After the EXAM (feedback)

[NE2000]

Question 6a)
"Scientists select a particular restriction enzyme from an available range, explain the reason for their choice."
I had no idea about this one , kind of had a wild guess.

Because they needed one that recognized sequences that were common in both individual 1 and 2?

I said something along the lines of they needed restriction enzymes that would cut differently for the different alleles so you could carry out an RFLP analysis (remember you need polymorphism in the restriction fragment lengths) but I worded it awfully, possibly worst wording I've ever put for an answer...why did I pick bio when I'm better at maths I do not know

[Ekky]

what was the ans to the " what appropriate method would be able to date the frogs?"

I said molecular clock using an amino acid like beta haemoglobin with a steady rate of mutation

I said DNA-DNA Hybridisation

[lacoste]

who hates this EXAM ??

if so we should have a thread like the connex thread!!

[susien7]

b

what was the ans to the " what appropriate method would be able to date the frogs?"

I said molecular clock using an amino acid like beta haemoglobin with a steady rate of mutation

I said DNA-DNA Hybridisation

but i thought that dna hybridisation would give an indication of how closely related they are. but wouldnt give like a time estimate? coz dna's mutation rate isnt as blah blah and such i dunno

[JL_91]

^ The greater the difference in number of base pairs between the two species, the longer they have been diverged for, i.e. evolving separately.

[Ekky]

^ The greater the difference in number of base pairs between the two species, the longer they have been diverged for, i.e. evolving separately.

That was my reasoning

[susien7]

but it asked like a date that they diverged or whatever
seeing as tho mdna has a known mutation rate, then it would be able to determine a date..

[bucket]

(what did people say caused their isolation? I said the habitat changes etc. etc.)

I wrote that it was just the different climates which acted as a physical barrier as they would present different selection pressures.

and for the Neanderthal vs. Homo sapiens I talked about possible gamete mortality;

I wrote exactly that.

Then the last question, I need to look at that again. I talked a bit about finding fossils of H. sapiens nearby but it wasn't until after the exam that I felt that I could have actually made that answer work. A lot of people I know talked about mtDNA but I thought they meant fossil evidence.

I thought fossil evidence too, for a new smaller skulled species I just wrote that the fact the skull was small suggested this, for the other one, the mutation, I wrote that Homo sapiens were alive in the same time period so it is possible that there was a mutation.

but it asked like a date that they diverged or whatever
seeing as tho mdna has a known mutation rate, then it would be able to determine a date..

This is what I was thinking when I answered that question.

[JL_91]

About the frogs - it was just asking how they can 'roughly estimate a date', like not a SPECIFIC date. Just a rough timeframe. It's nearly impossible to determine a precise date.

[toomoo]

When do the awnsers get put on the vcaa wedsite?

Cheers

[susien7]

About the frogs - it was just asking how they can 'roughly estimate a date', like not a SPECIFIC date. Just a rough timeframe. It's nearly impossible to determine a precise date.

yeah and mt dna would give you a closer rough estimate of the date, then dna hybridisation coz they don't know the mutation rate and all that crossing over business.

[NE2000]

About the frogs - it was just asking how they can 'roughly estimate a date', like not a SPECIFIC date. Just a rough timeframe. It's nearly impossible to determine a precise date.

Yes

My reasoning tho was that DNA-DNA hybridisation gives you a measure of how related they are but I haven't seen NoB directly use the results like a molecular clock.

[bucket]

About the frogs - it was just asking how they can 'roughly estimate a date', like not a SPECIFIC date. Just a rough timeframe. It's nearly impossible to determine a precise date.

yeah and mt dna would give you a closer rough estimate of the date, then dna hybridisation coz they don't know the mutation rate and all that crossing over business.

Yeah exactly, the mutation of nuclear DNA is more random.

[NE2000]

That said, I wasn't sure whether the beta chain of haemoglobin would change significantly in that time. Hopefully they accept it, mtDNA would have been better I guess.

[bucket]

Mmm, unlike the other geniuses in this forum, I thought that the exam was hard. I am pretty sure I've lost more than 5 marks :s. There goes my dreams of an A+