AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

pH, temperature and water potential are three things that are controlled carefully by the body.

Does pressure count as something the body needs to control? (homeostasis).

yeah ive always wondered that.. thought it was about the examiners interpretation, like not right but not wrong so if the examiner think from the rest of what you have said that it was right then they can give.. not sure though

and how science works questions are the ones i like

Phew, thanks! Man this stuff can get confusing!



Thanks, my problem wasn't with what a DNA probe is, but with where they get the DNA probes they add to the single stranded DNA fragments in genetic fingerprinting.

Can anyone tell me what 'neutral' means on mark schemes? I've always wondered. Really dreading this essay and how science works questions tomorrow -.-

In genetic fingerprinting, it is a generic man made DNA fragment that attaches to core sequences.

There are two types of DNA probes, one that is complementary to a specific region/gene. This is used for identifying a mutated gene.
The one you are referring to is the one used in southern blotting/genetic finger printing. This is a generic man made DNA probe that annuals to core sequences in the DNA.

describe the use of hormones in humans ESSAY POINTS ? WHAT WOULD YOU WRITE

I got

1) the oestrous cycle
2) insulin & islet of langeran
3) if you can t prod a hormone - dibeites 1 ( breif about type 2)
4) Second mesenger model ( adrenaline)
5)Effect of hormones - (wide spred ect) + where it happens ie blood
6)differances between hormonal and nervius systme

what else i mean i couldnt think of any thing from other units ?

ohhhhh god i need to read up a bit then aha

There you go, took me a while to find it but it's really useful! Good luck tomorrow!

So which part of what I said was right, the first part or second part

And if it's neither then can you explain please?

They are essentially the same, it's just the second anneals to a less specific sequence. Where as in locating genes, the DNA probe is highly specific as it is identifying one gene.

send me the post, I've lost it

First thing:

Ok so during genetic fingerprinting, after they have separated the strands and transferred the single stranded DNA fragments onto a nylon membrane they add DNA probes to it.

My question: Where are these probes taken from? Is it from the person or animal the extracted sample is being tested against? If so then does the subsequent number of bands correspond to the chance it was the person or animal's DNA? Because I'm not really sure what the book is saying..

Second thing:


So what you're saying is the DNA probes will be the same every time, but the number of bands will change because people have different core sequences therefore the DNA probes will bind to different numbers of base sequences?

So is this pattern of bands then compared to the number of bands that the same DNA probes produced when annealed to the single stranded DNA of the person/animal you are comparing the extracted sample with?

Can anyone tell me what 'neutral' means on mark schemes? I've always wondered. Really dreading this essay and how science works questions tomorrow -.-