: August 29, 2019, 10:44:31 am by Erutepa »
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