Edexcel GCE Biology Unit 5 6BI05 June 2013

Original post by super121

Can someone please explain to me the sympathetic and parasympathetic nerves. I know what they do, but where do they come in? Thanks :smile:

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May I ask what you mean by where do they come in?

Reply 762

HQazi

9

Guyssss help here
Any questions for practise? :frown:

aside from the past papers have done them a lot
Thanks!

Reply 763

Original post by jojo1995

thank you so much .. lovely definition :smile:

I try to cram in as much marking points as possible

Reply 764

Sly1

6

Original post by super121

Can someone please explain to me the sympathetic and parasympathetic nerves. I know what they do, but where do they come in? Thanks :smile:

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They are used in control of heart rate and also the pupil reflex

Reply 765

Mjwilson1988

Original post by Lujain Al Omari

3 ATP molecules are produced per glucose molecule. 32-38 molecule of ATP are produced in the whole process due to oxidation of NADH and whatnot in the electron transport chain. When asked about how many ATP molecules are produced per glucose molecule, they are talking about substrate level phosophorylation. 32-38 molecules are the net of oxidative and substrate level phosphorylation

That is per glucose molecule though, all the substrates (not enzymes) for the Krebs Cycle and ETC are produced from that glucose molecule. If they were asking how much is produced per glucose for Glycolysis, then yeah, 2 is your answer (you use 2 to phosphorylate glucose, then you get 4 off as phosphorylated glucose is converted to pyruvate). However, during Aerobic respiration you can use the products of glycolysis to go on to the Links reaction, Krebs and ETC. So one molecule of glucose produces 36, because the following reactions are from that one glucose molecule.

Reply 766

what points would i write if i was given a question on nature vs nurture roles in development ?

Reply 767

ebc

Do we need to know all the stages in the Cholodny-Went model? Thanks :smile:

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Reply 768

Original post by Lujain Al Omari

I try to cram in as much marking points as possible

aww i need to start doing that :tongue:

by tghe loks of things it really works

Reply 769

Brad0440

Suggest why a dispersive morph in naked mole-rat colonies helps with the continuation of the naked mole-rat species. (2)

Spoiler

Naked mole-rats have DNA fingerprints that have coefficients of band sharing ranging from 0.93-0.99.

Outline the process that occurs to produce these DNA fingerprints. (5)

Spoiler

An extracellular molecule may be able to be applied to humans as an injection or drug to treat cancer. [Paragraph 30]
What are the normal stages of testing that must be gone through to allow this treatment to be sold as a treatment for cancer? (4)

Spoiler

I'll try and post some more questions in a bit, but if not I will when I get back from work later today.

Reply 770

Original post by Mjwilson1988

That is per glucose molecule though, all the substrates (not enzymes) for the Krebs Cycle and ETC are produced from that glucose molecule. If they were asking how much is produced per glucose for Glycolysis, then yeah, 2 is your answer (you use 2 to phosphorylate glucose, then you get 4 off as phosphorylated glucose is converted to pyruvate). However, during Aerobic respiration you can use the products of glycolysis to go on to the Links reaction, Krebs and ETC. So one molecule of glucose produces 36, because the following reactions are from that one glucose molecule.

What you're saying is true. I think the phrasing of the question is the trick here

Reply 771

Original post by Brad0440

Suggest why a dispersive morph in naked mole-rat colonies helps with the continuation of the naked mole-rat species. (2)

Spoiler

Naked mole-rats have DNA fingerprints that have coefficients of band sharing ranging from 0.93-0.99.

Outline the process that occurs to produce these DNA fingerprints. (5)

Spoiler

An extracellular molecule may be able to be applied to humans as an injection or drug to treat cancer. [Paragraph 30]
What are the normal stages of testing that must be gone through to allow this treatment to be sold as a treatment for cancer? (4)

Spoiler

I'll try and post some more questions in a bit, but if not I will when I get back from work later today.

hi, why is the drug tested on a small group of unhealth individuals ? what is the differnece between the reason for the large grouop of unhealthy individuals and the small group of healthy indivisduals ?

thanks for the qs :smile:

Reply 772

Original post by jojo1995

what points would i write if i was given a question on nature vs nurture roles in development ?

If you mean the development of the visual cortex, then:

The ocular dominance columns are formed during fetal pre-natal development. However, many dendrites and synapses overlap. Also, there is a large number of synapses.
A critical period of the post-natal development if the visual cortex (VC) exists. During this period, the correct light stimulus must be introduced to the eye, so that vital neural connections be successfully made.
Due to the stimulus, every time an action potential passes along an axon and finds its target cell in the VC, neurotransmitters are released, which establish the synapse at the cost of other synapses that are not active. The number of synapses and axons decreases, which is important to ensure that messages are efficiently carried to where they are needed.
Post natal changes to the visual cortex include: the change in size of the occular columns, change in number of synapses and axons, and the change in the length of neurones

Reply 773

Original post by jojo1995

hi, why is the drug tested on a small group of unhealth individuals ? what is the differnece between the reason for the large grouop of unhealthy individuals and the small group of healthy indivisduals ?

thanks for the qs :smile:

so that if the drug is found to have surprising serious side effects, not a large number of people would be victims to them ( to lower number of side effects)

Reply 774

Mjwilson1988

Original post by jojo1995

what points would i write if i was given a question on nature vs nurture roles in development ?

Nature: The genetic influence of development. Your genes will determine when you are going to have a Critical window for development. Using New Born studies you could mention that babies have innate reflexes (such as suckling and finger grabbing) which they have not had time to learn, so are more likely to be from genetic influence, another one is the visual cliff, babies know not to walk over a drop, even though they haven't experienced what would happen if they did. Also, Identical Twin studies where the twins are raised apart in different environments, any similarities they have could be genetic (as they have identical genes). People who suffer strokes and loss of limbs have the ability to learn to talk and redevelop certain skills lost, this shows that the brains neurons are able to change and rewire (and growth is down to transcription, which is genetic).

Nurture: This is the environmental influence on development. Think about making points to do with the visual cortex development, how ocular dominance columns develop only during a critical window and only if they are stimulated (remember how kittens who had their eyes shut at 6 weeks onward would be blind where as if you do the same thing after a year, they will be fine). Twin studies again, any difference in identical twins must be environmental because they are genetically identical. Another one is from Cross Cultural studies, where people develop different depth perceptions depending on what type of surrounding they grow up in (illusions illustrate this, as people from first world tend to live with buildings all at right angles and with loads of cubes, where some tribes in Africa live in very curved houses) so this shows that some aspects of depth perception are gained from what environment you grow up in. Another one to think about is ability to learn, this is heavily influenced by the environment. Rats which grow up in boring environments do not test as well in mazes etc as rats which grow up or live in exciting, more stimulating environments, showing that learning is a lot to do with nature, as more stimulus leads to more synaptic connections, which leads to more brain activity. However, typically, all the rats will still get through a maze, meaning there is some element of nature going on. Habituation and conditioned learning are both influenced by environment, but instincts are very nature influenced.

Remember with this whole topic, Causation is very difficult to prove, are it is extreme hard to get into a situation where you can be certain that only one factor (i.e. genes) are the only thing affecting development.

This is a relatively massive topic and I've not touched on everything, but I think Nature is a lot more difficult to prove that nurture!

Reply 775

Original post by Lujain Al Omari

so that if the drug is found to have surprising serious side effects, not a large number of people would be victims to them ( to lower number of side effects)

oh okay, thank you, but i though that was what the trials on unhealthy people was :redface:

Reply 776

Taylor Swift

Anyone have a plain copy of the scientific article?
How's everyone revising for this?? Just reading it or.. ?

Reply 777

RnTf

5

Original post by joan2468

It's basically a protein that binds to DNA to switch certain genes on or off for transcription - if it switches genes on then it's called an activator, if it switches genes off then it's a repressor. I think at our level that's all we really need to know :P

EDIT : factors that switch on genes are activators, my bad.

Thank you very much. But I am not sure do we have to know the terms activator and repressor.
I know these words are on the CGP revision guide, but I couldn't find them on the thick edexcel book...

Reply 778