VCE Biology Question Thread

[FrankieDens]

Hey guys,

Which pathogens does each adaptive immune response attack? What I mean is that does the humoral response attack viral pathogens or bacterial pathogens? Does the cell-mediated response only attach infected cells?

Thanks! 
Hello!

Can someone briefly outline the theory of the bacterial origin of chloroplasts and mitochondria?


Thank you! 

Mod edit (PF): Merged posts. Please edit your post if you want to add something rather than posting twice in quick succession.

[Comet striker]

Hey guys,

Which pathogens does each adaptive immune response attack? What I mean is that does the humoral response attack viral pathogens or bacterial pathogens? Does the cell-mediated response only attach infected cells?

Thanks! 

I believe humoral response can attack any viral pathogen and bacterial pathogens in the bloodstream while cell mediated response can kill only virally infected cells or cancer cells. thats what I think is correct might be completely wrong though.

Hello!

Can someone briefly outline the theory of the bacterial origin of chloroplasts and mitochondria?


Thank you! 

Eukaryote engulfed cyanobacteria and rather than break it down, they formed a symbiotic relationship. Eukaryote provided protection and nutrients while prokaryote broke those nutrients down for energy. I dont think VCAA expects you to know this detail though as most will probably ask what features make the endosymbiosis theory correct. Eg: Mitonchondria and chloroplast having their own circular DNA.

[Erutepa]

From the ATAR notes exam, 3e:
By what mechanisms may protein synthesis be increased by this pathway(signalling molecule causes changes in gene expression)?
Answer:

Spoiler

Increasing transcription and/or translation. The production of mRNA can be increased by upregulating
the production or activity of relevant transcription factors or upregulating the translation of each
mRNA i.e. increase the amount of times each strand of mRNA is translated.

I wrote along the lines of increasing transcription by activating more RNA polymerase and increasing the rate of translation by producing more tRNA molecules. Would I get any marks for this?

The answer key itself says you can get 2 marks by stating an increase in both transcription and translation, so on that basis you would get both marks. Your examples also demonstrate knowledge of the necessary factors in the expression of genes as well.

[IThinkIFailed]

Hey, this may seem like a strange question, but
Do bacteria have rights?
If bacteria don’t have rights, is this an ethical implication for gene cloning, as we don’t have to worry about infringing upon organism’s rights?

Also, would an ethical implication of Genetic screening and GMOs be that manipulating the gene pool can be seen as unethical?

[caqiu]

Hey,
Could someone explain the multi-regional and out of Africa theories to me?
There a question on the 2015 vcaa exam that I'm a bit confused about.
The answer states:
Out of Africa
Humans first evolved in Africa where there were no Neanderthal populations as there is no
Neanderthal DNA in populations in Africa, and populations of humans moved out Africa and
encountered other Homo species. This is supported by the presence of Homo neanderthalensis
DNA in all modern humans except African populations.

However I wrote that it supports the Multi-regional theory. Because doesn't the multiregional theory hypothesise h.sapiens migrated out of Africa and spread across the world, evolved simultaneously and remained in genetic contact with the other hominin populations.

[PhoenixxFire]

Hey, this may seem like a strange question, but
Do bacteria have rights?
If bacteria don’t have rights, is this an ethical implication for gene cloning, as we don’t have to worry about infringing upon organism’s rights?

They don't. You could argue that it's an ethical implication with the idea that using bacteria in experiments impacts on another living organism, i'd be careful how you word it though - there is no violation of rights because they don't have rights.

Also, would an ethical implication of Genetic screening and GMOs be that manipulating the gene pool can be seen as unethical?

Yep. This is normally approached from a religious perspective. ie. "playing god"

Hey,
Could someone explain the multi-regional and out of Africa theories to me?
There a question on the 2015 vcaa exam that I'm a bit confused about.
The answer states:
Out of Africa
Humans first evolved in Africa where there were no Neanderthal populations as there is no
Neanderthal DNA in populations in Africa, and populations of humans moved out Africa and
encountered other Homo species. This is supported by the presence of Homo neanderthalensis
DNA in all modern humans except African populations.

However I wrote that it supports the Multi-regional theory. Because doesn't the multiregional theory hypothesise h.sapiens migrated out of Africa and spread across the world, evolved simultaneously and remained in genetic contact with the other hominin populations.

It looks like you've got the right idea about both hypothesis. However, this evidence doesn't support the multi regional hypothesis because the mutli regional hypothesis presumes that there's gene flow between all populations and that they're all the same species (it says that neanderthals are a subspecies of the same human species) which doesn't explain how neanderthal dna is in every population except african dna - if the multiregional hypothesis were correct then it should be found everywhere.

[Livcur16]

Hey guys,
What is expected to be known about this part of the study design:
"the human fossil record as an example of a classification scheme that is open to interpretations that are
contested, refined or replaced when new evidence challenges them or when a new model has greater
explanatory power, including whether Homo sapiens and Homo neanderthalensis interbred and the placement
of the Denisovans into the Homo evolutionary tree. "

In the 2016 VCAA question 3c, the report says phagocytosis of cell debris will not be accepted, why is this?

When are B cells and T cells referred to as naive; before they come into contact with the pathogen, or before they are activated by Helper T cells (and after they have bound to a pathogen/ recognised an infected cell that are specific to their receptors)?

Also, does the specific B cell/Tc need to come into direct contact with the specific Th cell, or can the cytokines move through the a system to activate the B cell / Tc cell?
Thankyou

[PhoenixxFire]

Hey guys,
What is expected to be known about this part of the study design:
"the human fossil record as an example of a classification scheme that is open to interpretations that are
contested, refined or replaced when new evidence challenges them or when a new model has greater
explanatory power, including whether Homo sapiens and Homo neanderthalensis interbred and the placement
of the Denisovans into the Homo evolutionary tree. "

It's a bit open to interpretation, but based on past exams I'd say it includes evolutionary theories (e.g. out of africa/multi regional hypothesis), knowing that neanderthal dna is in all homo sapien populations except african, and that there's genetic evidence that denisovans interbred with both neanderthals and humans.

In the 2016 VCAA question 3c, the report says phagocytosis of cell debris will not be accepted, why is this?

It's not considered to be part of apoptosis.

When are B cells and T cells referred to as naive; before they come into contact with the pathogen, or before they are activated by Helper T cells (and after they have bound to a pathogen/ recognised an infected cell that are specific to their receptors)?

Before they come into contact with an antigen they can bind to (note that anitgen=/= pathogen). After that they're selected/activated.

Also, does the specific B cell/Tc need to come into direct contact with the specific Th cell, or can the cytokines move through the a system to activate the B cell / Tc cell?
Thankyou

The Tc cell does not come into contact, the B cell does.

[caqiu]

Do you have to write everything in the box? If its out of the box is it not scanned

[PhoenixxFire]

Do you have to write everything in the box? If its out of the box is it not scanned

You don't have to write on the lines (although that makes it easier to read and is a good indication of how much to write) - you can write below the lines or to the side, but don't write outside the box around where the page margins are - this'll be the part where it says "DO NOT WRITE HERE" outside the line. It *might* still get scanned, but that's the part of the page that could get lost during scanning so there's no guarantee that your examiners will be able to see anything that you write there. Don't risk it.

[caqiu]

You don't have to write on the lines (although that makes it easier to read and is a good indication of how much to write) - you can write below the lines or to the side, but don't write outside the box around where the page margins are - this'll be the part where it says "DO NOT WRITE HERE" outside the line. It *might* still get scanned, but that's the part of the page that could get lost during scanning so there's no guarantee that your examiners will be able to see anything that you write there. Don't risk it.

Thanks!
If I put a * and wrote more does it have to be on the same page as the question e.g. page that contain context and I write a)* (since is it that different examiners mark different pages?)
What do I do if there is no free space left of me to write?

[PhoenixxFire]

Thanks!
If I put a * and wrote more does it have to be on the same page as the question e.g. page that contain context and I write a)* (since is it that different examiners mark different pages?)
What do I do if there is no free space left of me to write?

I would avoid doing it wherever possible. If you absolutely have to write more then write it as close to the question as you can (e.g writing it along the side of the lines). I have heard that examiners mark the same question many times rather than marking whole exams but I don't know how true it is. AFAIK there isn't any provision in bio for extra writing space, so you won't really have the option of writing anywhere else. You'll probably just have to have a rough idea of what to write before you start writing and write really small if you think it's going to take more space than you have. The number of lines should be a good indication of how much to write anyway - If you've been writing far too much in past exams you've attempted so far, then use the next couple of days to go back through those exams and put a line through what you didn't need to include so you can get a better idea of what sort of information you can leave out of your answers on the exam.

[K.Niva]

Hey everyone!
 
I was doing the NEAP 2019 practice exam and was wondering whether we need to know about reverse transcriptase as it was mentioned in majority of Question 3 in the short answer section?

Thank you! Good luck to everyone!

[PhoenixxFire]

Hey everyone!
 
I was doing the NEAP 2019 practice exam and was wondering whether we need to know about reverse transcriptase as it was mentioned in majority of Question 3 in the short answer section?

Thank you! Good luck to everyone!

Were you required to answer questions about what it is or was it just in the stem?
The only part of the study design that it could possibly come under would be "invading cellular and non-cellular pathogens as a source of non-self antigens" but I'd say it's a bit of a stretch for that to include knowing how rna viruses work. I really doubt you'd be expected to know anything about it.

[Comet striker]

Hey there doing the NHT VCAA 2017 got a few questions:
For question 4b(ii) [context provided in attachment]:
It asks for two controls for the experiment:
would pH be a control for the experiment? the answers dont state ph as a solution so if not why wouldnt ph be a solution.

From question 7c:
[PCR is the context]
What is the function of the DNA primers in the mixture?:
I wrote: DNA primers anneal to specific gene of interest using complementary bases and allow Taq polymerase to bind to the DNA strand.
Would this a good answer?

And finally for question 10 c:
Identify two beetle species that would have the least number of differences in their DNA sequences. Explain your answer.
The answer says Species W and X as a "possible answer" Are there other species that can be a possible answer?
Thnx for the help

Man its been a while since I've used BB code