AQA BIOL5 Biology Unit 5 Exam - 22nd June 2011

Hey can anyone answer this question for me?
The Nelson Thornes textbook states on P143 that when organisms display kinesis, the more unpleasant the stimulus the more rapidly they move and the more rapidly they change direction. However in the CGP guide, it says that the more unpleasant the stimulus the more rapidly they move and the slower they change direction. They contradict! So which is correct?

I feel more included to trust the endorsed textbook, however the CGP book seems to make more logical sense. So according to CGP: in nice conditions they change direction a lot, so essentially they stay in the ideal area, and in horrible conditions they move in a straight line, so they would leave the nasty area quicker.

And the textbook reckons when in a nice place they dont change direction much, and in unpleasant areas they change direction more rapidly. Hmmm.

Please help?

that is incorrect. Klinokinesis - random movement in which rate is related to stimulus intensity
woodlice move more in pleasant environments. if they change direction less, they move in straight line so they will move out the area.

PCR involves a reaction mixture of DNA polymerase, free DNA nucleotides, primers and the DNA strand to be copied.

1. Heat reaction mixture to 95 degrees to break the hydrogen bonds between bases and so to uncoil the DNA strand.

2. Mixture cooled to 65 degrees. Primers; each with a complementary base sequence to the start of each strand, anneal to each polynucleotide strand.

3. Mixture heated to 72 degrees so DNA polymerase can work. DNA polymerase lines up free DNA nucletides on each strand and hydrogen bonds form between bases due to specfic base pairing.

4. Two new copies of DNA fragment formed, one cycle PCR complete

5. Each cycle double the amount of DNA strands,

PCR is in vitro cloning, cloning of a fragment of DNA outside of a living organims, whereas DNA replication happens inside a living organism: so in vivo cloning. DNA helicase is required for DNA replication, whereas for PCR it is not. Finally, DNA replication involves the whole of DNA being replicated, whereas PCR involves just a fragment.

I hate genetic engineering. PCR, Restriction Endonucleases and Reverse Transcriptase are the only bits I understand

The Nelson Thornes book has two pages on cystic fibrosis, but there is no mention of it in the specification. Do we even need to learn it?

We've been taught it the other way round, that the more unpleasant the surroundings are the more rapidly they move and more times they change directions. Still, I suspect that if there is a kinesis question in the paper it'll be obvious which case it is as it's a perfect one to use 'in context'.

I cannot get motivated for this exam! It's awful.

And I can't get my head around siRNA. I read it, I write it down, I do questions on it, but it's still not sticking.

I cannot get motivated for this exam! It's awful.

And I can't get my head around siRNA. I read it, I write it down, I do questions on it, but it's still not sticking.

Hey what part of it dont you get? Its one of the things that I didn't get initially but do understand now as part of the genetics sections so I'll try to help out

My book says cool it to 55C... :/

I suppose I don't really understand its applications, and where the associated proteins come from. I think I could explain how it works, but I'd be thrown off from a question if it didn't ask about siRNA directly.

If you know the process you will be fine I think. I don't think we have to know too much about where the associated proteins come from, my tb doesnt mention that (the NT one).

I think the main point apart from the process you have to know is that siRNA prevents mRNA from being translated, so no polypeptide will be formed, and therefore the gene is not expressed.

The NT book says its potential uses could be to use siRNA to block certain genes from being expressed which could be used to prevent genetic diseases.

Also it can be used to identify the role of genes. For example if an siRNA modeluce is added to cells, the effects of this can be observed and it can be determined what the role of the gene is.

I hope this helped , sorry if it didn't.

I think it is that the anatoxin is going to bind to the receptors. This will result an action potential being generated as sodium ions diffuse in. However, you know acetylcholinesterase breaks down acetylcholine which allows the action potential to stop, well the anatoxin cannot be broken down by acetylcholinesterase and so anatoxin is producing tears but it is causing excessive production as it is always producing an action potential which stimulates the production of tears. As the anatoxin cannot be broken down you are still getting action potentials therefore lots of tears.
Also correct me if i am wrong but an action potential doesn't just have to happen at a muscle right? so the action potential can be stimulated somewhere to do with tears??

I don't know if it's right, but that's what i would guess!

did anyone do the bio4 paper i heard that there wasent alot of hsw in the paper is this true
i hope there isnt alot of hsw in the bio5 paper

Yes, not much HSW at all for once! There's always one big HSW question in this unit, according to my biology teacher, question 10, the one before the essay.

If you know the process you will be fine I think. I don't think we have to know too much about where the associated proteins come from, my tb doesnt mention that (the NT one).

I think the main point apart from the process you have to know is that siRNA prevents mRNA from being translated, so no polypeptide will be formed, and therefore the gene is not expressed.

The NT book says its potential uses could be to use siRNA to block certain genes from being expressed which could be used to prevent genetic diseases.

Also it can be used to identify the role of genes. For example if an siRNA modeluce is added to cells, the effects of this can be observed and it can be determined what the role of the gene is.

I hope this helped , sorry if it didn't.