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tn234
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#2881
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#2881
(Original post by emah123)
thank you! do you know which units are most relevant to biol 5?
I'm not quite sure, sorry, trying to work it out myself because I swear the legacy unit 5 is unit 4
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flyylikejetz
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#2882
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#2882
(Original post by Anjna)
hey guys I completely forgot but when working calculating length of image ect to convert it into um from mm do you x1000 ?
yepp measure in mm and x1000 to get to um
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tn234
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#2883
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#2883
Also would it be likely for AQA to repeat the old spec essay questions so would it be worth learning the essay plans for them?
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flyylikejetz
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#2884
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#2884
In genetic fingerprinting are DNA probes added just so the fragments are all visible ?
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gingerandice
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#2885
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#2885
(Original post by tn234)
I'm not quite sure, sorry, trying to work it out myself because I swear the legacy unit 5 is unit 4
http://www.school-portal.co.uk/Group...GroupID=870320
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gingerandice
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#2886
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#2886
(Original post by flyylikejetz)
In genetic fingerprinting are DNA probes added just so the fragments are all visible ?
I believe so.
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tn234
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#2887
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#2887
Thank you!!
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gingerandice
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#2888
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#2888
how exactly does the myelin sheath prevent the creation of an action potential?
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pjanoo
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#2889
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#2889
(Original post by flyylikejetz)
In genetic fingerprinting are DNA probes added just so the fragments are all visible ?
Yes. Genetic fingerprinting usually involves comparing between 2 or more fingerprints, so you'd just need to be able to see the bands.

In other cases they'd be used to make specific genes visible, like a faulty CFTR gene for cystic fibrosis, allowing them to be identified if present.
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jonnyb123
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#2890
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#2890
Does anybody have a list of possible essays I could make some plans for?
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mollymango
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#2891
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#2891
I am fairly confident with the Unit 5 questions and stuff now, it's just the synoptic essay worrying me. What topics do you think are likely to come up? What do you think in terms of AS and unit 4 I should focus on tomorrow?
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medlou
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#2892
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#2892
Can someone please help me with this Ive posted twice already!

I am very confused with the relationship between body temperature and respiration, I know its simple but it doesn't make sense to me!

I thought that when the body is cold, it increases respiration in order to generate heat
But in one of the exam papers, it shows an increase in body temp along with an increase in oxygen consumption and asks why.
The mark scheme says :
increased temp leads to increased kinetic energy/rate of reactions/increases metabolism
More energy/ATP
Oxygen consumption linked to respiration

This is saying that increased body temp increases respiration, whereas I thought that it was respiration which increased body temp?




I am also confused where it says more ATP, does that mean more ATP is needed or more ATP is generated? I cant quite see how it all links together.
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gingerandice
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#2893
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#2893
what exactly would you say if asked how an action potential is propagated in an umyelinated neurone?
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gingerandice
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#2894
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#2894
I think it means that the temperature increases enzyme activity- as enzymes control metabolic activity such as respiration , the rate of respiration increases, therefore the rate of oxygen, a reactant of respiration, increases. The higher temp is a more optimal temperature for the enzyme. yh the homeostasis questions get me too.
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henryoloyede
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#2895
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#2895
(Original post by gingerandice)
how exactly does the myelin sheath prevent the creation of an action potential?
The voltage-gated ion channels are found only at the nodes of Ranvier, and between the nodes the myelin sheath acts as a good electrical insulator. The action potential can therefore jump large distances from node to node, a process that is called saltatory propagation. This increases the speed of propagation dramatically, so while nerve impulses in unmyelinated neurones have a maximum speed of around 1 ms-1, in myelinated neurones they travel at 100 ms-1.
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pjanoo
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#2896
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#2896
(Original post by medlou)
Can someone please help me with this Ive posted twice already!

I am very confused with the relationship between body temperature and respiration, I know its simple but it doesn't make sense to me!

I thought that when the body is cold, it increases respiration in order to generate heat
But in one of the exam papers, it shows an increase in body temp along with an increase in oxygen consumption and asks why.
The mark scheme says :
increased temp leads to increased kinetic energy/rate of reactions/increases metabolism
More energy/ATP
Oxygen consumption linked to respiration

This is saying that increased body temp increases respiration, whereas I thought that it was respiration which increased body temp?




I am also confused where it says more ATP, does that mean more ATP is needed or more ATP is generated? I cant quite see how it all links together.
That is quite confusing haha! I just remember this:

Respiration is an exothermic reaction so heat will always be generated, so you've got it spot on that the body will increase its rate of respiration to increase the heat generation.

Don't forget though that respiration is an enzyme-controlled reaction. As temperature increases, kinetic energy of molecules increases and so enzyme activity will increase - increasing the rate of respiration.

Respiration produces ATP, so now with the greater the rate of respiration, more ATP is going to be produced.

Respiration also runs on oxygen as fuel, so more oxygen is needed to continue fuelling this greater rate of respiration.

It is weird how it seems contradictory and I think that's because there's more complexity to respiration than the specification will cover without going beyond A-Level. I really hope this helps!!
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mollymango
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#2897
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#2897
(Original post by medlou)
Can someone please help me with this Ive posted twice already!

I am very confused with the relationship between body temperature and respiration, I know its simple but it doesn't make sense to me!

I thought that when the body is cold, it increases respiration in order to generate heat
But in one of the exam papers, it shows an increase in body temp along with an increase in oxygen consumption and asks why.
The mark scheme says :
increased temp leads to increased kinetic energy/rate of reactions/increases metabolism
More energy/ATP
Oxygen consumption linked to respiration

This is saying that increased body temp increases respiration, whereas I thought that it was respiration which increased body temp?




I am also confused where it says more ATP, does that mean more ATP is needed or more ATP is generated? I cant quite see how it all links together.
Is the question related to an endotherm or an ectotherm? If it is an ectotherm (so a reptile or fish etc) then the increase in heat means metabolic rate increases as the enzymes have more kinetic energy, thus more ATP is needed so oxygen consumption increases for increased respiration. Endotherms metabolic rate is always high
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BobTheBuilder94
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#2898
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#2898
Please can some kind soul help me with DNA probes onwards.. I understand that DNA probes are short single strands of DNA with complementary bases to the Target gene, and we can use DNA probes that are radioactively or flurescently labelled to see if there's a mutated target gene. But to use a DNA probe we have to find the base sequence first by the Sanger method.. I don't see how this produces the sequence? In the Nelson Thornes textbook p267, it says many single stranded fragments of the sequences of DNA are added, these act as template strands for synthesis...I don't get this at all.. are these the target gene sequences?? Also I don't understand Restriction mapping do we use it to cut a length of a dna fragment out in order to put a new one in??
Helllp is appreciated
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henryoloyede
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#2899
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#2899
(Original post by jonnyb123)
Does anybody have a list of possible essays I could make some plans for?
Our teacher gave us a list of essays:

1. Discuss the issues associated with the use of recomibnant DNA.
2. Discuss the influences humans may have over species diversity.
3. Discuss the different ways organisms use ATP.
4. How do amino acids get from our food to becoming proteins in the body?
5. Discuss negative feedback and its importance in biology.
6. Polymers have different structures and functions. Describe how the structures of different polymers are related to their functions.
7. The transfer of energy between different organisms and between these organisms and their environment.
8. Cycles in biology.
9. How bacteria affect human lives.
10. Protein synthesis as a fundamental process to life.
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mollymango
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#2900
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#2900
(Original post by jonnyb123)
Does anybody have a list of possible essays I could make some plans for?
I would quite like this list too haha!

I think I am going to revise enzymes and proteins, diseases, and the transport of substances. Maybe the uses of ATP too (that would be an awesome essay aha).
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