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AQA BIOL2 Biology Unit 2 Exam - 26th May 2011 watch

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    (Original post by Aimo_1)
    Thank's so much, so whenever it's referring to mass of DNA think about replication?

    I'm assuming mass of DNA halves in Telophase because of the cell splitting into two
    Yes that's right
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    (Original post by angel1992)
    yh that is true, but then how would you suggest alleles are part of the same gene because alleles have slightly different polypeptide chains, yet they are part of the same gene, this must mean that the change that creates the allele will give that allele abiltiy to product a different colour yet it would still be the same gene

    overall would it be easier to say the defintion of a gene is that it codes for a particular charcetristic to prevent confusion?
    Yes that is correct, for example the gene that codes for you eye colour, an allele of this gene that codes for you eye colour will give another colour. So in essence the coded information is very much similar however a gene that codes for brown eyes may have an allele that codes for blue eyes.

    The simplest definition for a gene and allele I would learn is that, a gene is a section of DNA that contains the coded information for making polypeptides. And for allele, an allele is an alternative form of a gene.

    Hope that helps
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    (Original post by ScienceGeek3)
    Yes that is correct, for example the gene that codes for you eye colour, an allele of this gene that codes for you eye colour will give another colour. So in essence the coded information is very much similar however a gene that codes for brown eyes may have an allele that codes for blue eyes.

    The simplest definition for a gene and allele I would learn is that, a gene is a section of DNA that contains the coded information for making polypeptides. And for allele, an allele is an alternative form of a gene.

    Hope that helps
    thankyou i think im gonna stick to your definition as it makes it easier to think about because going into too much thought makes it harder to process as i think there can be many exceptions/conventions in genetics for simplifcation.
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    (Original post by liviaaa)
    The spec says "Names are required only of the cronary arteries and of blood vessels entering and leaving the heart, liver and kidneys."

    It was the first Q on one of the previous papers?

    Liver - Hepatic Vein/Artery and Hepatic Portal Vein

    Kidneys - Renal Vein / Artery
    Oh wow, must have missed that one, i'll be sure to remember them for tomorrow
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    (Original post by ScienceGeek3)
    Oh wow, must have missed that one, i'll be sure to remember them for tomorrow


    Explain how bacteria may become resistant to more than 1 antibiotic.
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    (Original post by nasira372)
    Can anyone summarise all they know about oxygen dissociation curves. It covers like 1 page in my textbook but there have been Qs on it every exam paper
    In the lungs, there is a high partial pressure of oxyen, and in the respiring tissues, there is a low partial pressure of oxygen.
    When there is an increase in CO2, the haemoglobin unloads oxyen more readily to the respiring tissues, therefore the Bohr shift curve moves to the right.
    When animals, like llamas for example, live at a high altitude, where there is a limited supply of oxygen, their haemoglobin has a high affinity for oxgen at low partial pressures, so the Bohr shift curve moves to the left.
    So, if you are given numbers on the graph in the exam, use them to compare what the percentage saturation of oxygen is at a given partial pressure. For example, at 2kPa of oxygenn, a human may have a 50% saturation of oxygen in their haemoglobin, but at the same partial pressure, a llama might have 85% saturation of oxygen in their haemoglobin.

    hope this helps?
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    (Original post by liviaaa)


    Explain how bacteria may become resistant to more than 1 antibiotic.
    The resistance gene may be passed along from one species of bacteria to another species via horizontal gene transmission. The plasmid may also be passed down from one generation to the next via vertical gene transmission.

    Explain ways in which variation may occur as a result of meiosis?
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    What do people think the 6 mark question will be on?
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    http://www.familyguyx.net/episode/fo...irs/link_1691/

    family guy break!!
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    (Original post by ScienceGeek3)
    The resistance gene may be passed along from one species of bacteria to another species via horizontal gene transmission. The plasmid may also be passed down from one generation to the next via vertical gene transmission.

    Explain ways in which variation may occur as a result of meiosis?
    -Crossing over - different combinations of alleles are made, due to chromosomes swapping alleles, forming bivalents during metaphase.

    -Random Segregation - The way inwhich the chromosomes are lined up on the equator during metaphase, causes them to enter 1 cell vs the other.

    Diffucluties in defining a species?
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    (Original post by Saraah_x)
    What do people think the 6 mark question will be on?
    I think it'll either be structure/function of blood vessels (maybe comparisons), ventilation in fish and/or insects or movement of water through plants.

    i just hope it'll be an easy question.
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    (Original post by liviaaa)
    -Crossing over - different combinations of alleles are made, due to chromosomes swapping alleles, forming bivalents during metaphase.

    -Random Segregation - The way inwhich the chromosomes are lined up on the equator during metaphase, causes them to enter 1 cell vs the other.

    Diffucluties in defining a species?
    Geographical isolation meaning it is not feasible to see if the species can breed to form living, fertile offspring. The species may have different characteristics due to mutations ?

    How do antibiotics kill bacteria?
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    Can someone please explain how you can deduce when "DNA replication" and all that Growth 1, Synthesis 1, Growth 2 occurs in the cell cycle? Like interpreting it from a graph
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    Hey...
    I am sort of starting to freak out for Biology 2 as I've had other exams all week...
    Does anyone have any concise predictions of what might come up tomorrow? We all know that fishes are gonna come up as it hasn't in a few years... Any other good guesses?
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    (Original post by EffKayy)
    Can someone please explain how you can deduce when "DNA replication" and all that Growth 1, Synthesis 1, Growth 2 occurs in the cell cycle? Like interpreting it from a graph
    DNA replication occurs in synthesis 1. It would be shown by the mass of DNA incresing. The Growth 1 and Growth 2 would become for and after S1 respectively and would not lead to an increase in the mass of DNA, rather a constant increase in the general mass of the cell (proteins/ organelles being synthesised)
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    Hey guys what is the monomer that makes up glycogen ?? Is it a-glucose just more branched than amylopectin ?
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    (Original post by EffKayy)
    Can someone please explain how you can deduce when "DNA replication" and all that Growth 1, Synthesis 1, Growth 2 occurs in the cell cycle? Like interpreting it from a graph
    Cell mass increases consistently during interphase. DNA mass only during S phase.
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    (Original post by Aimo_1)
    Q4 Jun 2009,

    Why is the Mass of DNA in the sperm cell a quarter of the mass of DNA in prophase?
    Explained around these pages:

    http://www.thestudentroom.co.uk/show...php?p=31699461
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    (Original post by RoadRunner)
    Hey guys what is the monomer that makes up glycogen ?? Is it a-glucose just more branched than amylopectin ?
    Yeah the monomer is a-glucose. They are just short chains of highly branched a-glucose monomers.
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    Really need to go through all past papers again and revise over Tissue Fluid properly. Thanks for all those people who helped me! Will rep when I have time.
 
 
 
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