VCE Biology Exam - 01/11/19 - Discussion/Questions/Solutions

[3086]

What study score would be equivalent to around 86-87% in SACS and exam?

You're looking at around a 41 especially since the exam's A+ cut off will be higher than last year's. Last year you would have gotten around a 42 and maybe even a 43.

[Erutepa]

what if you wrote time for the limitation question and said you could use a digital timer which could be more accurate than humans stopping the stop watch?

Limitations are disadvantages of experimental desgin that impair its ability to identify the effect of the IV on the DV. For this experiment, a limitation would be anything that impairs our ability to say that increase temperature decreases the time taken for neautralisation to occur. An inaccurate timing method could be a limitation as if the timing method gave inconsitant times the experiment's ability to accurately test the relationship betwen the IV and the DV is flawed. I would however be reluctant to use this as a limitation since I don't think using an automatic timer (I assume this is what you mean by digital) is able to be applied to this experiment. However if you justified it properly, you might be awarded the mark, depending on how strictly thay mark the question.

[3086]

Would it be accurate to say this: Nuclear DNA is made with crossing over from meiosis which therefore suggests that it contains genetic information from the mother and father of the organism. According to this theory, scientists prefered nuclear DNA because it can show whether the young girl (referred to in the article) in fact was the product of interbreeding between Denisovans and Neantherals thereby providing information into the history of Denisovans which mtDNA cannot as it does not have recombinant DNA from the parents.

[Bri MT]

Would it be accurate to say this: Nuclear DNA is made with crossing over from meiosis which therefore suggests that it contains genetic information from the mother and father of the organism. According to this theory, scientists prefered nuclear DNA because it can show whether the young girl (referred to in the article) in fact was the product of interbreeding between Denisovans and Neantherals thereby providing information into the history of Denisovans which mtDNA cannot as it does not have recombinant DNA from the parents.

Haven't read the question but:

Crossing over in meiosis doesn't cause the DNA to be from two parents but it does mean that DNA from 2 parents can be found on the one chromosome.

[3086]

Haven't read the question but:

Crossing over in meiosis doesn't cause the DNA to be from two parents but it does mean that DNA from 2 parents can be found on the one chromosome.

Regardless, it still implies that interbreeding must have occurred

[Bri MT]

Regardless, it still implies that interbreeding must have occurred

If you have DNA from multiple sources present in the one organism then yes that does indicate that interbreeding has occurred. However, my point was that this "Nuclear DNA is made with crossing over from meiosis which therefore suggests that it contains genetic information from the mother and father of the organism" could potentially lead you to have marks deducted as crossing over doesn't have the role you are suggested it does. Your response suggests that you don't (or didn't) understand the role of crossing over compared to recombination, and instead recognised "crossing over" as a difference between nuclear and mtDNA (without knowing what it is) and thus included it in your answer even when not relevant to the situation.

I have responded in the way I did because your question was "would it be accurate to say this"

You're not expected to have the same level of understanding of crossing over & recombination as I was in my study design so maybe they'll overlook it.

[Highway_end]

What study score should I expect with unit 3 sacs at 85%, unit 4 sacs at 81% and exam at 80%ish ? assuming no scaling of sacs

[Sine]

What study score should I expect with unit 3 sacs at 85%, unit 4 sacs at 81% and exam at 80%ish ? assuming no scaling of sacs

Around a 40 or high 30s with no scaling of sacs imo

[Marianakans]

For question 6di, I recall that it was a substitution in the 12th nucleotide of the mRNA codon, and that they both coded for leucine regardless... correct me if I'm wrong. And for question 11e, would it be appropriate to state that it was difficult to determine the exact time at which the pH became neutral, and hence using a more sensitive pH probe is required.

Thanks

[Erutepa]

For question 6di, I recall that it was a substitution in the 12th nucleotide of the mRNA codon, and that they both coded for leucine regardless... correct me if I'm wrong. And for question 11e, would it be appropriate to state that it was difficult to determine the exact time at which the pH became neutral, and hence using a more sensitive pH probe is required.

Thanks

6di actually stated a that the twentieth nucleotide changed to uracil. This would change the amino acid that the codon coded for from glycine to valine.

I personally would have said that the method to determine the pH change may/couldhave been innacurate (since its not stated that it actually was), in which case using a digital pH probe would give more accurate pH readings and thus improve the the accuracy of the experimental design. However, I think you would still get the mark for this.

[Marianakans]

Also, for question 11 did you have to exclusively state that the measurements were too low or could you just state them and then explain the errors... and if I'm rank 1 and got around 88% on exam, what study score should I get??

[darkz]

Also, for question 11 did you have to exclusively state that the measurements were too low or could you just state them and then explain the errors... and if I'm rank 1 and got around 88% on exam, what study score should I get??

Assuming 100% SACs and 2018 distribution, I'd say around 45-47

[PhoenixxFire]

Also, for question 11 did you have to exclusively state that the measurements were too low or could you just state them and then explain the errors.

Is this for 11c? The question just asks you to identify the errors and give two examples of sources of errors, so you should be fine to just name them without justifying why they were the ones with errors.

[tdowler100]

With around 88% sacs and 80/75% on the exam what study score could I get (before scaling)?

[PhoenixxFire]

With around 88% sacs and 80/75% on the exam what study score could I get (before scaling)?

High 30s, maybe 40.