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Author Topic: VCE Biology Question Thread  (Read 3570913 times)  Share 

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IThinkIFailed

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Re: VCE Biology Question Thread
« Reply #12075 on: October 15, 2019, 10:19:59 pm »
0
APC's do have both MHC1 and MHC2, however the only antigens presented on MHC1 are protein fragments synthesised by the cell - so antigens that are engulfed are only presented on MHC2, not MHC1.

APC's can present antigens on their MHC1 to Tc cells, the same way any other cell can, but this will kill the APC because it signals that the APC is infected. APC's can also present on MHC2 to activate T helper cells, which is why they're called APC's.

The cytokines released from Th cells when they come into contact with an activated B cell with the same antigen specificity are required for Tc cells to divide and differentiate, however VCAA considers Th and B cells as part of humoral immunity, and Tc cells as part of cell mediated immunity. So if you get a question on cell mediated immunity, it's okay to mention that the Tc cells are stimulated by cytokines released from activated Th cells, but you won't need to go into any sort of detail on it, save that for the humoral immunity questions.

In addition to what other said, make sure you specify that it's a membrane bound receptor. Also for 3. I'd also mention that the cascade of events leads to a cellular response.

this is what vcaa said about it

Thanks for the feedback on my DNA hybridisation and signal transduction process!

I modified my DNA hybridisation process a bit, can someone see if this is a bit better?

1: Source double stranded DNA from the cells of two different species, mixing them in a solution
2: Heat the double stranded DNA to 95 degrees Celsius, denaturing the DNA and causing them to disassociate into single strands
3: Cool the solution, allowing the single stranded samples from both species, to bond via hydrogen bonds between complementary bases.
4: Heat the sample of the two species, and measure how much temperature it took to denature the double stranded hybrid DNA, comparing it with the original melting temperature. The higher the temperature required, the higher the degree of complementary base pairing and thus the more related the species are.
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12076 on: October 16, 2019, 02:43:44 pm »
+4
Thanks for the feedback on my DNA hybridisation and signal transduction process!

I modified my DNA hybridisation process a bit, can someone see if this is a bit better?

1: Source double stranded DNA from the cells of two different species, mixing them in a solution
2: Heat the double stranded DNA to 95 degrees Celsius, denaturing the DNA and causing them to disassociate into single strands
3: Cool the solution, allowing the single stranded samples from both species, to bond via hydrogen bonds between complementary bases.
4: Heat the sample of the two species, and measure how much temperature it took to denature the double stranded hybrid DNA, comparing it with the original melting temperature. The higher the temperature required, the higher the degree of complementary base pairing and thus the more related the species are.
Yep, looks good. For point 3. though, say "measure the temperature at which it denatures" not "how much temperature it took to denature".
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Evolio

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Re: VCE Biology Question Thread
« Reply #12077 on: October 16, 2019, 07:11:21 pm »
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Thank you ssillyssnakes and Erutepa!  ;D It makes so much sense now! I really appreciate all your help.

I had more questions to ask from the 2009 Biology Exam 2.
 
4 a i Describe how this fossil could have formed. 1 mark
I wrote that the bird could have fallen into mud which would have hardened over time. Would this get me the mark? How do you know how much detail to put because the answer says 'rapidly buried by sediment' and hidden from scavengers with other points as well and it's only 1 mark.

4 b ii Explain how isolation can result in speciation
The answer said to include that there was different genetic variation in the two groups but I was wondering why? All the questions I've done with allopatric speciaion have never included that phrase, including VCAA ones.

From the same exam, I don't understand questions 7 b and e. I attempted it but I got it wrong and so I don't think I interpreted the questions properly? I'm not sure why VCAA's answer is correct and how they got that?



« Last Edit: October 16, 2019, 07:14:59 pm by Evolio »

alexthenerd

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Re: VCE Biology Question Thread
« Reply #12078 on: October 16, 2019, 07:30:32 pm »
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hey guys i just had a question from 2010 exam 1

question 23 multiple choice
i answered enzyme K but enzyme J is the answer. i was just wondering what makes enzyme J any more correct? they are both in an alkaline environment just with different optimum temperature ranges. from what i thought, washing machines washed clothes with hot water therefore this would make enzyme K more correct.

thanks in advance
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Evolio

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Re: VCE Biology Question Thread
« Reply #12079 on: October 16, 2019, 07:38:50 pm »
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I got this question wrong as well.
I thought about how J has a more wider temperature range and the temperature used to wash clothes can be colder or warmer, depending on the type of clothes you want to wash. So, since it has a wider temp range, that would be correct.
Does this make sense?


Erutepa

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Re: VCE Biology Question Thread
« Reply #12080 on: October 16, 2019, 09:16:26 pm »
+6
Thank you ssillyssnakes and Erutepa!  ;D It makes so much sense now! I really appreciate all your help.

I had more questions to ask from the 2009 Biology Exam 2.
 
4 a i Describe how this fossil could have formed. 1 mark
I wrote that the bird could have fallen into mud which would have hardened over time. Would this get me the mark? How do you know how much detail to put because the answer says 'rapidly buried by sediment' and hidden from scavengers with other points as well and it's only 1 mark.
I must admit that fossilisation and what not was my least favourite bits of bio, and as such were my weakest areas.
However, when talking about fossilisation, I was always told (by my teacher) that there were 2 critical conditions:
1. Absence of oxygen to prevent decomposition (i.e. from a rapid burial --> gradual burials will still allow for decomposition)
AND
2. Fossil needs to be undisturbed (i.e. by being hidden from scavengers)
Even for a 1 mark question, I would state these two conditions.
This could be misguided, but that's what I have learned
4 b ii Explain how isolation can result in speciation
The answer said to include that there was different genetic variation in the two groups but I was wondering why? All the questions I've done with allopatric speciaion have never included that phrase, including VCAA ones.
You do need genetic variation/different mutation within the two groups. This is important because natural selection requires genetic variation in order to select for advantageous traits. If the population had no genetic variability/no mutations present, speciation would not occur.
Looking at answers from 2016, VCAA do again state that it is necessary for genetic variation to existing within the population in order for speciation to occur. As such, I would recommend including that in your response.

From the same exam, I don't understand questions 7 b and e. I attempted it but I got it wrong and so I don't think I interpreted the questions properly? I'm not sure why VCAA's answer is correct and how they got that?
This appears to be examining content outside of the current study design. Remember that when doing old exams, you will run into stuff that is no longer relevant to the course.

hey guys i just had a question from 2010 exam 1

question 23 multiple choice
i answered enzyme K but enzyme J is the answer. i was just wondering what makes enzyme J any more correct? they are both in an alkaline environment just with different optimum temperature ranges. from what i thought, washing machines washed clothes with hot water therefore this would make enzyme K more correct.

thanks in advance
This is a very weird question. I do agree with Evolio in their reasoning though - If you know about laundry, you can do warm and cold washes, so it makes sense that you would choose the enzyme with the wider temperature range.
Perhaps this is VCAA's way of telling students that they should be doing their own washing haha
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Evolio

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Re: VCE Biology Question Thread
« Reply #12081 on: October 19, 2019, 05:03:14 pm »
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Thank you Erutepa for all the help!  ;D

I had some questions from the 2008 Exam 2 I wanted to ask.

4a.
Is this relevant to the current study design?
If so, this is what I wrote:
Factors include whether the sailors have a genetic predisposition to those genetic disorders. For example, if there is family history of the disorder and it may have been passed down.
This is part of my answer and I was wondering whether this was valid for the question?

7c
I wrote that a river may have been created by heavy rainfall separating the populations which is relatively permanent. Would this be considered correct?

8d
I wrote that they had conflict and had competition between them for resources such as food. Is this a valid point? Would I get a mark for this?


ssillyssnakes

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Re: VCE Biology Question Thread
« Reply #12082 on: October 19, 2019, 05:12:51 pm »
+8


Thank you Erutepa for all the help!  ;D

I had some questions from the 2008 Exam 2 I wanted to ask.

4a.
Is this relevant to the current study design?
If so, this is what I wrote:
Factors include whether the sailors have a genetic predisposition to those genetic disorders. For example, if there is family history of the disorder and it may have been passed down.
This is part of my answer and I was wondering whether this was valid for the question?

7c
I wrote that a river may have been created by heavy rainfall separating the populations which is relatively permanent. Would this be considered correct?

8d
I wrote that they had conflict and had competition between them for resources such as food. Is this a valid point? Would I get a mark for this?

4(a) seems to be relevant to the study design, although some of their (many) suggested answers dont include information we need to know now. Your answer seems to fit within their suggested answer "comparison of chromosomes (or genetic information) between parents and offspring". Obviously you need 2 more points to get 3 marks but that would be worth 1.

7(c) Whilst I would consider that as permanent, the examiners report does state that flooding would not be permanent (even if that flooding resulted in a lost lasting river, I assume) so I personally wouldnt give the mark. In an actual exam, I think it would depend on the examiner you get as to whether or not that would be considered as valid.

8(d) Your point would be valid, even though it isnt an example answer. I think anything reasonable would apply
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radiant roses

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Re: VCE Biology Question Thread
« Reply #12083 on: October 19, 2019, 05:57:56 pm »
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Hi, I have a question.
How can interbreeding occur amongst different early human species like the Denisovans/Neanderthals and modern humans if species are not meant to be able to interbreed? Because in allopatric speciation, when different species meet after being separated, they cannot produce fertile , viable offspring

ssillyssnakes

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Re: VCE Biology Question Thread
« Reply #12084 on: October 19, 2019, 06:10:32 pm »
+4
Hi, I have a question.
How can interbreeding occur amongst different early human species like the Denisovans/Neanderthals and modern humans if species are not meant to be able to interbreed? Because in allopatric speciation, when different species meet after being separated, they cannot produce fertile , viable offspring
Because speciation isnt an instant process, often times that definition can be a little blurry or confusing when talking about instances like that. Whilst if we compare modern homo sapiens to homo denisovans or neanderthalensis, we are different species, but ancient "homo sapiens" probably were probably also in the same species as denisovans and Neanderthals.

Speciation takes a long time so you get these kinds of cases where it becomes difficult to mark were one species evolves into two.

The main important thing for VCE is to understand the general definition and requirements for speciation, and also know that early Sapiens, Neanderthals, and Denisovans were all once one species
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Genshai

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Re: VCE Biology Question Thread
« Reply #12085 on: October 19, 2019, 09:03:12 pm »
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Hello,
i have a question (or two?) about apoptosis :)
Is it the cell that undergoes apoptosis the one that signals for phagocytes? and is this with cytokines?
- thank you in advance !!!
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BitcoinEagle

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Re: VCE Biology Question Thread
« Reply #12086 on: October 19, 2019, 09:08:12 pm »
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Hello everyone,
I've just attempted the QAT VCE Biology written examination from 2018. I had some multiple-choice questions that I wasn't sure of. Could you guys have a look and let me know whether there is a problem in the actual test?

Production of mRNA would begin at the region of the DNA starting at the:
a) operon
b) DNA polymerase binding site
c) promoter region
d) Start codon

D is said to be the right answer although I thought at a DNA strand does not have codons? Is this a mistake in the test?

Another question is this one:

Which statement with regards to enzyme inhibition is correct?
a) Poisons can be irreversible competitive inhibitors
b) Non-competitive inhibition is permanent
c) All competitive inhibition is reversible.
d) Non-competitive inhibits bind to the active site.

Is this something that we need to know for the exam? I thought that the answer was b as this leads to a permanent change in the tertiary structure of an enzyme and hence permanently changes it's function.

Finally, I found this one a bit vague:

What process allows the comparison of DNA of different species to be made?
a) Comparative anatomy
b) DNA-DNA hybridization
c) Polymerase Chain reaction
d) Molecular Clock

I answered D, but the answer is said to be B. Would both answers work?

Thanks everyone.
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BitcoinEagle

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Re: VCE Biology Question Thread
« Reply #12087 on: October 19, 2019, 09:11:39 pm »
+1
Hello,
i have a question (or two?) about apoptosis :)
Is it the cell that undergoes apoptosis the one that signals for phagocytes? and is this with cytokines?
- thank you in advance !!!

Yes, from what I know, apoptosis undergoes the following stages:
Caspases are activated.
Cleaving of proteins and DNA.
Destruction of mitochondria.
Blebbing of contents.
Forming of apoptotic bodies.
Secretion of cytokines to attract phagocytes.

This is done by the cell and with cytokines (which are signaling molecules within the immune system)
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PhoenixxFire

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Re: VCE Biology Question Thread
« Reply #12088 on: October 19, 2019, 09:28:34 pm »
+11
4(a) seems to be relevant to the study design, although some of their (many) suggested answers dont include information we need to know now. Your answer seems to fit within their suggested answer "comparison of chromosomes (or genetic information) between parents and offspring". Obviously you need 2 more points to get 3 marks but that would be worth 1.
Although none of the information in those suggested answers is directly in the study design, it could come under the part of experimental design about controlled variables and you could still get questions that expect you to come up with that type of answer.

8d
I wrote that they had conflict and had competition between them for resources such as food. Is this a valid point? Would I get a mark for this?
That isn't a reason for interbreeding to not occur. You need to talk about a type of reproductive isolation (they are in the same location at the same time so that's the type of isolation that must be occuring).

Hi, I have a question.
How can interbreeding occur amongst different early human species like the Denisovans/Neanderthals and modern humans if species are not meant to be able to interbreed? Because in allopatric speciation, when different species meet after being separated, they cannot produce fertile , viable offspring
The short answer is that our definition of a species isn't perfect. Although we call them different species, they don't really meet the criteria for it.

Because speciation isnt an instant process, often times that definition can be a little blurry or confusing when talking about instances like that. Whilst if we compare modern homo sapiens to homo denisovans or neanderthalensis, we are different species
But if ancient homo sapiens could interbreed with denisovans and neanderthals, and modern homo sapiens can't, then are modern and ancient homo sapiens really the same species? (Biology is complicated and doesn't have clear divisions haha)

Hello,
i have a question (or two?) about apoptosis :)
Is it the cell that undergoes apoptosis the one that signals for phagocytes? and is this with cytokines?
- thank you in advance !!!
There are a lot of different things that signal for phagocytes depending on why the cell is undergoing apoptosis, but yes the cell will do it too. Cytokines is very non-specific. It's not really any different than saying "immune signals" but don't worry about it, you don't need to know the specifics.

Hello everyone,
I've just attempted the QAT VCE Biology written examination from 2018. I had some multiple-choice questions that I wasn't sure of. Could you guys have a look and let me know whether there is a problem in the actual test?

Production of mRNA would begin at the region of the DNA starting at the:
a) operon
b) DNA polymerase binding site
c) promoter region
d) Start codon

D is said to be the right answer although I thought at a DNA strand does not have codons? Is this a mistake in the test?
Yeah, that answer would be correct for the production of a polypeptide chain, not for mRNA.

Another question is this one:

Which statement with regards to enzyme inhibition is correct?
a) Poisons can be irreversible competitive inhibitors
b) Non-competitive inhibition is permanent
c) All competitive inhibition is reversible.
d) Non-competitive inhibits bind to the active site.

Is this something that we need to know for the exam? I thought that the answer was b as this leads to a permanent change in the tertiary structure of an enzyme and hence permanently changes it's function.
A is the correct answer, but this is an unreasonable question. You're not specifically taught about poisons in VCE, and you are taught that non-competitive inhibition is permanent (this isn't actually true).

Finally, I found this one a bit vague:

What process allows the comparison of DNA of different species to be made?
a) Comparative anatomy
b) DNA-DNA hybridization
c) Polymerase Chain reaction
d) Molecular Clock

I answered D, but the answer is said to be B. Would both answers work?

Thanks everyone.
The molecular clock just refers to the standard rate of mutation. You can use this to approximate how long ago species diverged from a common ancestor but it is not a method of comparing the DNA of species.
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BitcoinEagle

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Re: VCE Biology Question Thread
« Reply #12089 on: October 19, 2019, 09:41:49 pm »
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Although none of the information in those suggested answers is directly in the study design, it could come under the part of experimental design about controlled variables and you could still get questions that expect you to come up with that type of answer.
That isn't a reason for interbreeding to not occur. You need to talk about a type of reproductive isolation (they are in the same location at the same time so that's the type of isolation that must be occuring).

The short answer is that our definition of a species isn't perfect. Although we call them different species, they don't really meet the criteria for it.

But if ancient homo sapiens could interbreed with denisovans and neanderthals, and modern homo sapiens can't, then are modern and ancient homo sapiens really the same species? (Biology is complicated and doesn't have clear divisions haha)

There are a lot of different things that signal for phagocytes depending on why the cell is undergoing apoptosis, but yes the cell will do it too. Cytokines is very non-specific. It's not really any different than saying "immune signals" but don't worry about it, you don't need to know the specifics.

Yeah, that answer would be correct for the production of a polypeptide chain, not for mRNA.
A is the correct answer, but this is an unreasonable question. You're not specifically taught about poisons in VCE, and you are taught that non-competitive inhibition is permanent (this isn't actually true).
The molecular clock just refers to the standard rate of mutation. You can use this to approximate how long ago species diverged from a common ancestor but it is not a method of comparing the DNA of species.

Brilliant! This makes so much sense, thanks PhoenixxFire!
 :)
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