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AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

Reply 1840

mulac1

I wouldn't say thats off spec...

Reply 1841

samfreak

after the insulin gene is inserted into the bacterial plasmid and then tooken up bacteria and the transfored bacteria have been identified and cloned.....then what happens? do the bacteria produce insulin or is the insulin isolated and transplanted into a human?

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Reply 1842

master y

12

Original post by samfreak

after the insulin gene is inserted into the bacterial plasmid and then tooken up bacteria and the transfored bacteria have been identified and cloned.....then what happens? do the bacteria produce insulin or is the insulin isolated and transplanted into a human?

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bacteria secrete insulin, and you collect it

Reply 1843

F1's Finest

21

Original post by hollywils

Thanks!! Got a B in the mock so fingers crossed... Just hoping the essay question is a nice one!

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Just pos repped you, I don't know who negged you :s-smilie:

Reply 1844

F1's Finest

21

Original post by master y

bacteria secrete insulin, and you collect it

Yep, but it's good to say that it's 'extracted' from the bacteria, rather than collecting it. Sometimes with these fussy examiners and mark schemes, you gotta be on the safe side :yy:

Reply 1845

mulac1

What do people think will be the essay Q?

Reply 1846

F1's Finest

21

Original post by mulac1

What do people think will be the essay Q?

haha thankyou for the neg rep :smile:

Reply 1847

JenLivYoung

Why is gene tech so boring to learn when in real life it's quite exciting? *sigh*

Reply 1848

AtomicMan

13

Given up on trying to get an A* in Biology lol, will just settle for the A.

Reply 1849

omnom

guys i am at the end of my AS, thought i will get myself some BIOL4/BIOL5 resources ready for next year. i came across the synoptic essay book on amazon for about 10 pounds, i found the ebook for free on this link, it has 20 essays in it. good look guys. feel free to give me rep. here is the link : http://w1.qehs.net/files/docs/exam_resources/Year12/biology/biology_a2_sample_synoptic_essays.pdf

Reply 1850

guitardad

10

Original post by stoppy123

Questions!

Name the 3 factors that influence speed of neurone transmission (3)
State and explain the two types of summation (4)
Explain how siRNA could be use in medicine (2)
Briefly describe the steps in in-vitro cloning (5)
Give two ways in which the cell takes up a vector (2)
Briefly describe the reflex arc (2)
What is the role of acetylcholinerase? (2)

1) temperature, axon diameter, whether they're mylenated or not?
2) temporal summation - a lot of impulses reach a presynaptic neurone - (neurotransmitters released with each impulse) - a lot/enough nuerotransmitters released into synaptic cleft ~(due to high frequency of impulses in a period of time) and bind to the receptors on the postsynaptic membrane -action potential generated

spatial summation - many neurones release neurotransmitters to one postsynaptic neurone- only a small amount of neurotransmitters released at each neurone but together the amount of neurotransmitters can bind to the one post synaptic nuerone and generate an action potential.

3) using a plasmid vector - taken up by first making the bacteria cell permeable by placing it in cold calcuim chloride and then being taken up (normally heat shocked to take up recombinant dna plasmid)

or a bacteriophage (viral vector) - inserts its dna into bacterias dna

4) Dna strand, primers, free dna nucleotides, and dna polymerase required.
First heat up dna strand to 90 degrees so that the H-bonds between the dna strands break and so the two strands can be used at templates (exposes the base sequences). Then cool down to 50 deg and add primers - cooling to this temperature allows primers to anneal to the start of the target genes base sequence. The mixture is then heated up to 72 deg and DNA polymerase is added - dna polymerase aligns complementary dna nucleotides to the dna strand - using specific base pairings and joins nucleotides together forming a complementary stand of dna. Repeat.

5) A stimulus is detected - impulse is sent along a sensory neurone to the spinal chord - an impulse sent from spinal chord along a motor neurone to effector (e,g muscle) response carried out.

6) AChe breaks down Ach in the synaptic cleft, so it does not bind to cholinergic receptors and keep causing action potentials - also makes sure that when ACh is released from the presynaptic neurone that there is a a higher concentration at the presynaptic neurone so ACh can diffuse along the synaptic cleft to the postsynaptic nuerone and bind to cholinergic receptors ( ensures an impulse is unidirectional)

?

(edited 10 years ago)

Reply 1851

guitardad

10

Original post by master y

Is this ok? :s-smilie:

Please tell me if i have missed out ANY detail, no matter how small!! Or made any mistakes,..

you described in vivo cloning there I think

Reply 1852

kitkat95

3

Original post by Richyp22

Ok I think homeostasis may come up as an essay title, I'm just wondering if theres any other methods of homeostatsis that people can think of apart from-

- Blood pressure
- Temperature
- glucose
- Ph buffers
- Immune response(Possibly)
- Kidney ultrafilteration
?

Reckon there'd be any marks for mentioning respiration? Guess it's kinda just an extension from the blood pH point? It involves negative feedback because a change in blood gas composition is detected (mostly by chemoreceptors) and an impulse is sent to increase respiration rate and also to increase the force of contraction of the internal and external intercostal muscles to cause the tidal volume to increase. This will return blood gas composition to normal levels. Think this would be relevant or just going off topic?
Also, which pH buffers have you learnt about? The only one I can think of is hydrogen carbonate but I only know of that one because of chemistry :s-smilie:

(edited 10 years ago)

Reply 1853

DELETED ACCOUNT

15

Original post by AtomicMan

Given up on trying to get an A* in Biology lol, will just settle for the A.

There's no point in giving up now. You haven't even done the exam yet!!!! Every minute counts.

Reply 1854

guitardad

10

Can someone please help me with how to approach magnification questions? I haven't done them since unit 1 and can't remember how, but they usually come up as two markers in the papers :frown:

Reply 1855

Tikara

Original post by guitardad

Can someone please help me with how to approach magnification questions? I haven't done them since unit 1 and can't remember how, but they usually come up as two markers in the papers :frown:

they're usually quite simple - just remember to bring a ruler!! :P and it's much easier to measure in mm (for conversion reasons)

Magnification = Image / Actual

you can just rearrange this to find actual if you are given magnification so

Image / magnification = actual

and just make sure your units of image and actual are the same

Spoiler

Reply 1856

Anjna

9

does anyone know where I could find the end of topic chapter questions in the nelson throne book? it's just that some of the pages in my book seem to be missing. :s-smilie:

Reply 1857

guitardad

10

Original post by Tikara

they're usually quite simple - just remember to bring a ruler!! :P and it's much easier to measure in mm (for conversion reasons)

Magnification = Image / Actual

you can just rearrange this to find actual if you are given magnification so

Image / magnification = actual

and just make sure your units of image and actual are the same

Spoiler

Thank you! :smile:

(I'm gonna have to rep you tomorrow I've run out of rep! )