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    i used t test. if u compare those with 0% ABA to those with differing [ABA]s then you've got your two groups with your two distinct means, and provided you have 7-30 concentrations i figured it was ok
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    hi rae, i understand about t test but can you tell me more abou t7-30 concentrations? t test is to see if 2 sets of results are similar enough isnt it? dont think chi square is very popular...
    are you sure we need to mention stats. test at all? is it in the mark scheme?

    also someone said ethanol is v. soluble in ABA but only slightly in water and no at all in propanone- surely ethanol is polar solvent?i dont think propanone works...

    please stop that argument by the way- its A2 planning we are discussing here...

    one more Question- i undetstand how to extract tomato juice with fresh tomato using blender etc, but how do you extract juice using DRY tomato?

    cheers everyone
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    a bit irrelevent now but for future reference- the royal botanical gardens and horticultural websites are very handy for pracs like germination.
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    (Original post by bethhop)
    a bit irrelevent now but for future reference- the royal botanical gardens and horticultural websites are very handy for pracs like germination.
    LOL excellent timing yeah!!
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    Ok guys, i havent a clue about all this stats tests ur talking about! we dont do them! were doing the microbiology option module you see! we did sumat to do with chi square in genetics but not much. do we really have to include these? if so will someone pls explain??

    oh and to a few threads above, yeh ABA is very soluble in ethanol which is polar solvent.
    Thanks for any help guys!
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    so do we use ethanol then????? i thought its either water or propanol! please someone explain.
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    no, you use either water or propanone. ethanol is not supplied. people are talking about the solubility of ABA in ethanol so you can make assumptions about its solubility in either a polar or non polar solvent.
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    hi, my dependent variables (those that u have to measure) are:
    - % germination
    - dry mass of cress seeds to determine growth

    However, I was 'hinted' by various people there maybe another dependent variable "missing" and or maybe there is "an aspect" missing from those variables above.

    Please could someone help me out?

    I'm not sure if its something to do with % germination not being that accurate??

    But I think it might be associated with me doing two experiments, one with tomato extract + water, and the other with tomato extract + propanone, could it be a dependent variable missing associated with these TWO experiments?? If so, what can it be ? and how can I measure it?
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    what is that T test for? it is used to compare two sets of data, but what 2 sets of data
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    (Original post by rae)
    no, you use either water or propanone. ethanol is not supplied. people are talking about the solubility of ABA in ethanol so you can make assumptions about its solubility in either a polar or non polar solvent.

    In the planning sheet it says you are to make the assumption that you are provided with polar and non polar solvents. This does not mean only water and proanone. They just gave us a hint as to what we 'could' use, in the paragraph beforehand.

    Why use water when the inhibitor which we know about is more soluble in ethanol? I think you should use the ethanol to extract the inhibitor. Also, because if you make the extract with water, are you not giving the seeds more water than you do when you make the extract made with propanone?
    Just waiting for results of some exps. will post on my findings.
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    no they WANT you to use Propanone and Water. The only thing u get to 'choose' are either dried or fresh tomatos. The actual planning exercise paper is poorly phrased, poorly structured, leading to confusion, and WAY TOO VAGUE!!

    P.S. I am certain because teachers have rung up the exam board to check on this.
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    use glass petry dishs with the propanone only (if u test with plain propanone to see if it has an effect (control like thing))

    i used plastic in my preliminary and it reacted with the petery dish ,

    i am gonna try and write most of mine up on sunday, when i do i will summarize what i put here.
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    yea it reacted with plastic pertri dish but it doesnt matter as we are NOT using propanone in the experiment. arent we, and water doesnt react with petri dish, so its fine

    i heard dried tomato is better coz it has more concentrated aba germination inhibitors, is that true? if so , then how do we extract it from dried tomatoes, has any one got detailed method of extraction?
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    if we are using propanone to extract the inhibitor, the inhibitor will be in with the propanone. So if u use too much propanone then it will react with the petry dish.


    Cut up tomato,
    crush using pestle and mortar,
    liquidise it in a liquidiser,
    add a little water,
    mix it up some more,
    filter out the in-soluble material,

    Left with water with inhibitors.
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    nobody is using propanone, it is non polar, and ABA is polar. unless you are investigating other germination inhibitors.
    can someone give me difinition of abbibition (cant spell)
    cheers
    i also need to know which 2 sets of result T test is testing. why t test?
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    Im abit confised as to what the independant variable should be (the thing you are changing). Should this be the solvent used to extract the inhibitor or the concentration of inhibitor used? Or is the something else and im completely missing the point.
    Yeh dried tomatoes are better. You need to crush them, put in the solvent, separate(using whatever method you want) and there you have it! Simple. And simple is good.
    anyone know anything about this stats thing? Personally i dnt think you need to include this...thats only cuz im clueless tho.
    Any help wud be appreciated guys.
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    hmm
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    is the reason why dry tomatoes better is becoz it has more concentrated germination inhibitors? why is dry ones so good?
    we are not using propanone in exp. anyway coz result is that they dont promote germination, so no point in saying what it does to petri dish etc
    apparently there is marks for mentioning stats. have you checked the mark scheme coz im not sure
    my dependent vairalbe is concentration of juice. WHAT ARE THE CONTROL VARIALBVES (ones you are keeping constant), apart from light, tempearature, volume of solution and time interval between measuring dry mass/root length?
    any other brill ideas?
    how are you guys measuring germination? counting the number of seeds germinated everyday? how do you plot them on a table? do you divide the number of seeds germinated by the total number of seeds in the petri dish, and do this everyday? how many days should i do this for?
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    Dont have the mark scheme. I think the inhibitor is more concentrated in dreid tomatoes because it has not been diluted by the moisture present in a fresh tomato. In the propanone exp in my prelim, the cress seeds germinated and grew. this means that the inhibitor musnt have been present in the extract made. im still all confused about what the independant variable should be. my controls are pretty much the same as urs really.apparaently the tomato stuff contains sugars and that so this may change the pH of the extract. maybe this has an effect on the germination of the cres seeds. oh what the heck! im clueless and still getting nowhere with this plan!
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    i was thinking exactly tyhe same thing about pH, but there isnt a way we could meaure pH though, unless we get a pH meter, but it is out of resources- ie school lab wont have one- i dont think
    independent is the one you can measure with... so for me it must be different concentration of juice. it cant be choice of solvent coz in prelimiary it shows that propanone doenst promote germination, so it must be something polar, so it must be diffenret conc. of the juice with polar solvent ie water
 
 
 

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