Can someone check whether I would be able to obtain any marks from these answers? All questions are from VCAA 2010 Unit 4
Q1(c)(ii) What is a key difference between a prokaryotic chromosome and a plasmid? 1 mark
My Answer: Prokaryotic chromosomes cannot be passed along between bacteria, plasmids can be passed from bacterium to bacterium.
VCAA answers: replicate independently of binary fission
can be used as vectors in genetic transformation.
Q3(c) Explain why the male is phenotypically normal in spite of carrying the translocation shown? 1 mark
My Answer: There is no loss of genetic material thus they can still synthesise appropriate proteins.
VCAA answer:The same genetic material is still present within the cell but in a different position.
Q3(e)(ii) Outline your reasoning (check exam Unit 4 2010) 1 mark
My answer: There are 4 possible permutation of chromosomes via independent assortment, only 1 way in which the normal chromosomes are on the same side. 1/2 chance of one normal chromosome being on one side & 1/2 chance of the other normal chromosome being on the same side i.e 1/2 x 1/2 = 1/4
VCAA answer: For each homologous pair of chromosomes there are two choices of lining up. There are therefore four possibilities, of
which one combination has both normal (untranslocated) chromosomes.
Q4(b) What would you expect to happen to the shell thickness of the northern blue mussels over time? Explain your reasoning? 2 marks
My answer: I would expect the thickness to remain relatively constant as those mussels are not being subjected to a change in environment or change in selection pressures.
VCAA answer: Either of:
no change in variation and due to crabs (selection pressure) not being present
variation occurs due to a different selection pressure or gene flow with the Southern population.
Q5(b) Why was the inactivation of one of the centromeres a significant step in human evolution? 2 marks
My answer: It ensured that human chromosome 2 was able to line up as homologous pair of chromosomes in meiosis to produce gametes.
VCAA answer: Both of:
the inactivation of one centromere enables meiosis/cell replication to occur
gametes are able to be produced.
Q(b)(ii) Outline one disadvantage of a plantation of marula trees grown through marcotting compared to a natural population of marula trees 1 mark
My answer: This decreases genetic variation subsequently they are more likely to go extinct in changes of environment & changes of selection pressures.
VCAA answer: The lack of variety means that for example, should a disease occur, the resistance would be the same and may lead to
extinction.
Thanks in advance!
1cii—maybe, though probably not. Within the bounds of the VCE course you are probably correct, but I would venture that it's not really a key difference.
3c—again, maybe. You've understood that there's no loss of material, but I'd guess that they'd probably want some sort of indication that you understood what a translocation is, which with your answer you haven't really demonstrated.
3eii—yep, all good
4b—maybe. If they've mentioned crabs in the detail of the question you should mention them too. It's not enough to give the theory, you do have to relate it to the problem that they've presented. In this case, they were testing whether or not you could apply concepts in evolution to this problem.
5b—yep, you've said what they've asked for just with more words.
bii—you probably would get the marks for this, though it does sound like you're floundering a bit. I think with this one you've struggled to express what you wanted to say, but you do seem to know what you're on about. For that reason, they would probably give you the marks, as you are essentially correct. Lack of variation leads to more likely extinction in a changing environment.
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