5)
a) Gene flow refers to the exchange of alleles between different populations of the same species. It is unlikely to occur between these populations, due to the extent of the geographical separation between them and this species’ propensity not to stray far from the extents of its population.
b) The rufous bristlebird is at risk of extinction because its small population provides for very little genetic variation. This means that if there is a significant shift in the environment in which these populations lie, there may not be members of the population with the requisite traits to withstand the change.
6)
a) DNA fragments from two separate species are mixed and subsequently heated to separate the strands. They are then cooled, with the strands allowed to anneal to each other. Once again, the strands are heated and the temperature at which the DNA denatures is noted. This temperature is termed the melting temperature and is used in the determination of species’ relatedness.
b) Melting temperature correlates with the degree of relatedness between species, as higher temperatures imply a higher degree of sequence similarity of the DNA samples. Species that are more closely related are likely to have evolved from more proximate ancestors than those less closely related.
7)
a) Narrow waist. Large hip, knee and ankle joints. [This question will be controversial. Traditionally, the delineation between Australopithecus and Homo has been based on two things: tool-making and evidence of so-called competent bipedalism. There is no skeletal evidence of tool-making. I have provided evidence of “competent” bipedalism; however, expecting a VCE student to know these is fairly unreasonable. There is also the fact that there are not really a set of internationally accepted criteria about how to delineate these genera. Cranial capacity should not be referred to in this answer; early Homo species had small brains].
b) If H.naledi had arisen 900K years ago, it would have done so at a point at which H.erectus already existed. Given the striking similarities between H.erectus and humans, as well as the abundance of evidence that humans evolved from them, this would make it difficult to make a case for H.naledi as being a step between Australopithecus and humans, because it would by necessity invalidate the case for H.erectus.
a) A genetic screening programme allows for early diagnosis and thus early intervention for babies with genetic diseases, in the hope of securing a better clinical outcome for these infants.
b) Privacy: babies’ genetic data is, by necessity, collected and stored as part of the programme. Parents: may be reluctant to conceive again due to risk of disease.
9)
a) A means of transferring genetic material from one species to another.
b)
i) Restriction enzymes cut plasmids, thus revealing sticky ends at either end of the open plasmid. They are also used to prepare a segment of DNA for insertion, which will have sticky ends complementary to those of the plasmid. This allows for annealing and subsequent ligation of the inserted DNA and the plasmid.
ii) The human gene should be within the tcl gene. The rest of the diagram should be as above.
c) All of the bacteria are spread onto a petri dish enriched with ampicillin. Those bacteria that have taken up the plasmid will gain an ampicillin resistance gene (amp) and, as such, will be able to grow on the petri dish. Those bacteria that failed to take up the plasmid will be eliminated by the ampicillin; thus all bacteria growing on the dish will have the plasmid.
10)
a) The rapid extinction model proposes that many species became extinct in a short space of time, suggesting that a critical event or a series of critical events precipitated this extinction event. Two such references are made in the text. Evidence that the extinction happened soon after humans arrived in Australia provides a potential example of the kind of major change needed to precipitate an extinction. Another possibility referred to in the text is a rapid change in climate, which may have precipitated the extinction event.
b) Table in pdf answers.
Home
Help
Search
Login
Topic: VCE Biology Exam Discussion and Solutions (Read 100664 times)