VCE Biology Question Thread

[AllG_]

Omg exam's in less than a week!!  :S

Anyway, apart from more co-ordinated hunting, how is speech a survival advantage? I'm quite hesitant to use the 'more coorindated hunting' response now after the assessment report for VCAA 2007 Q24 for MC stated that "Organised hunting (option D) could be achieved using visual cues and gestures. Many animals, such as dogs, hunt prey in a coordinated fashion without articulate speech."

Also, what would the survival advantage of having a larger brain in general? Would one of them be that it allows for more complex thinking, hence more able to develop stone tools, clothes etc.?
Thankss

[DJA]

Survival advantage of speech = allows for sophisticated learning and teaching of survival techniques to next generation of offspring

Survival advantage of a larger brain = ability to have more complex thoughts, better decision making, higher intelligence allows for more complex actions such as envisaging the possible outcome of a future event - an ability only humans can perform.

[DJA]

Why is mtDNA useful for determining evolutionary relationships?

[nhmn0301]

Why is mtDNA useful for determining evolutionary relationships?

mtDNA mutate fairly quickly do can only be used for recently diverged species, however, it is pretty well conserved between mother and her offspring.

[katiesaliba]

Why is mtDNA useful for determining evolutionary relationships?

-no recombination
-maternal lineage
-fast mutations in non-coding regions
-slow mutations in coding regions
-more abundant than nuclear DNA

[Reus]

Why is mtDNA useful for determining evolutionary relationships?

It's useful because fast mutations occur in non-coding regions (which aren't expressed) and can be used as molecular clock.

However mainly mtDNA is more useful than nuclear DNA because it is maternally passed down to offspring meaning it is not subjected to recombination. This means the mutations that have occurred between organisms that share a common ancestor will be sequenced in a lineage from evolutionary processes and nothing else. Then of course the number of nucleotide differences in mtDNA will indicate the time between the similarities diverging (as a larger number of difference b/w organisms highlights a longer time elapse).

[DJA]

Thanks people

[katiesaliba]

So, do all protein hormones consist of a quaternary structure? Because a QAT exam question implied that they do.

[DJA]

So, do all protein hormones consist of a quaternary structure? Because a QAT exam question implied that they do.

No. You can have protein hormones that are essentially amino acid derivatives which would definitely not have a quaternary structure:

Amino Acid Derivatives (e.g thyroxine)
•   Small
•   Water soluble/Hydrophilic/Lipophobic, cannot readily pass through cell membranes
•   Relies on cell surface receptors on target cells and hence does not actually pass into the cell itself
•   Travels free in bloodstream
•   Stored in secretory vesicles and travels out of endocrine cell via exocytosis
•   Relatively short lifespan
•   Synthesised in the rER (amino acid)

[Reus]

What diagrams do you guys think they might ask us to draw? Just list them!

[DJA]

These are my guesses

->Fill in a negative feedback loop of glucose homeostasis (info will be provided in stem)
->A full on dihybrid cross with 2 traits (with like 2 hetereozygyotes at both gene loci) - VCAA study design says this is possible - hasn't been done yet but possible.
->Draw a pedigree - for a trait (X linked or autosomal)
->Draw steps of meiosis for gamete creation (sperm I'm guessing)

[Reus]

These are my guesses

->Fill in a negative feedback loop of glucose homeostasis (info will be provided in stem)
->A full on dihybrid cross with 2 traits (with like 2 hetereozygyotes at both gene loci) - VCAA study design says this is possible - hasn't been done yet but possible.
->Draw a pedigree - for a trait (X linked or autosomal)
->Draw steps of meiosis for gamete creation (sperm I'm guessing)

That I haven't seen yet... hmmm thanks for that!

[Rishi97]

In PCR, why is heat used to separate the strands instead of DNA helicase?

[DJA]

That I haven't seen yet... hmmm thanks for that!

Do you have any other guesses? 

[DJA]

In PCR, why is heat used to separate the strands instead of DNA helicase?

I think that's just the traditional way of doing it (as in heat for PCR). Sorry I don't have a better answer 

Note there ARE variations of PCR that use helicase instead. See here: http://en.wikipedia.org/wiki/Helicase-dependent_amplification