Edexcel A2 Biology Unit 5 (6BIO5) - 22/06/2011- OFFICIAL THREAD !

Did you revise AS stuff for the exam?

i was going to ask, i read something about ATP synthase, do the protons H+ or the electron provide the energy to combine ADP and Pi to form ATP?or does this enzyme do this (or does it catalyse this reaction)?

Could someone pleeeeaasssee help me with question 2 a) i) from the jan 2011 paper about critical periods for flowering? It is probably really obvious as it is only 1 mark but I just don't understand the answer! Thanks in advance!

Technically, it could be either.

However we have been taught that generally an increase in heart rate is due to low pH and a decrease is due to high pressure.

There are receptors for both pressure and pH. What we have been taught is that for exercise it will be the chemoreceptors. This is because during exercise, as you probably know CO2 levels rise causing pH to go down. This means more oxygen is needed for respiration so the heart pumps faster due to a nerve impulse from the sympathetic nerve.

Post exercise it will most likely be responding to pressure. This is because CO2 levels will be lower due to the oxygen debt being repaid and then there will just be high pressure from a heart pumping harder.

Some questions I found from another thread:

Questions with a *star* require careful consideration and thinking.


1)Suggest two ways by which endurance can be enhanced.

2)Based on your knowledge and Mantyranta's condition , describe the working of an anabolic steroid.

3)Suggest how kidney failure or AIDS could lead to anemia.

4)In 1989 , the biotech company Amgen began marketing Epogen,an injectable form of epo produced by recombinant bacteria.Describe the risk of using genetically modified organisms.

5)"Doping is a part of the business cycle"
Outline the ethics of using performance-enhancing drugs.

6)*Blood and urine of athletes are routinely tested at every competition.Suggest why two samples are taken of each blood and urine?

7)Charles Yesalis , an epidemiologist at Pennsylvania State university has interviewed more than a thousand athletes who have admitted to taking banned drugs.Give reasons to show whether this statement is reliable or unreliable.

8)What is the risk involved in injecting epo in healthy individuals?

9)*Explain the difference b/w correlation and causation.Use the data on page 3 to assess the relationship b/w using adenovirus and increase in muscle mass , to AAV's to determine the epo delivered to mice and monkeys.

10)*With reference to page 4 , 'all forms of epo are produced by a single gene'.Explain how post transcriptional changes can give rise to more than one protein from a gene.

11)Suggest the risks involved in IGF-1 gene therapy.

12)Explain the problems encountered by scientists for administering IGF-1 therapy.

13)*Describe the role of primary and secondary immune response's following IGF-1 gene injection in to the body.

14)*"The stakes in modern sports are high both in prestige and in money".
Which lines from the article support this idea.
Page ________________________________ _____________________
Lines___________________________ __________________________

15)Describe an absolutist's and relativist's ethical position on the proposal to set a maximum total of RBC's count for athletes rather than measure EPO level.

16)Outline the role of transcription factors in the control of gene expression.

17)*How would a change in temperature effect the working of a proteosome.

18)Explain the mechanism of actional potential with reference to para 1 on page 8.

19)Describe the structure of a muscle fibre.

20)Why is increase in muscle mass alone , not of great help to athletes?

21)State two conditions in which using gene therapy for increasing muscle mass is advantageous other than sports.

22)*Why is it easier for athletes to tamper the results of EPO testing?

23)*Outline all the methods given in the article by which muscle performance can be enhanced referring to any ethicla and safety issues.

http://www.thestudentroom.co.uk/showthread.php?t=1580084&page=2

Does anyone have a MS to go along with them?

would they ever ask a question like 14??? i thought you can do the artcile without having read it, as in using ur knowledge form the topic, (dat is worrying becasue it so specific?)????

Could someone explain the bit in bold please? I don't get what it means.. I thought genes were turned on by transcription factors (i.e. chemical stimulus). Thanks

Scientists believe that hard exercise, the kind that leaves you sore the next day, builds muscle by inducing microscopic damage to the muscle fibres. These “micro tears” are repaired by beefing up the fibres with extra proteins so they will be adapted to the exercise the next time. A protein called insulin-like growth factor 1 (IGF-1), which is turned on by mechanical signals such as stretch or exercise overload, seems to play a role in this repair process. IGF-1 exists in at least five different forms, whose parts are spliced together in different ways. All the forms are produced by a single gene.

Could someone explain the bit in bold please? I don't get what it means.. I thought genes were turned on by transcription factors (i.e. chemical stimulus). Thanks



If I am honest I have no idea lol. I just copied those questions from another thread.

There was a 7 mark question in a previous paper that asked you to list all the risk and benefits of a treatment that were listed in the article. So maybe, the could, don't know.

You are absolutely right...

byt
you have to imagine the body as an intercommunicating organs rather than isolated cells... these cells are constantly in communication and any change can lead to the activation of certain chemicals...

whether this be a mechanical signal or a chemical signal (like a hormone)... the true details are too complicated and probably not known as of yet...

if you are interested, i found this from Goldspink's article:

However, mechanical signals are known to influence gene expression in muscle (10) and in other musculoskeletal cell types, including fibroblasts and osteoblasts.

The mechanical signal would lead to the activation of specific transcription factors.... the mechanical signals would be identical to a hormone in that it leads to the activation of transcription factors.... we have just been taught that hormones are chemical signals that bind to the receptors etc. etc...... however, why not be a mechanical signal... or an optical signal? there has been recent work on optogenetics (bloody interesting).. light induces transcription factors and leads to mRNA synthesis....

thanks. yeah im really unsure aswell, really starting to hate this article, i just dont see the point in it, and i feel like i dont want to waste time going over it when other topics need revising (it so long winded, and i cant stand the way its written, like when it mentions irrelavant stuff (95% of the time) like ur not gonna get arms like madonna just trough gene doping? grrrr

Ah yes thank you. Very well explained + rep

So say they ask how is the protein IGF-1 turned on. Would just say environmental or mechanical signals such as stretch or exercise overload are detected by receptors which lead to transcription factors being activated... etc etc.?



Yeah I really don't know what they may ask on this. I'm just going through it as we speak, and underlying and highlighting topics anything I think they could ask.

Like for e.g. Page 6, paragraphs 1 and 2, I've made a note that they could ask how you look for viral DNA in an athlete as a method to catch cheaters. So it would involve biopsies and then analysing the cell for the viral DNA, as the virus when it infects the cell, incorporates it's DNA into the host cell's DNA. This probs won't come up, but it's edexcel, they seem to want you to 'apply' your knowledge a lot

EDIT: Or like compare different methods mentioned in the article to detect gene doping?

And haha it mentions Madonna?! - I guess I'm not upto that bit yet

EDIT 2: hah just read it. at least it's there's that made me smile a little when reading the article lol

good idea, might start doing that aswell, do you think they could ask you on anything mentioned in the article, as in something really insignifcant only mentioned in one pragraph (eg in one paragraph it says something about cardiac cycle or bloss vessel, so could it say describe the structure/function of arteries etc like from AS)
and therefore are most question going to be based on the main topic of gene doping and transcitpion factors ? (do you have any clue from past paper)
sorry if im not making sense!?

How much detail do you think we need to go into on the kreb cycle. Must we go through all of it, or do we just say that ...

Acetyl CoA combines with a 4-carbon compound to produce a 6-carbon compound.
This 6-Carbon compound then goes through a series of reactions which eventually regenerates the 4-Carbon compound.
In the process, 2 molecules of CO2, 3 molecules of reduced NAD, 1 molecule of reduced FAD, and 1 molecule of ATP are produced.

Would we have to go into detail on 'the series of reactions', or do you think this is ok.

Could someone help me out here. Thanks

Page 9, Paragraph 4

While there are valid medical and space applications for anti-wasting drugs, as a safer alternative to steroids they will inevitably be hugely tempting for athletes too, not to mention the lazy as well.

I really don't get the bold bit. Could someone explain the difference between ''anti-wasting'' drugs and ''steroids'' in the context of the article? Don't get this bit at all.

It mentions ''steroid'' twice in the article, one above and the other on page 7, paragraph 2

The use of anabolic steroids is being explored for some conditions. But these compounds have a huge range of effects on the body besides promoting muscle growth, some of them undesirable, and only appear to work well in conjunction with exercise. A specific treatment to prevent wasting until patients are well enough to get back on their feet, or until astronauts have arrived at their destination, would be ideal.

I still have not read the article (is that bad?), but i take it anti-wasting drugs simply maintain the muscle you already have, but steroids help to increase the developement of muscle. So one is maintaining muscle, and the other is increasing production.

Also, have you done any unit 5 past papers ... if so, is it very synoptic, or is it just 1-2 random questions like the cellulose question back in jan 2011 for unit 4