AQA AS BIO Unit 2 OLD SPEC RESIT Tue 7th June (pm) 2016

I put almost the same but because it was talking about phylogenetic I said that the two species which had the same nucleotide sequence had a more recent common ancestor and the other had a more distant common ancestor?:/

I talked about DNA hybridisation and compare the separation temperature of the mixed one to that of a normal bacterium. Any significant deviations from the normal one(doesn't matter which one you use I suppose, if they were indeed identical that is) would mean that they are not identical bacteria.

Did anyone know what other conclusions scientists could make for that artery question? I had no idea.

What did you put for the species diversity one?

The one about making conclusions and then the one about what additional steps should be made?

I said that no definite conclusion can be made because both conclusions contradict each other.

For addition steps, I said repeat the investigation by another group to identify and reduce the effect of anomalies, share findings and use statistical tests to see if results are significant/due to chance?

I think someone has done an answer for this further back (sorry I cant remember!). I put something along the lines of 'bacteria in human faeces more likely to spread and infect other humans than bacteria in animal faeces as strains may be different'

I think it specified for humans?

I highly doubt that is right, all I did was waffle on for too long

How can you talk about Dna hybridisation when they are the same species


Posted from TSR Mobile

Remind me what the context was regarding the species diversity thing you are referring to? It's been a long day haha

How can you talk about Dna hybridisation when they are the same species


Posted from TSR Mobile

Something like another scientist calculated the index of diversity of the river with the sewage and obtained a high index of diversity, whilst the other person calculated a low species of diversity - how does this new index of diversity affect the conclusions made or something?



What did you put for that question?

I think I said compare the DNA base sequence.

Since the question said to identify if they're identical I said that the DNA base sequence would need to be identical for them to be of the same species or whatever it was.

Ah right. It asked us about how no conclusions can be drawn after the new set of results have been recorded by the 2nd scientist. I said the results obtained are not in agreement with each other and so no valid conclusion can be drawn as there is no way one can tell as to which scientist was right.

The follow-up question on a way in which they can find the species diversity was by both scientist agreeing on a method of investigation that they both think would provide valid and representative results and actually do it, do repeats if possible.

Not entirely sure if I'd hit the nail but oh well.


Do you agree on the DNA hybridisation thing?

I agree with the first question.

I mentioned about repeats for second one.

My first thought was DNA hybridisation but I don't know why I just said to compare the DNA base sequence for the same gene and if they're identical then they're of the same species - but I believe DNA hybridisation should be right.

I was fearing for that. I think you are right. I just talked about the two with the same nucleotide base sequence are more closely related than the one is to the two as its nucleotide base sequence is very different. :/ Well done though.

I'm pretty sure they will accept either response. I also spoke about the comparison of the sequence of bases. However they said describe ONE method and one was in bold, thereby meaning that there are a variety of methods to choose from. We should be fine.

Did it? Brilliant!

What did you write exactly?

My response is on your previous quote thingy.

My response was very similar to yours:

-Compare the sequence of their DNA bases
-The higher the percentage similarity in the order of the bases, then the bacteria are from the same species

I think I'll subtract a mark just in case from my response.

Thanks though you've helped a lot!