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March 29, 2024, 08:10:47 am

Author Topic: Feedback thread for self-marked exams  (Read 7820 times)  Share 

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paulthekiller123

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Re: Feedback thread for self-marked exams
« Reply #15 on: October 27, 2019, 03:09:51 pm »
+1
This is my 2017 vcaa exam. I put red question marks next to the questions that I don't know if i should receive marks or not. I also took into consideration of writing in the box too haha.

https://www.dropbox.com/s/g7l3w77981cermu/new%20doc%202019-10-27%2014.49.44-20191027145712.pdf?dl=0

PhoenixxFire

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Re: Feedback thread for self-marked exams
« Reply #16 on: October 28, 2019, 12:06:38 pm »
+3
This is my 2017 vcaa exam. I put red question marks next to the questions that I don't know if i should receive marks or not. I also took into consideration of writing in the box too haha.

https://www.dropbox.com/s/g7l3w77981cermu/new%20doc%202019-10-27%2014.49.44-20191027145712.pdf?dl=0
2d. You've explained why the signalling molecule might be present and concluded that its presence mean the caterpillars prefer mature leaves - the question is asking about the effect of the signalling molecule - and specifically the effect on the cells of the young leaves, which you haven't answered.

4a. The context for this question isn't really about whether the joey is exposed to pathogens - it's saying the pouch isn't sterile, ie. the pouch isn't free from pathogens.

4e. You're being too general in your answer - the ultimate goal would be to make an antibiotic out of them, but you don't actually need testing for that, you could just chuck them in a drug and hope for the best. You need testing to ensure that they're effective in humans (not a great answer given effectiveness has already been discussed) and to ensure they're safe for humans.

5b. Your answer is fine. It's a bit strange that this is worth 3 marks - given the suggested answers I'd expect it to be worth 2. Be careful how you word things though - you said "without genetic variation" - there will probably still be some variation. Given it is worth 3 marks, I'd probably add two consequences of limited genetic variation rather than just one, even though vcaa doesn't seem to have required that.

6b. Don't use MT as shorthand here, it's not a standard biology term. Other than that, your answer is fine (with the correction of "more closely related" instead of "more recent common ancestor").

8a. Your answer is fine.

8b. The parents consent isn't really relevant - whether or not they're consenting to it isn't an ethical issue, carrying it out if they weren't consenting could be though but there's no indication that they haven't agreed to it. Your second point is a social implication not an ethical one.

9a. Most of your answer is fine, but it's not specifically a DNA molecule, even in this context. That would be like saying "Circular rings of DNA (plasmids) are Dna molecules that transport genes..." - The part about it being DNA is irrelevant because you've already said it's DNA by calling it a plasmid. "circular rings of DNA are a means of transporting genes..." is what the statement is saying. Therefore "vector" is being used to mean "a means of transporting genes..."

9bi. You would've got 1 mark for this. The question specifically asks how they help to insert the gene so you need to say how getting complimentary sticky ends helps.

9bii. You need to include the other genes in this plasmid because otherwise you've just drawn a circle with the human gene - it doesn't show how the human gene fits into this plasmid. You do also need to include the BamH1 recognition sites, it was probably just a mistake that they're not on the vcaa suggested solutions.

9c. You probably would have gotten 2 marks for this - you needed to specify the antibiotic.

It's interesting that for this question vcaa has decided to assume that every plasmid has taken up the human gene - in reality some plasmids would have joined back together without including it and you'd have to separate out those ones - you'd probably do it by growing colonies of each and then putting a bit from each colony onto a plate containing tetracycline - the ones that died had incorporated the human gene and you'd use those and get rid of the colonies of the ones that hadn't died.

However, vcaa said in the stem of the question that "the scientists has carried out the steps required to make plasmids with the inserted human gene", so they're wanting you to assume that all of the plasmids have successfully taken up the human gene - so all you need to do is get rid of the bacteria that didn't take up a plasmid.

I hate this question because this was my exam and I screwed it up haha.

10a. You don't need the first line. You need to be more specific about the consequences of the burning on the land (eg reducing food availability).

10b. Your answers are mostly fine, just be careful about the difference between evidence and justification and that you don't repeat yourself.

11c. It does make the experiment more valid, but that's not specific enough.

11d. Your second point isn't relevant because the temperature is being recorded.

11ei. Your answer is correct.
2019: B. Environment and Sustainability/B. Science @ ANU
2020: Just Vibing
2021: B. Paramedicine/B. Nursing @ ACU Canberra

Guest1121

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Re: Feedback thread for self-marked exams
« Reply #17 on: October 28, 2019, 12:35:59 pm »
+2
Hi, could someone please check my marking of the vaca 2018 practice exam? This is my first post so hopefully I've done this right! I wrote down most of the VCAA answers however I wasn't sure how many marks to award myself for each question. So if someone could please tell me how many marks each one is worth that would be amazing! Thanks!

https://www.dropbox.com/s/fcfcsuixxmsrs9z/Scan%20Mietta%2010.pdf?dl=0

PhoenixxFire

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Re: Feedback thread for self-marked exams
« Reply #18 on: October 29, 2019, 11:49:49 am »
+3
Hi, could someone please check my marking of the vaca 2018 practice exam? This is my first post so hopefully I've done this right! I wrote down most of the VCAA answers however I wasn't sure how many marks to award myself for each question. So if someone could please tell me how many marks each one is worth that would be amazing! Thanks!

https://www.dropbox.com/s/fcfcsuixxmsrs9z/Scan%20Mietta%2010.pdf?dl=0
1a. For your second line, call it a ribosome, not rRNA (a ribosome is made up of both rRNA and protein). Also mRNA has codons not triplets - triplets are on DNA.
You can get rid of the last line entirely - there are other steps that happen after translation for tryptase to form. Replace it with something like "when the ribosome reaches a stop codon, translation ends and the polypeptide is released."

4c. Don't call the toxin a pathogen. A pathogen is a disease causing agent - this doesn't cause disease.

6b. You've just repeated information given in the stem of the question for this. Make sure you're actually providing new information.

7a. A gene being recessive isn't the only reason it wouldn't be present in the whole population. You should probably have worded this differently - eg. saying that individuals can carry a gene and pass it down to their offspring without that gene effecting their own phenotype.

8b. The bit about preventing the DNA production of folic acid is a bit confusing - you should have said that the lack of active folic acid reduces dna production which slows cell growth because cell growth requires dna production.

8c. You only need to include one of the answers (either not suitable with reason or maybe suitable with reason), not both. You don't need to explain when an autoimmune disease occurs - just need to say that it is autoimmune and therefore antibiotics wouldn't work because they only work on bacteria.

10c. Reduced genetic diversity may have been accepted but you'd probably have to be more specific. eg. reduced genetic diversity of rice due to this strain becoming prevalent. Even then, there isn't heaps of diversity to farmed rice anyway because it's undergone artificial selection.

11b. Time is part of the dependent variable so it's not controlled.

11d. The hypothesis is that the red algal balls will photosynthesis faster than the green ones - so results contradictory to this would refute the hypothesis, either the green balls photosynthesising faster or at equal rate to the red balls.

11e. It's a negative control (a positive control would be white light). It's not about being able to compare them - it's to make sure the results are valid (that the colour change is actually due to photosynthesis).

For the questions I haven't commented on, your own corrections are fine. Your marking is also fine for the most part (whether some of your answers were accepted may have depended on the examiner/you may have gotten the mark from one examiner but not both).
2019: B. Environment and Sustainability/B. Science @ ANU
2020: Just Vibing
2021: B. Paramedicine/B. Nursing @ ACU Canberra

plubbles

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Re: Feedback thread for self-marked exams
« Reply #19 on: October 29, 2019, 05:33:38 pm »
+1
It's me again!
Guess what, i'm still not improving.
I know what the questions were, but for some reason, I either didn't know how to answer them, left a thing or two out, misinterpreted the question....

I would take any advice you can give me. I am kind of desperate.
Thank you!
2018 NH VCAA exam
https://www.dropbox.com/s/y62b8pnvh4jxrd7/2018%20NH%20VCAA%20Exam.pdf?dl=0

Bri MT

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Re: Feedback thread for self-marked exams
« Reply #20 on: October 29, 2019, 06:34:53 pm »
+2
It's me again!
Guess what, i'm still not improving.
I know what the questions were, but for some reason, I either didn't know how to answer them, left a thing or two out, misinterpreted the question....

I would take any advice you can give me. I am kind of desperate.
Thank you!
2018 NH VCAA exam
https://www.dropbox.com/s/y62b8pnvh4jxrd7/2018%20NH%20VCAA%20Exam.pdf?dl=0

I don't have time to do detailed feedback as I'm heading off to a meeting but:
- There are times when you aren't giving yourself the marks because you didn't use the same words as VCAA but your answer is till valid
- Have you experimented with your timing strategy? I found that getting that down helped me make less silly errors.


Question 8e. Look at the order of speciation. Based on this, we do not expect that the most recent common ancestor for each of the islands was canopy dwelling. Additionally, we do not expect there to have been significant gene flow between the island populations. This suggests that on each of the four islands characteristics suitable for living in a canopy environment evolved separately.

Remember that controls act as baselines against which the impact of the IV may be compared

Good luck!

Guest1121

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Re: Feedback thread for self-marked exams
« Reply #21 on: October 30, 2019, 07:12:56 pm »
0
thank you so much!



1a. For your second line, call it a ribosome, not rRNA (a ribosome is made up of both rRNA and protein). Also mRNA has codons not triplets - triplets are on DNA.
You can get rid of the last line entirely - there are other steps that happen after translation for tryptase to form. Replace it with something like "when the ribosome reaches a stop codon, translation ends and the polypeptide is released."

4c. Don't call the toxin a pathogen. A pathogen is a disease causing agent - this doesn't cause disease.

6b. You've just repeated information given in the stem of the question for this. Make sure you're actually providing new information.

7a. A gene being recessive isn't the only reason it wouldn't be present in the whole population. You should probably have worded this differently - eg. saying that individuals can carry a gene and pass it down to their offspring without that gene effecting their own phenotype.

8b. The bit about preventing the DNA production of folic acid is a bit confusing - you should have said that the lack of active folic acid reduces dna production which slows cell growth because cell growth requires dna production.

8c. You only need to include one of the answers (either not suitable with reason or maybe suitable with reason), not both. You don't need to explain when an autoimmune disease occurs - just need to say that it is autoimmune and therefore antibiotics wouldn't work because they only work on bacteria.

10c. Reduced genetic diversity may have been accepted but you'd probably have to be more specific. eg. reduced genetic diversity of rice due to this strain becoming prevalent. Even then, there isn't heaps of diversity to farmed rice anyway because it's undergone artificial selection.

11b. Time is part of the dependent variable so it's not controlled.

11d. The hypothesis is that the red algal balls will photosynthesis faster than the green ones - so results contradictory to this would refute the hypothesis, either the green balls photosynthesising faster or at equal rate to the red balls.

11e. It's a negative control (a positive control would be white light). It's not about being able to compare them - it's to make sure the results are valid (that the colour change is actually due to photosynthesis).

For the questions I haven't commented on, your own corrections are fine. Your marking is also fine for the most part (whether some of your answers were accepted may have depended on the examiner/you may have gotten the mark from one examiner but not both).