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.