[iesians]

(Original post by Abrar_Higuain)
u are an angel my friend!!!!! God bless you!!!!!!!!!!!!!

lol ! just make dua for me Abrar that i get A in this ..!

[Abrar_Higuain]

(Original post by iesians)
lol ! just make dua for me Abrar that i get A in this ..!

FIAMANILLAH......I pray that u get 60/60 in unit 6 and if u have da entire A2 then u get 300/300.....just pray for me so that i can manage a 240/300 to ensure an A...coz i only have 5 marks lead in AS.....

[iesians]

(Original post by Abrar_Higuain)
FIAMANILLAH......I pray that u get 60/60 in unit 6 and if u have da entire A2 then u get 300/300.....just pray for me so that i can manage a 240/300 to ensure an A...coz i only have 5 marks lead in AS.....

INSHALLAH !!! just work very hard ! and ill give a tip from experience .....answer what is required !! seriously this is the most cherished tip !! in unit 2 i used to write whatever i knew without knowing the demands of the question and i got a B !! in unit 4 i was very precise and i only answered in two sentences but i answered what the question asked i got ALHAMDULLILAH 114/120 !

[iesians]

if gel electrophoresis comes what will be the dependant and independant variables ..?!

i reckon :-
dependant :- distance travelled by DNA fragments
independant :- size of the DNA fragment

what to do you guys think ?

[gcse_____]

(Original post by iesians)
if gel electrophoresis comes what will be the dependant and independant variables ..?!

i reckon :-
dependant :- distance travelled by DNA fragments
independant :- size of the DNA fragment

what to do you guys think ?

the independent I think it's more appropriate to write length of DNA fragment instead of its size as DNA fragments migrate according to length as mentioned on pg79 in the a-level book on the diagram.(Shorter fragments move faster than longer ones)

And for the dependent variable why do we choose the distance

[Nukpp]

(Original post by iesians)
for preliminary :-
-practice the method beforehand to actually see if it will work or not
-write the independent variables which can affect the dependant variable
-state how you wil control them
-find out favourable conditions for the experiment and try to impose them in the actual experiment
-select a suitable timescale to measure the dependant variable.
(note ive written dependant variable ....in the real exam replace it with the dependant variable asked in the exam eg:- number of egg hatched , human height etc....)

then theres always a question on ethical issues and safety :-

-(if about animal) top notch veterinary services cannot be provided
- do not put too much stress or it may die
- relocate to natural environment soon after the experiment is over
- keep lab conditions hygeinic

-(if about plants) wear gloves
- careful of insect biting
- do not tamper with other plants
- try not to stamp on other plants
- plants may be poisonous

and safety:-
- wear gloves
-wear goggles
-clean benches with ethanol
- flame necks of bottles to avoid air borne contamination
- possible chances of bacterial infection
- some people maybe allergic to certain chemicals used during the experiment.

......................for the 10 mark question basically write whatever you can think of , its 2 pages , fill them completely !!!!!!

Limitations :-

- not possible to control all factors affecting dependent variable
- conditions in lab may differ from conditions in the natural environment
- (then become specific) eg :- cloud shade affecting sunlight reaching earth , not placing the cotton wool in same place between eye stalks , not able to keep temperature constant , impossible to control genetic variations in seeds and organisms , difficulty in counting all the eggs through the microscope ....etc etc etc !!!

Hope this helps ...!

thank you so muchhhhh!!!!!!!

[d_94]

I hope gel electrophoresis comes! I love that exp.
God. I'm freakin' nervous right now.

3 days to go!! Aghhhhhhhhh

[iesians]

(Original post by d_94)
I hope gel electrophoresis comes! I love that exp.
God. I'm freakin' nervous right now.

3 days to go!! Aghhhhhhhhh

ikr !!! i want snail habituation to come !! its so easy !!!
im freaking out too !!!!! lets hope for the best

[iesians]

when we draw a scatter graph do we make a line joining all the points or do we draw a line of best fit ! and a line of best fit is the one which is straight and doesnt necessarily touch all the points ? right ?

[Abrar_Higuain]

(Original post by iesians)
when we draw a scatter graph do we make a line joining all the points or do we draw a line of best fit ! and a line of best fit is the one which is straight and doesnt necessarily touch all the points ? right ?

My teacher told me not to draw a line..just plot the points and make examiner understand that they r correctly plotted....making a SCATTER graph

[iesians]

(Original post by Abrar_Higuain)
My teacher told me not to draw a line..just plot the points and make examiner understand that they r correctly plotted....making a SCATTER graph

well i thought of that ........but look what i found in a markscheme :-

A Correctly orientated and labelled axes;
S Scale correct and suitable size (more than ½ graph paper)
P Plot all points correctly;
F Format correct, should be scatter graph with good attempt at line of
best fit;


...........thats why im confused ...!

[iesians]

(Original post by gcse_____)


the independent I think it's more appropriate to write length of DNA fragment instead of its size as DNA fragments migrate according to length as mentioned on pg79 in the a-level book on the diagram.(Shorter fragments move faster than longer ones)

And for the dependent variable why do we choose the distance

i chose distance because that depends on the length of DNA fragment. i mean if length is longer then distance travelled would be smaller and vice versa ...so.......... what do you reckon ?

[behzad11]

(Original post by iesians)
well i thought of that ........but look what i found in a markscheme :-

A Correctly orientated and labelled axes;
S Scale correct and suitable size (more than ½ graph paper)
P Plot all points correctly;
F Format correct, should be scatter graph with good attempt at line of
best fit;


...........thats why im confused ...!

its OK if u draw a graph , whats more important is plotting the points ... scattering them is mentioned in the mark scheme ... well as far as i have seen , its mentioned in all mark schemes ...

[behzad11]

i think the sampling and all that is the worst thing that could ever happen to me ... mann , unit 6 for phy and chem isnt as hard as biology ... wtf is this ? lol

[k121op]

Universal Rule for Q3(10 mark one!!)
1)Identify the DV,i.e. exactly what u r measuring
2)" " IV,i.e. the factor u r altering to see its effect on DV
3)Ref to how u will alter and measure the IV,e.g using certain equipments,such as ph Meter to measure ph of a soln,light meter to measure light intensity,thermometer to measure temp,hydrometer to measure salinity,etc
4)Ref to how u will measure the DV at end of expt,e.g. mass loss can be measured using top-pan balance,increase in shoot length can be measured using a calibrated scale,etc.,ecological sampling techniques,etc.
5)ref to timescale/time period,e.g. how long the investg. will run,at what time will u carry it out,etc.
6)Identify at least 2 other variables that may affect ur DV
7)Steps to control these 2 variables mentioned.
8)Clear ref to repeats
QWC-2 marks

I'm very poor at ecological sampling...pls help me at this topic,e.g. when to choose random sampling/systematic sampling.Which statistical tests should i choose to take,e.g.when to do a t-test,when Spearman's Rank correlation test,and what's this Mann-Whittney U test as welll as Chi-squared test??Anyone??

btw,hope my points help u out in ur exam,if there's any mistake/addn...pls inform me!!

[iesians]

(Original post by k121op)
Universal Rule for Q3(10 mark one!!)
1)Identify the DV,i.e. exactly what u r measuring
2)" " IV,i.e. the factor u r altering to see its effect on DV
3)Ref to how u will alter and measure the IV,e.g using certain equipments,such as ph Meter to measure ph of a soln,light meter to measure light intensity,thermometer to measure temp,hydrometer to measure salinity,etc
4)Ref to how u will measure the DV at end of expt,e.g. mass loss can be measured using top-pan balance,increase in shoot length can be measured using a calibrated scale,etc.,ecological sampling techniques,etc.
5)ref to timescale/time period,e.g. how long the investg. will run,at what time will u carry it out,etc.
6)Identify at least 2 other variables that may affect ur DV
7)Steps to control these 2 variables mentioned.
8)Clear ref to repeats
QWC-2 marks

I'm very poor at ecological sampling...pls help me at this topic,e.g. when to choose random sampling/systematic sampling.Which statistical tests should i choose to take,e.g.when to do a t-test,when Spearman's Rank correlation test,and what's this Mann-Whittney U test as welll as Chi-squared test??Anyone??

btw,hope my points help u out in ur exam,if there's any mistake/addn...pls inform me!!

ok so here we go....
random sampling :- when land is even and doesnt show a change in its edaphic trend
systematic :- when land in uneven or shows a gradual change in topography or water content or vegetation etc.....

mann whitney isnt needed it was in old syllabus
T test is used to verify the null hypothesis , they will give the value of t , just see if this value is bigger than the value given in table at 0.05 level or not ! if its bigger then say we can reject null hypothesis and write down the alternative hypothesis , if smaller then vice versa.

Spearmans rank test is for finding out correlation ! positive , negative or none !

when to use what :0
if they give a lot of values for independant variable eg:- soil water content of 10 areas! . then use spearman test

if independant variables are two or three such as land with vegetation vs land without vegetation , then use t test !

[k121op]

do we have to calc critical values and stuff like significance values,and how do u plot the error bars...it's so complicated.First,u need to calc the variance,then SD,then SE,and then plot the error bars.Better stick to range bars instead!what say?And wish me luck in tomorrow's exam(BIO Unit 1)-1st time sitting!!

[d_94]

(Original post by k121op)
do we have to calc critical values and stuff like significance values,and how do u plot the error bars...it's so complicated.First,u need to calc the variance,then SD,then SE,and then plot the error bars.Better stick to range bars instead!what say?And wish me luck in tomorrow's exam(BIO Unit 1)-1st time sitting!!

No you don't have to caculate the critical values; it will all be given in a table.
Wish you the best tomorrow

[d_94]

inshAllah we'll all get great marks in the exam

[aqua05]

(Original post by iesians)
OMG loved it !! thank you so much !! i wish you were in my school !!!! what do you reckon will come ..? daphnia came in unit 3 now , so ithink theres quite a chance for vitamin C this time , i hate that practical !!!!!!

the vitamin C exp came in unit 3 in jan..dont think that would come