VCE Biology Question Thread

[purplegiraffe]

Is helicase involved in transcription, or just RNA polymerase? I'm hearing so many different things :/

For VCE's sake, Helicase is to unwind DNA in DNA replication.
You don't need to mention what unwinds DNA in transcription, just the fact that it does unwind.

source: Biology teacher is an exam assessor and she will not stop talking about this

[esthertham58]

Is it necessary to know about DNA profiling. Haven't seen much question on it though.

[geminii]

remember the processes like annealing, extending etc. (is denaturing one of them? think so) and some of the temps of each stage, and some potential uses of it (crime scene amplification etc.) gl!

You need to know the exact steps of how it works, and apply it to the situation given.

The steps in paragraph form are:

DNA fragments would be heated up to around 90-95°C to denature them into single-stranded fragments. The DNA is then cooled to 55°C and free DNA nucleotides and DNA primers are added to allow synthesis of the strand. This is then heated up to 72°C and taq polymerase is added, allowing the new strands to be synthesised as double-stranded segments. This process is then repeated millions of times, allowing millions of copies to be produced from the original DNA strand.

It appears a lot on exams so it's useful to know its application.

THANK YOU so much this helps a lot! But how is this different to DNA hybridisation? Isn't that the same thing?

[AhNeon]

How do bottlenecks and the founder effects lead to a decrease in genetic diversity
Does the decrease happen as there is the individuals left arent Representative of the original, or is it that the now smaller number cause chance events to have a bigger affect on gene pool-or both?

[plsbegentle]

Is it necessary to know about DNA profiling. Haven't seen much question on it though.

yes, the questions are really easy tbh. Have a look at the short answer of the 2014 exam. .

[esthertham58]

can someone give me some insight on reverse transcriptase. Thank you

[Springyboy]

THANK YOU so much this helps a lot! But how is this different to DNA hybridisation? Isn't that the same thing?

DNA Hybridisation is only used for evolutionary purposes, and compares the melting point of joined DNA sequences, that are only partially joined due to the two species being copied not being identical. Unlike PCR, hybridisation isn't making millions of copies, you are only trying to join two different species DNA samples to identify whether they are similar or not.

[guest123]

can someone give me some insight on reverse transcriptase. Thank you

Basically it is used to make complementary DNA which is DNA that is made from RNA and it doesn;t contain introns which makes it easier when undergoing transcription

[plsbegentle]

How do bottlenecks and the founder effects lead to a decrease in genetic diversity
Does the decrease happen as there is the individuals left arent Representative of the original, or is it that the now smaller number cause chance events to have a bigger affect on gene pool-or both?

yes, for the founder effect. The colonised poulation is an unrepresentative of the original population. For example, lets say you have 100 rabbits, with alleles of AA,Aa and aa. 10 of those rabbits leave and colonise in a new island (hypothetically speaking here). That 10 will almost certainly not be representative of the 100 population. And lets say those 10 rabbits have the alleles aa, you've lost all ur AAs and all ur Aa. So you've lost genetic diversity.

Bottleneck is the same concept, where there is a reduction in size of a population due a chance event, thus reducing the allele frequency.

[guest123]

can someone give me some insight on reverse transcriptase. Thank you

Basically it is used to make complementary DNA which is DNA that is made from RNA and it doesn;t contain introns which makes it easier when undergoing transcription

[purplegiraffe]

Wait, is this the actual cover page for the exam? Even though it says sample??

bump

[plsbegentle]

bump

can confirm, its legit!

[purplegiraffe]

can confirm, its legit!

omg only 35 pages?! maybe they're not going to have as many pictures

[The Usual Student]

omg only 35 pages?! maybe they're not going to have as many pictures

praying for a lot more 4-5 markers! There is 11 questions so
70/11 aprox 7 marks per question.

[HasibA]

omg only 35 pages?! maybe they're not going to have as many pictures

hopefully less pictures, and huge paragraphs of stimulus material to read hehe! after doing psych today, i really do think the number of pages + no of questions influences slightly what the exam asks.
eg psych was shorter ish, and had more shorter marker questions, with a 'unique' section c [all in my opinion of course hehe]
[sorry if its been double posted, really slow internet tonight]