ATAR Notes: Forum
Archived Discussion => Mathematics/Science/Technology => 2014 => Exam Discussion => Victoria => Biology => Topic started by: Scooby on November 01, 2014, 04:37:21 am
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Hey everyone!
I've written up some suggested solutions for the short answer section of yesterday's exam if you want to have a look!
If you do, and you find that for certain questions you wrote something really different to what I did, don't be disheartened - there will definitely be things they end up accepting for certain questions that I haven't included :)
If you disagree with anything I've written, definitely let me know!
Sorry that Q2 and part of Q12 are missing - the pictures I used were blurry and I had trouble reading the questions. Once I can get a hold of some clearer pictures, I'll go back and add in some answers for them too
Regardless of what happens on results day, you should all be proud of the effort you've put into what is a really tough subject over this year. Congratulations on finishing Bio! :)
UPDATE:
12b
i)
• Variation existed in a population of M. africanavus
• Natural selection acted on this population over millions of years (or a description of this process)
• If members of this population would no longer be able to mate (producing fertile offspring) with members of the initial M.africanavus population, it is considered as consisting of a different species (ie. M. primigenius)
ii)
• Major environmental changes occurred
• M. primigenius was unable to adapt to these changes and extinction occurred
• E. maximus was able to adapt this change, possibly because of a greater genetic diversity than M. primigenius
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Hey Scooby, for question 9A do you still think I can get marks if I wrote polypeptide instead of protein?
Also for 11C, would the use of tools by freeing up hands and more efficient travel --> more migration be acceptable?
Finally, would mutations be another source of variation in males for question 6b?
Edit: Forgot to say, thanks for the (mock) solutions!
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Loved the answer for Q 11 bii :p
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Thanks Scooby! Yeah basically same questions as dan frank. What do you think?
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Hey Scooby, for question 9A do you still think I can get marks if I wrote polypeptide instead of protein?
Also for 11C, would the use of tools by freeing up hands and more efficient travel --> more migration be acceptable?
Finally, would mutations be another source of variation in males for question 6b?
Edit: Forgot to say, thanks for the (mock) solutions!
Yeah, for 11C, your answer is better than mine ahah, I had trouble thinking of something decent but yeah, they'll accept that
Yup, the question asked for how it "can" occur, so I'd say they'll accept mutation as another source of variation
Loved the answer for Q 11 bii :p
ahah thanks, that question was definitely an interesting one
Thanks Scooby! Yeah basically same questions as dan frank. What do you think?
It was a fair exam, but there were definitely some challenging question in there. The A+ cut off should drop a fair bit compared with last year - there was definitely a step up in difficulty this year!
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Yeah, for 11C, your answer is better than mine ahah, I had trouble thinking of something decent but yeah, they'll accept that
Yup, the question asked for how it "can" occur, so I'd say they'll accept mutation as another source of variation
Cheers, but could you please answer my first question? Really panicking that I threw a mark away... :(
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Hey Scooby, for question 9A do you still think I can get marks if I wrote polypeptide instead of protein?
Woops, forgot to answer this part - yeah, you should still get a mark for that :)
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Legend.
But... I've got a few queries if someone won't mind answering them:
4c. I drew 3 antibodies attached each to one antigen on the same pathogen and another antibody moving towards an antigen of different pathogen (drew an arrow from the binding site to the antigen saying the antibody moves to bind there etc.) Is that sufficient?
4cii. Wrote macrophages instead of phagocytes... Still right?
5c. Just wrote passive cause the mother doesn't produce antibodies herself but not sure if this is in depth enough.
9b. Said one chromosome number doesn't have a homologous pair when compared rather than it only has 45 chromosomes. This is still acceptable yeah?
11c. Is 'Choose a protein common to all species under analysis.' absolutely essential?
Sorry for the long post. Thanks
4 ci. Yeah, that's definitely fine
4 cii. Yup, macrophages will definitely be accepted too
5c. That should be alright. I think how it'll go is that they'll give one mark for identifying that it's passive immunity, and then the second mark for saying that she doesn't manufacture her own antibodies/memory cells OR that protection ceases after the treatment is discontinued
9b. Yup, should be fine
11c. Choosing a protein common to all the species analysed is an important part of the procedure, of course (you don't want to extract different proteins from each of the species, or there'll be no point), but I'll be surprised if you're penalised just because you didn't state that explicitly
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I've got a clearer copy of the exam now, so I'll have solutions for the questions I missed posted soon! :)
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For question 10.A would I be wrong if I mentioned the sex of the bee in the phenotype?
I put 25% for Red Male, 25% Black male...etc.
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@Heymanhru
Yeah you'll be ok with that
Hey Scooby,
Do you think they'll accept a description of allopatric speciation for 12bi? Ie:
- populations of M. africanavus become isolated from eachother preventing gene flow
- these populations faced different selection pressures, hence developing different phenotypes to suit these pressures
- eventually these populations were so different that they could no longer interbreed and produce fertile offspring when brought back togther
- hence a new species was formed (M. primigenius)
Also for 12bii, do you think they'd accept this
- M primigenius faced extreme selection pressures (such as climate change and human hunting) that the E maximus was not subjected to
- E maximus is more suited to its environment
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For question 10.A would I be wrong if I mentioned the sex of the bee in the phenotype?
I put 25% for Red Male, 25% Black male...etc.
You're supposed to mention the sex as it's a part of an organism's phenotype :)
Do you think they'll accept a description of allopatric speciation for 12bi? Ie:
- populations of M. africanavus become isolated from eachother preventing gene flow
- these populations faced different selection pressures, hence developing different phenotypes to suit these pressures
- eventually these populations were so different that they could no longer interbreed and produce fertile offspring when brought back togther
- hence a new species was formed (M. primigenius)
It's not speciation though because the entire species evolves, thus undergoing evolution via natural selection. The two populations wouldn't be able to interbreed technically because only one exists. Theoretically if they were brought back together somehow, yes they would not produce viable offspring, but that's impossible... :-\
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It's not speciation though because the entire species evolves, thus undergoing evolution via natural selection. The two populations wouldn't be able to interbreed technically because only one exists. Theoretically if they were brought back together somehow, yes they would not produce viable offspring, but that's impossible... :-\
So thats 0/3 then? :-\
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So thats 0/3 then? :-\
No! I think you'd definitely still get marks for mentioning different selection pressures. That question was so ambiguous though :\
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No! I think you'd definitely still get marks for mentioning different selection pressures. That question was so ambiguous though :\
Yeah, hopefully they recognise that and accept a wider range of responses.
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For question 10.A would I be wrong if I mentioned the sex of the bee in the phenotype?
I put 25% for Red Male, 25% Black male...etc.
I wrote 1 Red Male, 1 Black male...etc is that okay? I forgot to at least do ¼ or 25% (time constraints didn't help)
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I wrote 1 Red Male, 1 Black male...etc is that okay? I forgot to at least do ¼ or 25% (time constraints didn't help)
If I recall correctly I did the same thing (1:1:1:1), I'm guessing it should be okay :P.
Edit: If you wrote it as in 1 Red Male : 1 Black male : 1 Red Female : 1 Black Female I don't see why it could possibly be wrong, that's what I did anyway lol
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Hope it's acceptable :P
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Thanks for all of these! Could you peles post question 2 as well!? It's been stressing me out!
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If I recall correctly I did the same thing (1:1:1:1), I'm guessing it should be okay :P.
Edit: If you wrote it as in 1 Red Male : 1 Black male : 1 Red Female : 1 Black Female I don't see why it could possibly be wrong, that's what I did anyway lol
I also wrote the same thing :)
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If Katie got it right, we got it right ::)
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If Katie got it right, we got it right ::)
Ahh no, here's hoping :o.
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There was a question regarding the steps and procedures of PCR (Polymerase Chain Reaction). It was a 3 mark question so I assume there are 3 parts to it. I listed each step- explaining what occured at each step including the appropriate temperatures at which the different events occured. However, I am worried that I forgot to mention that the process should be repeated at the end. Do you think I will lose a whole mark for this? Technically speaking though, the question asked how scientists may amplify samples of DNA and even one cycle of PCR would produce 2 new strands of DNA, technically 'amplifying' the original amount... So my question is, do you think I will lose an entire mark although I listed all 3 steps and all important factors correctly?
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For q 11.d (behavioural changes due to bipedalism) could I have said 'instead of being arboreal (living in trees) they now mostly live on the flat grasslands' ?
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There was a question regarding the steps and procedures of PCR (Polymerase Chain Reaction). It was a 3 mark question so I assume there are 3 parts to it. I listed each step- explaining what occured at each step including the appropriate temperatures at which the different events occured. However, I am worried that I forgot to mention that the process should be repeated at the end. Do you think I will lose a whole mark for this? Technically speaking though, the question asked how scientists may amplify samples of DNA and even one cycle of PCR would produce 2 new strands of DNA, technically 'amplifying' the original amount... So my question is, do you think I will lose an entire mark although I listed all 3 steps and all important factors correctly?
This question has been asked before and here was VCAA's answer:
heat DNA to approximately 90 °C or to separate strands
cool to approximately 50 °C or to anneal/attach primers
heat to approx 72 °C or Taq/DNA polymerase copies strands
repeat cycle.
Many students set out clear answers that demonstrated a sound understanding of the process. Many other students
missed out on full marks by not stating that the process needed to be repeated.
Although, this question was out of 4 marks and the one on our exam was maybe out of 3 marks?
But yeah might lose the mark.. but hopefully not because i think i forgot to say repeat cycle as well :(
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For q 11.d (behavioural changes due to bipedalism) could I have said 'instead of being arboreal (living in trees) they now mostly live on the flat grasslands' ?
I think this is a question where VCAA will accept a range of suitable answers. I wrote:
- freed up hands, facilitating use of tools
- more efficient travel, facilitating various migrations
So as long as it makes sense then VCAA will award you marks.
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This question has been asked before and here was VCAA's answer:
heat DNA to approximately 90 °C or to separate strands
cool to approximately 50 °C or to anneal/attach primers
heat to approx 72 °C or Taq/DNA polymerase copies strands
repeat cycle.
Many students set out clear answers that demonstrated a sound understanding of the process. Many other students
missed out on full marks by not stating that the process needed to be repeated.
So yes i think you will. But i think i forgot to say repeat cycle too :(
I only stated the specific temperature for denaturation/heating (step 1) however I did say at cooler temperatures for step 2 and 3. Would that be enough? I did say that the process needed to be repeated.
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I think this is a question where VCAA will accept a range of suitable answers. I wrote:
- freed up hands, facilitating use of tools
- more efficient travel, facilitating various migrations
So as long as it makes sense then VCAA will award you marks.
This is exactly what I wrote..
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This is exactly what I wrote..
What's that they say about great minds?
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Everyone asking about whether you needed to mention the sex of the offspring for one of the monohybrid cross questions - since sex didn't influence the likelihood of the offspring having either trait, I chose not to include it, but you can if you want to, of course, as has been mentioned :)
As for the question about the Woolly mammoths, yeah, it was a ambiguous, but since the question asked for "how" the new species arose (ie. the mechanism of evolution), they were probably looking for you to answer it in the context of natural selection :-\
You'll still get some marks for a description of allopatric speciation though!
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And as for the bepalism question (and the one about Otzi), as long as your answer makes sense, it'll be accepted. They definitely won't be rigid with their marking there :P
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For 12bii, do you think I'll get they marks if I said that the Asiatic elephant lived in an area which didn't have many humans hunting it and in an area with a stable climate which it was fit for while the other did not?
Yup, sounds good to me
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You'll still get some marks for a description of allopatric speciation though!
You think so? I'm doubtful... :-\
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You think so? I'm doubtful... :-\
What'd you include in your answer?
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just a question, do you guys reckon the examiners would start marking our papers already? :o
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What'd you include in your answer?
Pretty much a verbatim allopatric speciation answer:
- Two populations of ancestor species were geographically isolated, preventing gene flow
- They faced different selection pressures, hence developing different phenotypes to suit these pressures
- Eventually their phenotypes were so different that they were unable to interbreed and produce viable, fertile offspring
- Hence the new species (woolly mammoth) was formed
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just a question, do you guys reckon the examiners would start marking our papers already? :o
They've got their training day on the 5th, then mark from the 6th to the 22nd
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Pretty much a verbatim allopatric speciation answer:
- Two populations of ancestor species were geographically isolated, preventing gene flow
- They faced different selection pressures, hence developing different phenotypes to suit these pressures
- Eventually their phenotypes were so different that they were unable to interbreed and produce viable, fertile offspring
- Hence the new species (woolly mammoth) was formed
You'll still get marks for discussing selection pressures, and also for mentioning reproductive isolation
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hey just a quick question, im really confused as to why question 7b. is 273 codons! The question asks how many codons were involved in the coding of this polymer, 273 codons were involved in the translation process, but only 270 were involved in the coding for the actual polymer, because the stop codon doesn't code for an amino acid? Can someone please explain this in depth, really confused haha thank you!!
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hey just a quick question, im really confused as to why question 7b. is 273 codons! The question asks how many codons were involved in the coding of this polymer, 273 codons were involved in the translation process, but only 270 were involved in the coding for the actual polymer, because the stop codon doesn't code for an amino acid? Can someone please explain this in depth, really confused haha thank you!!
To be honest I expect that VCAA will accept a range of answers for this. It said **explain** your response to the question, so as long as you justify why you came to your final number (be it 270 or 273), I think VCAA will award the full 2 marks.
You'll still get marks for discussing selection pressures, and also for mentioning reproductive isolation
Hmm thats really reassuring thanks, honestly thought I'd get a 0/3 for that question.
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To be honest I expect that VCAA will accept a range of answers for this. It said **explain** your response to the question, so as long as you justify why you came to your final number (be it 270 or 273), I think VCAA will award the full 2 marks.
Yes hopefully haha thanks! Overall I didnt feel like I was doing a VCAA exam, the questions weren't VCAA style at all! Hopefully they lower the A+ cut off, just a quick question i know everybody hates these ones, but with rank 1 and 95/110 (considering i marked myself 0 for that question and 0 for the second last question as i put allopatric speciation but with a good explanation), is it possible to still receive a raw score of 40?
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You'll still get marks for discussing selection pressures, and also for mentioning reproductive isolation
Wow really? I answered the same as dankfrank (again :p).
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Yes hopefully haha thanks! Overall I didnt feel like I was doing a VCAA exam, the questions weren't VCAA style at all! Hopefully they lower the A+ cut off, just a quick question i know everybody hates these ones, but with rank 1 and 95/110 (considering i marked myself 0 for that question and 0 for the second last question as i put allopatric speciation but with a good explanation), is it possible to still receive a raw score of 40?
Yup, A+ cut off last year was 93/110. This year I think it might drop to around 88-89/110, so 95/110 will definitely get you a 40+ (probably around 43-44)
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If I get 85/110 or 90/110 on this bio exam, will be able to get 40? :-\
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If I get 85/110 or 90/110 on this bio exam, will be able to get 40? :-\
Depends on your SACs, but based on exam alone I predict that 90 will scrape into the low A+ zone (hence giving you a 40).
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with the crosses, in the past VCAA has required you to state the sex of the resulting offspring from the cross if the sex of each parent is mentioned in the stem of the question or the question.
a key word in that second cross was Purple Male x Lilac Female
even though the gene is not sex-linked, the sex of the parents was mentioned in the question.
a second reason why the second one is more likely to include the sex of the parents in the calculations is because the first one was monohybrid sex linked. why would they waste another question on asking us to do another monohybrid cross? i think they wanted a dihybrid cross
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with the crosses, in the past VCAA has required you to state the sex of the resulting offspring from the cross if the sex of each parent is mentioned in the stem of the question or the question.
a key word in that second cross was Purple Male x Lilac Female
even though the gene is not sex-linked, the sex of the parents was mentioned in the question.
a second reason why the second one is more likely to include the sex of the parents in the calculations is because the first one was monohybrid sex linked. why would they waste another question on asking us to do another monohybrid cross? i think they wanted a dihybrid cross
What did you do?
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with the crosses, in the past VCAA has required you to state the sex of the resulting offspring from the cross if the sex of each parent is mentioned in the stem of the question or the question.
a key word in that second cross was Purple Male x Lilac Female
even though the gene is not sex-linked, the sex of the parents was mentioned in the question.
a second reason why the second one is more likely to include the sex of the parents in the calculations is because the first one was monohybrid sex linked. why would they waste another question on asking us to do another monohybrid cross? i think they wanted a dihybrid cross
If you've got a picture of that question then post it, but I think the reason they included that question was to check if people knew that autosomal traits show no pattern in a particular gender of offspring like sex-linked does. The male and female was a red herring to throw people off and make them write "50% male purple" when really there's no way to tell the gender.
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I just wanted to confirm, does VCAA use the SAC scores that you get at school?
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I just wanted to confirm, does VCAA use the SAC scores that you get at school?
Yup, your teacher sends your results (not just rank) to VCAA. Your moderated mark may end up completely different to what your teacher submits though
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If you've got a picture of that question then post it, but I think the reason they included that question was to check if people knew that autosomal traits show no pattern in a particular gender of offspring like sex-linked does. The male and female was a red herring to throw people off and make them write "50% male purple" when really there's no way to tell the gender.
Well, considering in the stem of the question they included the genotypes of the male and female phenotype, yes you are able to tell the gender.
This requires you to perform a dihybrid unlinked cross, with the gender genotype as the first factor and the colour as the second factor.
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Well, considering in the stem of the question they included the genotypes of the male and female phenotype, yes you are able to tell the gender.
This requires you to perform a dihybrid unlinked cross, with the gender genotype as the first factor and the colour as the second factor.
Pretty sure the gender was just a red herring because the trait is autosomal.
Besides, you don't determine your sex by your genes - its about which chromosome you receive from dad.
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Pretty sure the gender was just a red herring because the trait is autosomal.
Would you not get the mark if you included gender in the phenotype?
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Well, considering in the stem of the question they included the genotypes of the male and female phenotype, yes you are able to tell the gender.
This requires you to perform a dihybrid unlinked cross, with the gender genotype as the first factor and the colour as the second factor.
This is what I did, but no one else seems to have done it so I thought it was wrong. Is it?
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This is what I did, but no one else seems to have done it so I thought it was wrong. Is it?
How could it be a dihybrid cross? Nothing has a 'gene' for gender, its about which chromosome you receive from dad.
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How could it be a dihybrid cross? Nothing has a 'gene' for gender, its about which chromosome you receive from dad.
Yeah, the question didn't specify what the X linked trait was, so we can't assume it was talking about gender. In this case, gender seems irrelevant as the specific trait they asked for was autosomal, which we know is equally likely to be inherited by either male/female.
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How could it be a dihybrid cross? Nothing has a 'gene' for gender, its about which chromosome you receive from dad.
I just did like a cross of the phenotype of the dad, which was like ZZBB maybe I can't remember, and a cross with the mum which was maybe ZYBb (I'm making these up, can't rmemeber).
Then dihybrid cross using these two
So ZZBB X ZYBb
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I just did like a cross of the phenotype of the dad, which was like ZZBB maybe I can't remember, and a cross with the mum which was maybe ZYBb (I'm making these up, can't rmemeber).
Then dihybrid cross using these two
So ZZBB X ZYBb
The Z's and W's weren't genes - they were chromosomes.