ATAR Notes: Forum
Archived Discussion => QCE Exam Discussion 2020 => Exam Discussions => New South Wales => Science Exams => Topic started by: s110820 on October 15, 2020, 04:50:37 pm
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Hey everyone,
The Biology External Exam is fast approaching (someone please do the maths me as to when the exam actually is). How are you guys feeling about this exam? What was your favourite topic in Unit 3? What was your favourite topic in Unit 4? Did you enjoy studying Biology, if so, why? Sorry if it's a lot of questions, I just wanted to start a conversation on this board and hopefully, keep this conversation rolling as the big day draws nearer.
Keep studying and look after yourself,
Darcy Dillon.
P.S. I was also thinking of creating more specific topics on this board such as a topic for each individual topic in the exam, study preparation and what we can do to mentally prepare ourselves for the big day. If you guys have any other ideas, feel free to add more topics to this board as I'm sure the entire QCE community would really appreciate it :)
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I was wondering if we are meant to know about point and frameshift mutations as on the syllabus it says we dont need to know their effect? :'(
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I was wondering if we are meant to know about point and frameshift mutations as on the syllabus it says we dont need to know their effect? :'(
Hey Babo,
I would study the point and frameshift mutations (& their effects) just in case. A few questions based on frameshift and point mutations popped up on a few of my mock exams, so I think that it would be better to be safe than sorry. Also, have you heard about how to answer the "compare" types of questions? There's a specific trick to it that not many schools know about because it's not specified in the syllabus either.
Hopefully, that helps :)
Have a great week and kind regards,
Darcy Dillon.
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I was wondering if we are meant to know about point and frameshift mutations as on the syllabus it says we dont need to know their effect? :'(
Hey,
welcome to the forums!
you should know about them, just not about their effects in terms of how those mutations impact translation. I.e. you should know what point and frameshift mutations are but you don't need to know about the missense, nonsense, or silent impacts
I hope this helps :)
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Alright thankyou! and for pedigrees, they have not been mentioned by the syllabus, yet they came in the mocks..
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Hey,
welcome to the forums!
you should know about them, just not about their effects in terms of how those mutations impact translation. I.e. you should know what point and frameshift mutations are but you don't need to know about the missense, nonsense, or silent impacts
I hope this helps :)
Hey Bri,
I have to disagree with you a little bit on what you said about the mutations - we do actually need to know the difference betweens missense, nonense and silent mutations as well as their specific impacts on biological processes. I definitely had a few questions on my mock exams about these types of mutations so again, I think it's better to be safe than sorry.
Hopefully, that helps :)
Have a great week and kind regards,
Darcy Dillon.
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Alright thankyou! and for pedigrees, they have not been mentioned by the syllabus, yet they came in the mocks..
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Hey Bri,
I have to disagree with you a little bit on what you said about the mutations - we do actually need to know the difference betweens missense, nonense and silent mutations as well as their specific impacts on biological processes. I definitely had a few questions on my mock exams about these types of mutations so again, I think it's better to be safe than sorry.
Hopefully, that helps :)
Have a great week and kind regards,
Darcy Dillon.
Hey Darcy,
I would always rather be challenged if that means that people can get more accurate info or things can be clarified so thank you.
The reason I have said missense, nonsense etc. does not need to be known is because in the syllabus this is explicitly stated.
Page 56: https://www.qcaa.qld.edu.au/downloads/senior-qce/syllabuses/snr_biology_19_syll.pdf
" Students are not required to identify the effects of mutations (i.e. silent, missense, nonsense)"
At least in other states, I have noticed in the past issues with mock exams where the syllabus has not been fully followed and questions are not completely indicative of what would actually appear on an exam. The most trusted source of information should always be QCAA and especially current QCAA documents such as the syllabus, then other material which may have been produced in support of this.
Ultimately, the difference between missense, nonsense and silent is not hard to learn so if anyone would feel more comfortable in learning these I'm not going to say you can't; however, the syllabus provides clear instruction about this being unnecessary.
I hope you have a great week too :)
Edit:
Alright thankyou! and for pedigrees, they have not been mentioned by the syllabus, yet they came in the mocks..
From the syllabus:
"predict frequencies of genotypes and phenotypes using data from probability models (including frequency histograms and Punnett squares) and by taking into consideration patterns of inheritance for the following types of alleles: autosomal dominant, sex linked and multiple"
(page 56)
imo it is not unreasonable for patterns of inheritance to be shown in a pedigree and for you to be expected to interpret those.
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Thanks bri :)
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Hey Darcy,
I would always rather be challenged if that means that people can get more accurate info or things can be clarified so thank you.
The reason I have said missense, nonsense etc. does not need to be known is because in the syllabus this is explicitly stated.
Page 56: https://www.qcaa.qld.edu.au/downloads/senior-qce/syllabuses/snr_biology_19_syll.pdf
" Students are not required to identify the effects of mutations (i.e. silent, missense, nonsense)"
At least in other states, I have noticed in the past issues with mock exams where the syllabus has not been fully followed and questions are not completely indicative of what would actually appear on an exam. The most trusted source of information should always be QCAA and especially current QCAA documents such as the syllabus, then other material which may have been produced in support of this.
Ultimately, the difference between missense, nonsense and silent is not hard to learn so if anyone would feel more comfortable in learning these I'm not going to say you can't; however, the syllabus provides clear instruction about this being unnecessary.
I hope you have a great week too :)
Edit:
From the syllabus:
"predict frequencies of genotypes and phenotypes using data from probability models (including frequency histograms and Punnett squares) and by taking into consideration patterns of inheritance for the following types of alleles: autosomal dominant, sex linked and multiple"
(page 56)
imo it is not unreasonable for patterns of inheritance to be shown in a pedigree and for you to be expected to interpret those.
Hey Bri,
Thank you so much for your lovely and thoughtful response! I really appreciated understanding your perspective. However, the mock exams I mentioned in my previous response also included the QCAA mock exams, which is why I advised @babo to study these types of mutations and their effects just in case.
Hopefully, that helps to clarify your thoughts :)
Have a great week and kind regards,
Darcy Dillon.
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Hey Bri,
Thank you so much for your lovely and thoughtful response! I really appreciated understanding your perspective. However, the mock exams I mentioned in my previous response also included the QCAA mock exams, which is why I advised @babo to study these types of mutations and their effects just in case.
Hopefully, that helps to clarify your thoughts :)
Have a great week and kind regards,
Darcy Dillon.
Hey Darcy,
No worries at all!
I wonder whether the mocks were made before the syllabus was finalised or something. In any event, while I trust the syllabus as the most important document guiding what's assessable I completely understand why you'd be cautious given the mocks - especially Queensland being new to externals as well - and ultimately if learning this small topic helps you feel more comfortable I can certainly understand why you would do that and advise others accordinly. I'm glad we've had this convo rather than staying silent so that people can make an informed decision when it comes to their study :)
Best of luck to you too!
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Hi Forum,
I’ve been trying to revise the law of independent assortment and the law of segregation that Mendel proposed after finishing the inheritance experiments.
I’ve read through the definitions and I understand what they state but I’m not sure how to apply it to the context. So my question is:
What does the law of segregation and the law of independent assortment actually mean?
And how do these laws fit into inheritance?
And how do these laws assist genetic variation?
Thank you!
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Hi Forum,
I’ve been trying to revise the law of independent assortment and the law of segregation that Mendel proposed after finishing the inheritance experiments.
I’ve read through the definitions and I understand what they state but I’m not sure how to apply it to the context. So my question is:
What does the law of segregation and the law of independent assortment actually mean?
And how do these laws fit into inheritance?
And how do these laws assist genetic variation?
Thank you!
Hi!
So the point of it is this: each diploid organism (e.g. us) has 2 copies of each gene.
The law of segregation is about how when someone makes a gamete, that gamete gets contains one of the two copies, and so the offspring formed by one gamete from each parent then has one copy of each gene from each parent. This means that the offspring isn't a genetically identical copy to either of its parents nor just an "average" of their traits (can you see how this fits into genetic variation?).
The law of independent assortment tells us that the probability of inheriting one allele doesn't change based on what other alleles we've inherited (note that this is not true for genes on the same chromosome!). Without this, you'd expect much less diversity in what combinations of alleles the offspring has. Independent assortment is actually really important for making it so that we can remove deleterious (bad) alleles from the population without making the whole lineage go extinct, and that's thought to be one major reason why so many species have sexual reproduction. This might be a little confusing, lmk if you want a diagram or something to clear this up more :)
I hope this helps!
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Hi!
So the point of it is this: each diploid organism (e.g. us) has 2 copies of each gene.
The law of segregation is about how when someone makes a gamete, that gamete gets contains one of the two copies, and so the offspring formed by one gamete from each parent then has one copy of each gene from each parent. This means that the offspring isn't a genetically identical copy to either of its parents nor just an "average" of their traits (can you see how this fits into genetic variation?).
The law of independent assortment tells us that the probability of inheriting one allele doesn't change based on what other alleles we've inherited (note that this is not true for genes on the same chromosome!). Without this, you'd expect much less diversity in what combinations of alleles the offspring has. Independent assortment is actually really important for making it so that we can remove deleterious (bad) alleles from the population without making the whole lineage go extinct, and that's thought to be one major reason why so many species have sexual reproduction. This might be a little confusing, lmk if you want a diagram or something to clear this up more :)
I hope this helps!
Thank you, this helped me a lot. The textbook has a very plain definition, so this really cleared it up.
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Hey everyone,
So bio is done and I really need an answer for the last question on paper 2. I am really nervous because it was worth a lot and I am reallllllyyyy sure they did not give enough information.
The question stated that the 3 time points were leading up to the speciation now, if the speciation occurred like the gene flow was in the most recent time point, it would have been parapatric speciation right? Because the population wasn’t isolated (there was still gene flow between two sub populations).
But in theory, if the speciation occurred later, the gene flow could have been fully reduced because that was the trend, making the population isolated, and the answer being allopatric speciation!
The question says the data is “leading up to the speciation event” but without knowing when the population developed reproductive isolation mechanisms, it could either be parapatric or allopatric (not sympatric because gene flow stopped between the target population and populations B and C)
Anyway,
What did you all think of that question? Am I being crazy or was there actually some critical information missing?
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Hey everyone,
So bio is done and I really need an answer for the last question on paper 2. I am really nervous because it was worth a lot and I am reallllllyyyy sure they did not give enough information.
The question stated that the 3 time points were leading up to the speciation now, if the speciation occurred like the gene flow was in the most recent time point, it would have been parapatric speciation right? Because the population wasn’t isolated (there was still gene flow between two sub populations).
But in theory, if the speciation occurred later, the gene flow could have been fully reduced because that was the trend, making the population isolated, and the answer being allopatric speciation!
The question says the data is “leading up to the speciation event” but without knowing when the population developed reproductive isolation mechanisms, it could either be parapatric or allopatric (not sympatric because gene flow stopped between the target population and populations B and C)
Anyway,
What did you all think of that question? Am I being crazy or was there actually some critical information missing?
I haven't seen the exam question but I am going to point out that from how you've written your post it seems like regardless of whether you wrote the target answer or not you will have shown good biological thinking. Fingers crossed!
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I haven't seen the exam question but I am going to point out that from how you've written your post it seems like regardless of whether you wrote the target answer or not you will have shown good biological thinking. Fingers crossed!
Yea that’s what I’m hoping :/, but looking at the marking guide for the practice exam, the points are distributed very plainly on just “stating this” and “explaining that”, I hope I did ok.
I am very interested in seeing what other students answered, that question really confused me
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Biology exam wasn't bad. It was interesting and kind of fun?
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But in theory, if the speciation occurred later, the gene flow could have been fully reduced because that was the trend, making the population isolated, and the answer being allopatric speciation!
Anyway,
What did you all think of that question? Am I being crazy or was there actually some critical information missing?
Yea that's what I thought too. If we were to see future generations pass the third time point I'm sure it would have lead to allopatric speciation with niche D eventually becoming isolated from the others.
Like Bri said, I guess there is not really a right or wrong answers as long as you can justify your position?
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Yea that's what I thought too. If we were to see future generations pass the third time point I'm sure it would have lead to allopatric speciation with niche D eventually becoming isolated from the others.
Like Bri said, I guess there is not really a right or wrong answers as long as you can justify your position?
You have no idea how relieved I am to see that I was not the only one who thought of this! I was so worried!
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Yea that's what I thought too. If we were to see future generations pass the third time point I'm sure it would have lead to allopatric speciation with niche D eventually becoming isolated from the others.
Like Bri said, I guess there is not really a right or wrong answers as long as you can justify your position?
I mean, (again I haven't seen the exam so kinda hard for me to predict) it could very well be the case that there is a right answer but if it's a q with lots of marks then most of those won't be for saying which type but rather communicating your understanding of the relevant biological context.
Also worth pointing out that you generally don't need to full mark exams to get the top score.
Biology exam wasn't bad. It was interesting and kind of fun?
I remember in my bio exam I saw a question on evolution of tortoises during reading time and from that I was like full hype and ready to go. Strange how exams can be really intimidating things but sometimes also enjoyable to actually do?
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Biology exam wasn't bad. It was interesting and kind of fun?
I think the biology exam was fine, I got confused by the last question on paper 2 because there are two possible ways the answer could have been argued, but apart from that it was fine.
I was kind of disappointed that there wasn’t a question on either of the two types of gametogenesis or on Mendel’s laws, I put a lot of emphasis on those while studying :(
I was so happy when I saw there was a question on DNA replication tho, I think I went into a little too much detail
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so how i approached that question was that i
1. interpreted the diagram the question gave me and told what happened ant what time + what change
2. then i went on stating that it was allopatric speciation since 1. it is not sympatric speciation since sympatric speciation often occurs when a mutation (etc. polyploidy...) occurs and reproductive isolation would've occurred in approx 1 generation while teh diagram given shows gradual isolation of population D 2. it is not parapatric speciation since no necessary geographical barriers occur in parapatric speciation to absolutely stop / cease the gene flow, while the diagram given show that the gene flow ceases absolutely by wiping out the whole arrow (instead of making it thinner or sth...)
Bro i dunno if im correct or not....
Like what do u guys think?
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so how i approached that question was that i
1. interpreted the diagram the question gave me and told what happened ant what time + what change
2. then i went on stating that it was allopatric speciation since 1. it is not sympatric speciation since sympatric speciation often occurs when a mutation (etc. polyploidy...) occurs and reproductive isolation would've occurred in approx 1 generation while teh diagram given shows gradual isolation of population D 2. it is not parapatric speciation since no necessary geographical barriers occur in parapatric speciation to absolutely stop / cease the gene flow, while the diagram given show that the gene flow ceases absolutely by wiping out the whole arrow (instead of making it thinner or sth...)
Bro i dunno if im correct or not....
Yeah you make some great points for allopatric speciation. But for all we know, the speciation could have occurred during time period 3, or, the trend could have continued until there was no gene flow. It would have been great to know when the actual speciation event occurred. I was going to say allopatric speciation but because there was still gene flow I settled for parapatric. It could have been parpatric, of course we do not know anything about the environment of the species, but if the two niches are lets say, on other sides of a mountain, but still in the same geographic range, there could be complete blockage of gene flow between those two niches
Both types of speciation can be argued with evidence, I just shut myself off from any emotions or paranoia and thought to myself, there is gene flow, so it would not be allopatric.
Then again, not knowing when the speciation event occurred really threw things around for me.
One more thing, it is important to note that even though the population was split up into 4 niches, that (in plain terms) they are still one population. Even though it appeared that there was complete isolation, if you consider the 4 groups as one population, it was reduced gene flow, and not complete isolation. Isolation between niches: yes, isolation between populations: no
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ohhh yeah that makes sense hhh
i kinda went around that point by saying it is geographically isolated with population C & D? (like i was imagining all the populations are connected by bridges and the bridge between D with C & B collapsed)
I get what u are saying with the parapatric speciation....maybe im wrong hmmm
But i still dont get it when you say two niches are on other sides of a mountain, but still in the same geographic range, there could be complete blockage of gene flow between those two niches--isnt that already a geographical barrier that makes it a allopatric isolation? (im really confused now hahahaha
Anyway, thanks for your reply :)
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ohhh yeah that makes sense hhh
i kinda went around that point by saying it is geographically isolated with population C & D? (like i was imagining all the populations are connected by bridges and the bridge between D with C & B collapsed)
I get what u are saying with the parapatric speciation....maybe im wrong hmmm
But i still dont get it when you say two niches are on other sides of a mountain, but still in the same geographic range, there could be complete blockage of gene flow between those two niches--isnt that already a geographical barrier that makes it a allopatric isolation? (im really confused now hahahaha
Anyway, thanks for your reply :)
That’s where clinal variation comes in. There would be indirect gene flow (idk if that’s the right term to use)
Basically imagine 3 populations connected by bridges
A———-B——-C
Now, there is no gene flow between C and A, but there is gene flow between B and A, that’s kind of what I thought when answering the question. Yes, there is somewhat isolation, but it’s still just one large population that is connected by reduced gene flow.
Or see it this way, a population spreads from east QLD to west QLD. Individuals in the west won’t breed with individuals in the east, but they both bread with individuals in the middle of QLD. Technically, east and west populations would be isolated from each other, yet there is still gene flow because they are still one unified population spread over a wide geographic range.
It appears everyone else settled for allopatric speciation :( which makes me think I am wrong, because yea, it makes sense if you assume that eventually the gene flow completely stops, but at that point in time, there was still gene flow.
I think I’m just gonna have to accept that I looked too much into it :(.
If the question stated,
If speciation occurred during time period 3..... it would be parapatric
But if it stated,
If speciation occurred in future time periods.... it would have been allopatric because as you said, the reduced gene flow would have eventually stopped
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That’s where clinal variation comes in. There would be indirect gene flow (idk if that’s the right term to use)
Basically imagine 3 populations connected by bridges
A———-B——-C
Now, there is no gene flow between C and A, but there is gene flow between B and A, that’s kind of what I thought when answering the question. Yes, there is somewhat isolation, but it’s still just one large population that is connected by reduced gene flow.
Or see it this way, a population spreads from east QLD to west QLD. Individuals in the west won’t breed with individuals in the east, but they both bread with individuals in the middle of QLD. Technically, east and west populations would be isolated from each other, yet there is still gene flow because they are still one unified population spread over a wide geographic range.
It appears everyone else settled for allopatric speciation :( which makes me think I am wrong, because yea, it makes sense if you assume that eventually the gene flow completely stops, but at that point in time, there was still gene flow.
I think I’m just gonna have to accept that I looked too much into it :(.
If the question stated,
If speciation occurred during time period 3..... it would be parapatric
But if it stated,
If speciation occurred in future time periods.... it would have been allopatric because as you said, the reduced gene flow would have eventually stopped
Wow thanks for your explanation!!!
Now this makes sense (but i forgot to assume the 'eventually in the long term' thing so that remains a risk for me :) and my justification for not parapatric doesn't seem to be enough hhhhh)
Nah but i think as long as u justify your answer it will be marked correct :) so relax bro
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Wow thanks for your explanation!!!
Now this makes sense (but i forgot to assume the 'eventually in the long term' thing so that remains a risk for me :) and my justification for not parapatric doesn't seem to be enough hhhhh)
Nah but i think as long as u justify your answer it will be marked correct :) so relax bro
Yea I hope I get some marks but the sample assessment marking guide has very clear mark allocations,
The Marking guide isn’t
7-provides cleat justified viewpoint
6-Represents a viewpoint with evidence etc
It’s more like,
1 mark=recognise it’s allopatric
1 mark=explain allopatric speciation
1 mark= Use evidence to prove it as allopatric
And so on...
(That was the marking guide for the sample assessment so idk if it will be like this in the actual external exam)