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    hey can someone provide me with
    jan 2011 mark scheme
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    (Original post by daughterofaprince)
    hey can someone provide me with
    jan 2011 mark scheme
    Page 8 of this thread lol
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    (Original post by lbavfc)
    In terms of DNA profiling and gel electrophoresis, do we need to know that STRs are used or just call them DNA fragments?
    DNA fragments and STRs are not the same thing. DNA fragments could be any DNA sample, wherease Short tandem repeats are specific micro-satellites that are unique to every individual and therefore are used for the identification of individuals. Please do correct me if I am wrong.
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    (Original post by InItToWinItGetIt?)
    what the..? is that even on the spec?
    Yeah it is. in the section on interpreting graphs on peat bogs, dendrachrnology, frozen isotopes and radio carbon dating. So Wiggle matching is involved by callibrating the graphs but I am not quite sure how so want a exact answer to my question. So do you know anything about that?
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    (Original post by Schoolio93)
    Yeah it is. in the section on interpreting graphs on peat bogs, dendrachrnology, frozen isotopes and radio carbon dating. So Wiggle matching is involved by callibrating the graphs but I am not quite sure how so want a exact answer to my question. So do you know anything about that?
    Nope don't know anything. The spec doesn't need you to know about it I don't think.
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    Is there a june 2009 paper for this exam available, or did they only start in jan 2010?
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    (Original post by GraceO92)
    Is there a june 2009 paper for this exam available, or did they only start in jan 2010?
    Jan 10 was the first ppr for this unit.
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    (Original post by InItToWinItGetIt?)
    what the..? is that even on the spec?
    We dont need to know it, but its ind green book ann fullick
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    (Original post by darkiee)
    We dont need to know it, but its ind green book ann fullick
    so what exactly do we need to know for that specific section?!?!?

    PS: Are you doing both Unit 4 & 5 papers this sitting?
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    (Original post by PHOLIO)
    answer non QWC questions in bullet points?
    Is it allowed? My lecturer encourages us to write in sentences.
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    Can any1 explain how 1 gene can give rise to more than one protein through post-transcriptional changes to mRNA? Wat exactly are the post-transcriptional changes? Dont really understand the explanation from HSW.
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    (Original post by DLZF)
    Can any1 explain how 1 gene can give rise to more than one protein through post-transcriptional changes to mRNA? Wat exactly are the post-transcriptional changes? Dont really understand the explanation from HSW.
    Genes code for proteins. Genes contain a genetic code which is made up of codons which each code for a particular proteins (or start/stop signal). However, all the codons in genes do NOT code for proteins. There are some parts of the genes which do code for proteins or amino acids and there are some parts of the genes which do not code for proteins or amino acids. The coding parts are called exons and the noncoding parts are called introns. So introns are basically junk DNA. They code for nothing, really.

    But what is transcription? Well, transcription makes mRNA versions of genes on DNA. These mRNA molecules then line up at ribosomes to be translated. But why on earth would we want to have junk coding in our mRNA (and thus protein chain)? We must therefore have some way of removing these introns. So after transcription (POST-TRANSCRIPTION), these introns are splcied out from the mRNA molecules using spliceosomes. Spliceosomes splice out introns from the mRNA molecules and splice together the exons. These exons can actually be spliced together in different orders. What does this mean then? What do you think? What if we had one mRNA chain and it's exons can be arranged differently. This means we can end up with different mRNA chains and so different proteins.

    So 1 gene doesn't have to code one protein. Through splicing, introns are removed and exons are glued together. However, because these exons can be arranged in different orders, we get different orders of amino acids and so diifferent proteins.

    That's a very basic outline. I may have made an error in talking about how exons are spliced back together. I'm really sleepy now as well. I'm off.
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    (Original post by DLZF)
    Can any1 explain how 1 gene can give rise to more than one protein through post-transcriptional changes to mRNA? Wat exactly are the post-transcriptional changes? Dont really understand the explanation from HSW.
    Basically i think you need to mention:
    -pre-mRNA- when the RNA is transcribed from the DNA. This has all the DNA from the gene- so introns and exons.
    -Exons are the parts that code for the amino acids, so splicosome enzymes cut the exons out of the mRNA strand (splicing)
    -Exons can then be arranged in various different sequences to form a single strand
    So same gene can code for lots of different proteins.

    Theres also something in the book about capping the end of RNA strands so its not attacked by enzymes, but i dont know if thats really relevant for this question
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    (Original post by darkiee)
    We dont need to know it, but its ind green book ann fullick
    That book was so wafflely for this bit, I used the CGP instead for dendrochronology etc.

    (Original post by Schoolio93)
    so what exactly do we need to know for that specific section?!?!?

    PS: Are you doing both Unit 4 & 5 papers this sitting?
    Yep I'm doing both. Cursing my school for not allowing us to do the Unit 4 in Jan. I take it you are as well?
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    (Original post by Schoolio93)
    so what exactly do we need to know for that specific section?!?!?

    PS: Are you doing both Unit 4 & 5 papers this sitting?
    Yes, I am doing both. I did Unit4 in jan. and I realised most of my mistake. The Jan paper was a *****, the question 1b(iii) scared me from the start. I have realised my mistake doe. Just stay calm read the question PROPERLY and you will be fine. I redid the paper calmly and i did pretty well. Just hope Mondays paper is Nice.

    Unit 5 I havent read properly AT ALL, am gna do that after my Chem on Wednesday.
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    (Original post by InItToWinItGetIt?)
    That book was so wafflely for this bit, I used the CGP instead for dendrochronology etc.



    Yep I'm doing both. Cursing my school for not allowing us to do the Unit 4 in Jan. I take it you are as well?
    Mainly what we had to know was Dedrochronology and Dendroclimatology and how increase in temperatue affects plants and animals, its effect on organism. and peat bog and frozen isotopes. And Brine shrimp experiment
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    hey, which core practicals do we need to know for this unit?
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    (Original post by darkiee)
    Mainly what we had to know was Dedrochronology and Dendroclimatology and how increase in temperatue affects plants and animals, its effect on organism. and peat bog and frozen isotopes. And Brine shrimp experiment
    Yep got all of them. Fingers crossed this exam goes well.
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    (Original post by mooniibuggy)
    hey, which core practicals do we need to know for this unit?
    Describe how to carry out a study on the ecology of a habitat to produce valid and reliable data (including the use of quadrats and transects to assess abundance and distribution of organisms and the measurement of abiotic factors, eg solar energy input, climate, topography, oxygen availability and edaphic factors).

    Describe how to investigate the effects of temperature on the development of organisms (eg seedling growth rate, brine shrimp hatch rates).

    Describe how DNA can be amplified using the polymerase chain reaction (PCR).

    Describe how gel electrophoresis can be used to separate DNA fragments of different length.

    Describe how to investigate the effect of different antibiotics on bacteria.
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    (Original post by InItToWinItGetIt?)
    Yep got all of them. Fingers crossed this exam goes well.
    Outline the causes of global warming — including the role of greenhouse gases (carbon dioxide and methane, CH4) in the greenhouse effect.

    Describe the effects of global warming (rising temperature, changing rainfall patterns and seasonal cycles) on plants and animals (distribution of species, development and life cycles).

    Explain the effect of increasing temperature on the rate of enzyme activity in plants, animals and micro-organisms.


    Describe how to investigate the effects of temperature on the development of organisms (eg seedling growth rate, brine shrimp hatch rates).

    Analyse and interpret different types of evidence for global warming and its causes (including records of carbon dioxide levels, temperature records, pollen in peat bogs and dendrochronology) recognising correlations and causal relationships.

    Describe that data can be extrapolated to make predictions, that these are used in models of future global warming, and that these models have limitations.

    Discuss the way in which scientific conclusions about controversial issues, such as what actions should be taken to reduce global warming or the degree to which humans are affecting global warming, can sometimes depend on who is reaching the conclusions.

    Thats all we need to know about global warming
 
 
 
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