Biology Practice Exam Discussion

[Biology24123]

Sounds about right. If you're doing 2010 VCAA or earlier...

I vaguely remember someone getting 67.5 and 67 in 2010 and ended up with a 47. I myself got 68.5 and 72 and ended up with 50 + Premiers - if you wanted to gauge how well you are doing in your past VCAAs.

I thought you would need higher than 67 to get a 47. What about the combined exams 97+/110?

[thushan]

Hahah back then the exams were harder (A+ cuts were about 75-83%).

[Sine]

What do you guys think about exam score--->Study score for VCAA 2012

The A+ cut-offs were ridiculous, Unit 3 [64.5/75] Unit 4{65/75], I got around 70/75 for Unit 3 and 70-72/75 for Unit 4?

[warya]

What do you guys think about exam score--->Study score for VCAA 2012

The A+ cut-offs were ridiculous, Unit 3 [64.5/75] Unit 4{65/75], I got around 70/75 for Unit 3 and 70-72/75 for Unit 4?

Probs 50...no point thinking about that stuff though, no one can give you a definitive answer

[Biology24123]

What do you guys think about exam score--->Study score for VCAA 2012

The A+ cut-offs were ridiculous, Unit 3 [64.5/75] Unit 4{65/75], I got around 70/75 for Unit 3 and 70-72/75 for Unit 4?

Probably 47

[Biology24123]

Probs 50...no point thinking about that stuff though, no one can give you a definitive answer

Unit 3 there are at least 5 marks not on the new study design

[Jay.C]

Hey, can someone please give me an example of how they would answer this question: how does dna profiling let us identify individuals?

Thanks 

[foodieisanunderstatement]

How did you guys go with VCAA 2013? And does anyone know what you would need to get on it for 45 or over?

[Sine]

How did you guys go with VCAA 2013? And does anyone know what you would need to get on it for 45 or over?

you needed roughly 98-99/110 for a 45 with near to full scaling sac marks.


VCAA 2013
5(a) Question: What role do these autoantibodies play in causing the symptoms of an autoimmune disease? 1 mark

My Answer: Autoantibodies are specific to self-cells & work on self-cells by bind to them (opsinization) results in phagocytes engulfing and destroying self-material causing symptoms of an auto immune disease.

VCAA Answer: Autoantibodies attack self-cells and the destruction of this tissue leads to the symptoms of the disease.

5(b) Explain why the auto antibody test could be negative even though the genetic screen was positive. (My answer is totally different) 2 marks

My Answer: The teenager may be heterozygous at that gene loci & the trait may be autosomal recessive thus required two faulty alleles to express the phenotype to produce the auto antibodies, therefore did not produce auto antibodies.

VCAA Answer: The genetic screen indicates the potential to develop the disease and the absence of autoantibodies indicates that the disease has not yet been switched on.

8(c)(iii) Explain whether you would expect the same genotype and phenotypes in the offspring if the two genes had been linked. 1 mark

My Answer: No the phenotypes and genotypes would be different as some allelic pairs would more likely to be inherited together & some only occurring when crossing over occurs between the gene loci. The phenotype & genotypic ratio would be large: large (parental combinations) & small: small (recombinant combinations

VCAA Answer: Yes. The same genotypes and phenotypes are possible if crossing over/recombination occurred OR
 No. Only two types of genotypes and phenotypes are produced, or the majority are of two types.

10(a) What molecular information would the scientist obtain from sequencing RNA? 1 mark

My Answer: The sequence of amino acids exhibited in polypeptides produced by the virus in a host cell.

VCAA Answer: The sequence of nucleotides or bases could be determined.

IMO it was quite a good exam as it differentiated the state really well despite being relatively simple however 2014 exam was pretty much about who will not make stupid mistakes XD

Thanks in advance

[thushan]

VCAA 2013
5(a) Question: What role do these autoantibodies play in causing the symptoms of an autoimmune disease? 1 mark

My Answer: Autoantibodies are specific to self-cells & work on self-cells by bind to them (opsinization) results in phagocytes engulfing and destroying self-material causing symptoms of an auto immune disease.

VCAA Answer: Autoantibodies attack self-cells and the destruction of this tissue leads to the symptoms of the disease.

Mark: 0.5/1. Whilst you got the essentials here, my concern is your use of the word 'opsonisation'. This term describes a process whereby the binding of an antibody to an antigen makes it easier for a phagocyte to engulf the antigen. I'm not sure whether you used that term to describe the binding of antibodies to the antigen, or its true definition. I think one examiner will pay the mark whereas the other may not, so 0.5/1.

5(b) Explain why the auto antibody test could be negative even though the genetic screen was positive. (My answer is totally different) 2 marks

My Answer: The teenager may be heterozygous at that gene loci & the trait may be autosomal recessive thus required two faulty alleles to express the phenotype to produce the auto antibodies, therefore did not produce auto antibodies.

VCAA Answer: The genetic screen indicates the potential to develop the disease and the absence of autoantibodies indicates that the disease has not yet been switched on.

Mark: 0.5/1. I wasn't sure about this. For your level of knowledge at Year 12, it would have been perfectly reasonable to say what you did. If I were an examiner, I'd give you full marks. However, I'm anticipating that some examiners may give the mark, and others wouldn't.

8(c)(iii) Explain whether you would expect the same genotype and phenotypes in the offspring if the two genes had been linked. 1 mark

My Answer: No the phenotypes and genotypes would be different as some allelic pairs would more likely to be inherited together & some only occurring when crossing over occurs between the gene loci. The phenotype & genotypic ratio would be large: large (parental combinations) & small: small (recombinant combinations

VCAA Answer: Yes. The same genotypes and phenotypes are possible if crossing over/recombination occurred OR
 No. Only two types of genotypes and phenotypes are produced, or the majority are of two types.

Mark: 1/1. Careful though, when using terms like genotypic and phenotypic ratio, that you are clear in what you expect them to be. I nearly gave you 0.5 for this.

10(a) What molecular information would the scientist obtain from sequencing RNA? 1 mark

My Answer: The sequence of amino acids exhibited in polypeptides produced by the virus in a host cell.

VCAA Answer: The sequence of nucleotides or bases could be determined.

Mark: 0/1. Issue here is that from the RNA sequence alone, you cannot figure out which proteins the virus can make because you do not know which segments of RNA are actually used to produce protein.

Hope that helps! Sorry if I sounded mean

[vox nihili]

10(a) What molecular information would the scientist obtain from sequencing RNA? 1 mark

My Answer: The sequence of amino acids exhibited in polypeptides produced by the virus in a host cell.

VCAA Answer: The sequence of nucleotides or bases could be determined.

Mark: 0/1. Issue here is that from the RNA sequence alone, you cannot figure out which proteins the virus can make because you do not know which segments of RNA are actually used to produce protein.

Hope that helps! Sorry if I sounded mean

Just going to jump in on this one. I'm not sure whether VCAA would give you the marks for this one given your answer differs so substantially from theirs, but your answer is correct.
It is possible, indeed relatively easy in fact, to work out the sequence of amino acids in a protein by sequencing the RNA that codes for it. Well beyond the VCE course, but you can use bioinformatic tools to work out which parts of the RNA are coding for protein and which parts correspond to untranslated regions.

[Sine]

VCAA 2013
5(a) Question: What role do these autoantibodies play in causing the symptoms of an autoimmune disease? 1 mark

My Answer: Autoantibodies are specific to self-cells & work on self-cells by bind to them (opsinization) results in phagocytes engulfing and destroying self-material causing symptoms of an auto immune disease.

VCAA Answer: Autoantibodies attack self-cells and the destruction of this tissue leads to the symptoms of the disease.

Mark: 0.5/1. Whilst you got the essentials here, my concern is your use of the word 'opsonisation'. This term describes a process whereby the binding of an antibody to an antigen makes it easier for a phagocyte to engulf the antigen. I'm not sure whether you used that term to describe the binding of antibodies to the antigen, or its true definition. I think one examiner will pay the mark whereas the other may not, so 0.5/1.

5(b) Explain why the auto antibody test could be negative even though the genetic screen was positive. (My answer is totally different) 2 marks

My Answer: The teenager may be heterozygous at that gene loci & the trait may be autosomal recessive thus required two faulty alleles to express the phenotype to produce the auto antibodies, therefore did not produce auto antibodies.

VCAA Answer: The genetic screen indicates the potential to develop the disease and the absence of autoantibodies indicates that the disease has not yet been switched on.

Mark: 0.5/1. I wasn't sure about this. For your level of knowledge at Year 12, it would have been perfectly reasonable to say what you did. If I were an examiner, I'd give you full marks. However, I'm anticipating that some examiners may give the mark, and others wouldn't.

8(c)(iii) Explain whether you would expect the same genotype and phenotypes in the offspring if the two genes had been linked. 1 mark

My Answer: No the phenotypes and genotypes would be different as some allelic pairs would more likely to be inherited together & some only occurring when crossing over occurs between the gene loci. The phenotype & genotypic ratio would be large: large (parental combinations) & small: small (recombinant combinations

VCAA Answer: Yes. The same genotypes and phenotypes are possible if crossing over/recombination occurred OR
 No. Only two types of genotypes and phenotypes are produced, or the majority are of two types.

Mark: 1/1. Careful though, when using terms like genotypic and phenotypic ratio, that you are clear in what you expect them to be. I nearly gave you 0.5 for this.

10(a) What molecular information would the scientist obtain from sequencing RNA? 1 mark

My Answer: The sequence of amino acids exhibited in polypeptides produced by the virus in a host cell.

VCAA Answer: The sequence of nucleotides or bases could be determined.

Mark: 0/1. Issue here is that from the RNA sequence alone, you cannot figure out which proteins the virus can make because you do not know which segments of RNA are actually used to produce protein.

Hope that helps! Sorry if I sounded mean

Thanks for the help    greatly appreciated!, haha it's actually more of a confidence boost because usually I just mark my self wrong if my answer is not similar to the assessors report.

Just going to jump in on this one. I'm not sure whether VCAA would give you the marks for this one given your answer differs so substantially from theirs, but your answer is correct.
It is possible, indeed relatively easy in fact, to work out the sequence of amino acids in a protein by sequencing the RNA that codes for it. Well beyond the VCE course, but you can use bioinformatic tools to work out which parts of the RNA are coding for protein and which parts correspond to untranslated regions.

thanks, I have no idea why I didn't just say sequence of bases. I need to make sure to give the most obvious answer.

[vox nihili]

thanks, I have no idea why I didn't just say sequence of bases. I need to make sure to give the most obvious answer.

It's almost an insultingly obvious answer. I think I'd have gotten it "wrong" too.

[cosine]

For the attached:

- How do we know how many things to label on the diagram?
- You see how my arrows are mostly facing the north side of the page? Do we need to keep this organised and keep all arrows to one side of the diagram?
- Can the arrows go through the structures of the diagram? Like when i labelled DNA helicase the arrow went through the DNA, is this allowed?
- Do we need to show the nitrogenous bases or are the lines alright?

[cosine]

Also for the attached, you see for step 3, why is there an 'or'? I usually say after cooling down to 54 degrees, then primers are added and attach to the 3' ends of each single strand, and then DNA polymerase synthesises the DNA strands in the 5'-'3 direction. Is it necessary to say to increase temperature from 54 to 74?