A2 Biol prac!Watch
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?
a bit irrelevent now but for future reference- the royal botanical gardens and horticultural websites are very handy for pracs like germination.
oh and to a few threads above, yeh ABA is very soluble in ethanol which is polar solvent.
Thanks for any help guys!
- % 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?
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.
P.S. I am certain because teachers have rung up the exam board to check on this.
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.
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?
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.
can someone give me difinition of abbibition (cant spell)
i also need to know which 2 sets of result T test is testing. why t test?
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.
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?
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