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AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

Stage one is saying you add the primers to the "mixture" and stage 2 is the attaching of the primers to the single DNA strands

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And the cooling down causes that I guess?
Thank you!!

Why the neg?? " the mixture is cooled to 55degrees, causing the primers to join/anneal to their complementary bases at the end of the DNA fragment."

(edited 10 years ago)

Reply 2161

master y

12

Original post by safis

Just a heads up: I was told that a future essay question on energy transfer might come up. I was told this last year so might come up on this paper.

how/who told you this? :s-smilie:

Reply 2162

marleyxd

Original post by ConorP

Thanks, I think it's when you apply that to the oestrogen cycle.. Everything seems to inhibit and stimulate everything haha :s-smilie:

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Yeah, with the Oestrous cycle, the majority of feedback is negative e.g Oestrogen and Progesterone inhibiting FSH and LH from the pituitary gland. However there is Positive feedback involved when Oestrogen levels reach a certain point, which then stimulates the production of FSH an LH.

Reply 2163

HELPIMSTUCK

Essay plan ideas on biological importance of water (I feel this may come as its quite a broad topic, like bacteria and cycles):

Spoiler

Obviously I wouldn't write all this. Some topics relate to other titles
- Cholera relates to bacteria, disease
- Cystic Fibrosis relates to genetics, disease, gene therapy
- Osmosis (might be an essay in itself)
- Osmoregulation, Thermoregulation relate to negative feedback

Reply 2164

khalidpatel

8

Guys 1 quick question, describe the biological consequences of pollution of water by sewage? 4 marker need help I'm kinda confused

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Reply 2165

hannahs14

Original post by samfreak

yh im stuck on this aswell :-( can someone please help us?

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you are right the textbook is wrong..our strand is the complementary copy. Don't trust the textbook, my teacher says its flooded with mistakes.

Reply 2166

hannahs14

Original post by mathsguy

I think there'll be an essay on controls, practical investigations and statistical tests

Also something to do with proteins

That was tested in our EMPA/ISA how could they do it again? Furthermore how could you relate it to all 4 units?

Reply 2167

hannahs14

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
?

Isn't homeostasis too narrow? I would think it would be a broader question? How can you relate homeostasis to units 1 and 2??

Reply 2168

gingerandice

1

how can thermoreceptors send nerve impulses to the hypothalamus via the autonomic nervous system? I thought the ANM was between the coordinator and the effector?

Reply 2169

SamEastie

2

i do not know how to prepare for the essay!? theres no way i can learn all 4 units by monday.. or ever :L
how are other people doing it? :/

Reply 2170

marleyxd

Original post by gingerandice

how can thermoreceptors send nerve impulses to the hypothalamus via the autonomic nervous system? I thought the ANM was between the coordinator and the effector?

No the autonomic nervous system is functions unconsciously (you don't need to control it)
I think you're thinking of a motor neuron....

Reply 2171

Med_me

Original post by sienna5

A fluorescent marker is basically a marker gene that codes for fluorescence. And the point of a marker gene is to identify cells that have been transformed ( the host cells that's actually taken up the vector and Dna)

Ah, thanks!

Reply 2172

F1's Finest

21

Original post by hannahs14

That was tested in our EMPA/ISA how could they do it again? Furthermore how could you relate it to all 4 units?

Exactly.

The only questions they will ask for the essay are ones where we can bring in topics from all units of the entire A-Level spec.

Reply 2173

ropin1

hi, just wondering if an essay came up about the biological importance of water could you link in points about eutrophication, and how the contamination of water can have negative impacts on organisms. Ive just retaken unit 4 so thats still fresh in my mind

Reply 2174

JoshL123

2

Hey everyone, if an organsims is in a favourable environment, does it turn a lot more often?

Reply 2175

ActaNonVerba

Original post by khalidpatel

Guys 1 quick question, describe the biological consequences of pollution of water by sewage? 4 marker need help I'm kinda confused

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nitrate in faeces.. causes eutrophication (you have to explain it obv)

Reply 2176

Tikara

Original post by JoshL123

Hey everyone, if an organsims is in a favourable environment, does it turn a lot more often?

It'll turn more often - in order to stay in that environment for longer :smile:

I think the text book is wrong on that bit

Reply 2177

JoshL123

2

Original post by Tikara

It'll turn more often - in order to stay in that environment for longer :smile:

I think the text book is wrong on that bit

Thought so! I was getting so confused as people were saying the opposite haha! Thanks :smile:

Reply 2178

Anjna

9

what is the exact definition of a primer?

Reply 2179

ConorP

Original post by MegMoo12

And the cooling down causes that I guess?
Thank you!!

Why the neg?? " the mixture is cooled to 55degrees, causing the primers to join/anneal to their complementary bases at the end of the DNA fragment."

Yeah I agree, don't know what you mean why the neg?

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AQA BIOL5 ~ 17th June 2013 ~ A2 Biology

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