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    (Original post by Annaaix_)
    Does anyone have the specimen paper to send to me?
    plspls x
    The specimen for IAL is the same as June 2013 paper, here's for the GCE tho!
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  1. File Type: pdf Biology-Practical-Alternative-SAMs.pdf (701.0 KB, 119 views)
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    (Original post by Annaaix_)
    Yep that's correct! Spearman's Rank tests for correlation within a range and plotting anything with a range of values would be plotted with a line graph or scatter graph (although line is better). T-test and Mann-Whitney are used more for differences between two or more variables, so like testing vit C content in multiple foods, testing males against females, or testing 2 different fields, etc). Makes sense?
    Totally does! Thankyou xx <3
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    (Original post by Aimen.)
    Okay so I've seen alot of people around here wanting to know the predictions for June 2016 paper, although I'm not a paper-setter so I can't be very certain but here's what I came up with
    AS practicals:
    1.Effect of caffeine on heart rate of daphnia- Jan 2012(Q#2)
    2.Vitamin C content of fruit juices- Jan 2013 and June 2015
    3.Effect of temperature on permeability of membranes-June 2010
    4.Enzyme concentration and rate of reaction-Jan 2011,Jan 2015 and Jan 2013
    5.Observing mitosis-Jan 2016
    6.Totipotency and plant tissue culture-(never)
    7.Tensile strength and plant fibres-(never)
    8.Investigating plant mineral deficiencies- June 2013/ Specimen paper IAL
    9.Antimicrobial properties of plants-Jan 2014

    A2 core practicals:
    1.Looking for pattern (ecological studies)- June 2010, Jan 2011 and June 2012
    2.Effect of temperature on hatching rate of brine shrimps/germination- June 2011
    3.DNA Gel Electrophoresis-(NEVER)
    4.PCR- Jan 2014
    5.Effectiveness of antibiotics- Jan 2011, June 2012 and June 2015
    6.Measuring rate of oxygen uptake- Jan 2012, Spoecimen paper GCE and Jan 2015
    7.Investigating breathing- June 2013
    8.Can Snails become habituated to a stimulus?- June 2014

    Well, so the expected topics for this paper (the ones that have never showed up earlier are Electrophoresis, Totipotency and tensile strength).One of them is definately gonna show up!
    But please don't kill me if it doesn't! I'm just as clueless as you people hehe
    Actually totipotency came in one year, it was to investigate the effect of something on plant tissue

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    You guys! I need help! Can someone tell me how to answer the 10 mark question in unit 6b please help!

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    (Original post by Chinu_Cheeku97)
    You guys! I need help! Can someone tell me how to answer the 10 mark question in unit 6b please help!
    1. State dependent variable
    2. state how to measure it/how to derive quantititave value
    3. state independent variable
    4. if it's temperature or something that ranges, state 5 temperatures/values
    5. if it's something you have to extract from an organism, state how you will extract it
    6,7,8 & 9. state 2 variables that need to be controlled and methods to control each, this will give you 4 marks
    10. repeats
    11. timescale
    12. if it's bacteria state that you need aseptic conditions
    13 & 14. you will get 2 marks for quality of writing, so make sure you write in full sentences and use scientific vocab
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    (Original post by Aimen.)
    One little question peeps..
    When we write a null hypothesis, we write something like "There is no significant ..... between ..... and ......"
    So, when we write a hypothesis do we write "There is a significant ...... between ...... and ......"
    or do we write "..... has an effect on ......"???


    When you write a null hypothesis, it's always thers is NO significant correlation/difference

    For writing a hypothesis, you can write there is no or there is a significant correlation/difference and you have to specify the effect

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    (Original post by notsoclueless)
    You follow the procedure for measuring the Vitamin C content by using DCPIP indicator.
    First, you take Vitamin C solution of known concentration and add it using a pipette to the same volume of DCPIP (say 2cm^3) you will use for the duration of the experiment. Find out the volume required to decolourise the DCPIP.
    Next, you cook the vegetable, keep them warm and you may either crush or blend the vegetables and obtain the extracts.
    Independent variable would be the length of time food is stored after cooking.
    Then include what times you're going to use like 0 minutes (which would mean as soon as it was cooked), 3 minutes, 6 minutes, 9 minutes and 12 minutes (you can use your own time intervals)
    Dependent variable would be the Vitamin C concentration
    So as the procedure states, you take a known volume of DCPIP solution (2cm^3) in a measuring cylinder and you add drop by drop of the veggie extract with a pipette, recording the volume required to decolourise the DCPIP at each time interval.
    You write about two other variables that would affect the result and how you would control them.
    Repeat several times.
    Finally, you can find the Vitamin C concentration of the cooked vegetables at each time period by using the formula
    Concentration=
    (conc of Vitamin C used x Vol. of Vitamin C used) /Volume of veggie extract used


    Here's the markscheme
    https://3ef7e8cb3a958922c328db7b6aaf...%20Biology.pdf
    Oh, Thank you
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    (Original post by Aimen.)
    The newer papers as in these IAL ones give medians and range as well. And they even gave this chi-squared test aswell!
    What if they give us gel electrophoresis.What would be the Dependent and independent variables for it?
    i was thinking and maybe they could give us something to do with cystic fibrous and use the chi squared test since its comparing results of observed and expected.
    the punnett square can be drawn for the genotype of the unborn baby.This would be expected.ALSO this would only be the case if one of the parent is affected and the other is a carrier or both are carriers.

    now we carry out the gel electrphoresis of the amniotic fluid obtained,the bands matching which parent will determine whether the baby is affected or not.
    lol this is just my own theory,prolly wont come up as we don't know anything about the other variables.
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    (Original post by PlayerBB)
    Actually totipotency came in one year, it was to investigate the effect of something on plant tissue

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    Ohh I guess I didn't solve that, well, do the other two then :3
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    (Original post by Polpi)
    What if they give us gel electrophoresis.What would be the Dependent and independent variables for it?
    i was thinking and maybe they could give us something to do with cystic fibrous and use the chi squared test since its comparing results of observed and expected.
    the punnett square can be drawn for the genotype of the unborn baby.This would be expected.ALSO this would only be the case if one of the parent is affected and the other is a carrier or both are carriers.

    now we carry out the gel electrphoresis of the amniotic fluid obtained,the bands matching which parent will determine whether the baby is affected or not.
    lol this is just my own theory,prolly wont come up as we don't know anything about the other variables.
    Oops this seems to be a hard one! I hope this doesn't come up :/
    Well I was thinking about this so I guess these things would do but not really sure
    Dependent variable: The distance moved by a DNA fragment
    Independent variable: Length of DNA strands
    Standards:
    1) agarose density
    2) voltage
    3) buffer characteristics
    4) temperature (the chamber does get warmer during the run)
    5) time

    Umm, for control we'll probably write: Petri dish with gel and buffer but no DNA

    And I have an instinct that this might show up related to crime scene and all.
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    (Original post by user179)
    Oh, Thank you
    No problem Best of luck ^_^
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    (Original post by Aimen.)
    Oops this seems to be a hard one! I hope this doesn't come up :/
    Well I was thinking about this so I guess these things would do but not really sure
    Dependent variable: The distance moved by a DNA fragment
    Independent variable: Length of DNA strands
    Standards:
    1) agarose density
    2) voltage
    3) buffer characteristics
    4) temperature (the chamber does get warmer during the run)
    5) time

    Umm, for control we'll probably write: Petri dish with gel and buffer but no DNA

    And I have an instinct that this might show up related to crime scene and all.

    This may come up!
    But the control for this experiment can be done by something called a "standard DNA ladder", its basically a DNA whose features are well known to the scientists and hence they use it to compare the other DNA strands with it. But "No DNA" could work as well I guess..
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    Name:  20160511_203147-1.jpg
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    Does this seem reasonable for Q#1?
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    (Original post by Sandy_Vega30)
    A DNA strand consists of many genes that code for specific amino acids right?
    So the scientist decided to examine ONLY 5 genes that are different from each other.
    I hope that makes sense.
    Okay this seems perfectly right ! Thanks again
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    Hey guys! Can anyone explain to me why we need to control temperature in the tensile strength of fibers experiment? As in what is the effect of temperature on tensile strength of fibers?
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    (Original post by Aimen.)
    Name:  20160511_203147-1.jpg
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    Does this seem reasonable for Q#1?
    Hey I think you first have to mix your DNA sample with restriction enzyme so the DNA sample is cut into fragments. I think you add the DNA fragments to the wells, not whole DNA samples. Makes sense?
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    Also, What is the dependent and independent variables of the Mitosis experiment?
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    (Original post by Polpi)
    What if they give us gel electrophoresis.What would be the Dependent and independent variables for it?
    i was thinking and maybe they could give us something to do with cystic fibrous and use the chi squared test since its comparing results of observed and expected.
    the punnett square can be drawn for the genotype of the unborn baby.This would be expected.ALSO this would only be the case if one of the parent is affected and the other is a carrier or both are carriers.

    now we carry out the gel electrphoresis of the amniotic fluid obtained,the bands matching which parent will determine whether the baby is affected or not.
    lol this is just my own theory,prolly wont come up as we don't know anything about the other variables.
    I guess if they would gives us gel electrophoresis, they won't include CF, they will more ask us that two people were suspects in a crime, their DNA was amplified by PCR, how will GE will show us which one of the two suspects is more likely to be the criminal, plan an investigation.......

    The dependent variable would be the size of DNA bands
    The independent variable would be DNA sample from suspect used

    But I am just guessing
    Spoiler:
    Show
    I hope you won't be an examiner one day, you would kill us
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    (Original post by Sandy_Vega30)
    Hey guys! Can anyone explain to me why we need to control temperature in the tensile strength of fibers experiment? As in what is the effect of temperature on tensile strength of fibers?
    If temperature is greater tensile strength would be smaller. It would be easier to break/tear the fibre at higher temperature..reason is not known but could u think of one? I guess bonds holding the cells together become weaker at high temperatures
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    (Original post by Sandy_Vega30)
    Also, What is the dependent and independent variables of the Mitosis experiment?
    Depends on situation.. Indep variable could be type pf tissue/cell for e.g. Root or stem or watever(young tissue or old)
    Dep variable would be rate of mitosis
 
 
 
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