Edexcel IAL Biology Unit 5 (WBI05) Scientific Article Discussion - June 2016

UPDATE: I HAVE SCREENSHOTS WOOOO

However there's like over 50 of them and they're on my phone and omg gonna take forever to put on tsr.
If you want them can you like inbox me on fb? I'm literally so lazy pls
Search 'Anna Christophides' my profile picture is the same as my little avatar on here.
Whoever u are idm, just inbox me be like ''homie i want the screenshots'' and i'll share

UPDATE: I HAVE SCREENSHOTS WOOOO

However there's like over 50 of them and they're on my phone and omg gonna take forever to put on tsr.
If you want them can you like inbox me on fb? I'm literally so lazy pls
Search 'Anna Christophides' my profile picture is the same as my little avatar on here.
Whoever u are idm, just inbox me be like ''homie i want the screenshots'' and i'll share

UPDATE: I HAVE SCREENSHOTS WOOOO

However there's like over 50 of them and they're on my phone and omg gonna take forever to put on tsr.
If you want them can you like inbox me on fb? I'm literally so lazy pls
Search 'Anna Christophides' my profile picture is the same as my little avatar on here.
Whoever u are idm, just inbox me be like ''homie i want the screenshots'' and i'll share

Ahhh Thank you so much, it sounds like a great way of divising time, I will definitely start trying it!!! Normally,I used to solve the first question, spend around 20 minutes on it then jump to the last question the go back to the second so I guess I have to change it because it's consuming so much time!! And I am the kinda nervous one so like i'll keep rechecking till time finishes!!

By the way, on the question you have just posted before, I was solving this paper, for the table, the question didn't even say that we should calculate the mean so how i am supposed to know? (although I guess in the recent papers, they always specify when to calculate the mean)

Sorry for asking a lot

I'm a bit confused with validity??
Could anyone explain and give me a list of examples

Summary notes for unit 6 bc I haven't found the thread for it

when describing an experiment:
-state dependent and independent variable and state how to measure the independent (dcpip, counting, measuring length, etc)
-5 diff. values for dependent variable (e.g. temperature - 5, 10, 15, 20, 25 deg) and how to control (waterbath/incubator,etc)
-refer to REPEATS.
-try come up with a control
-state a variable to keep constant for validity (usually source of organism or pre-treatment, or fruit from same source)

writing null hypothesis:
-''no significant correlation between (dependent) and (independent) variable
OR
-''no significant difference between (dependent) and (independent) variable
-use correlation when comparing a range of values, use difference when comparing 2 diff values.

detailed method of experiment (same as describing PLUS these):
-mention time period (example: leave for 48 hours)
-2 variables to control and how to keep them constant (this gives 4 marks so MAKE SURE YOU DO IT)
-description eg. aseptic conditions

when it asks to record, present and analyse data:
-calculate the rate/growth/change
-calculate means
-draw table w/ headings and units
-sketch graph w/ headings and units
-say ''use spearmans rank to determine correlation''

I have a question tho if anyone knows the answer.
On some questions it says ''the student applied a t-test to explore significance blah blah blah, she obtained this result, the table below shows critical values for t-test calculations'' how the hell do u draw conclusions from that

Thank you very much!!!! And best of luck for your exams


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UPDATE: I HAVE SCREENSHOTS WOOOO

However there's like over 50 of them and they're on my phone and omg gonna take forever to put on tsr.
If you want them can you like inbox me on fb? I'm literally so lazy pls
Search 'Anna Christophides' my profile picture is the same as my little avatar on here.
Whoever u are idm, just inbox me be like ''homie i want the screenshots'' and i'll share

Thank you soooo much!
Let me try to answer your question though.
You usually use significance level 0.05 (I.e 95% confidence level) and then you compare the student calculated t value with the critical value at 0.05, and then draw out a conclusion from that. If the students calculated value is higher than the critical value then you accept that there is a correlation in the two variables that you're investigating. (Eg: There is a significant correlation between the increase in conc of rennin and the rate of milk clotting; if there is a null hypothesis stated then you reject it and you have to mention this in the ans as well aaaaand you can also state if there is a positive or a negative correlation) if the student's calculated value is lower than the critical value then you state that there is no significant correlation between blah blah and you accept the null hypothesis (state null hypothesis only if it was asked in the question before) if asked, you have to give the biological explanation as well.
Sometimes degrees of freedom is given and you have to choose in that case don't panic it's just the sample size.

0.05 is the probability and 95% is its percentage.

I hope it's clear to you now.

I'm afraid you are not supposed to use the word "correlation' when it comes to t'test.
The t-test is for finding whether there is a significant difference between two means.
Hence,you say, "There is or isn't a significant DIFFERENCE between..."

Hello,

So, do we only use the word 'correlation' for the Spearman's rank test then?

I have a question if anyone could help me the first question 1a is always describing the experiment, what are some standard answers you should put? I find it's different for every paper, I can't figure out the pattern.

Alright then

So, what are your predicitons for unit 6B guys?

To write an experiment, you must use CORMS.
C - control: always include a control in your experiment, eg for the light intensity leaf experiment have an empty test tube with just some indicator in it...
O - organism: what organisms will be involved and what similarities do they need to have eg. same sex, age, health, ect
R - repetition: how many repeats do you do to make it more practical?
M - measurement: what do you plan to measure? eg growth length temperature weight size ect.
S - standard: what do you need to keep the same? eg time, diet, oxygen, light intensities pH ect

There is no other pattern because all experiments are different. But in order to plan an experiment? Bottom line, Use CORMS.

What about urs? You predicted anything?

I have a question if anyone could help me the first question 1a is always describing the experiment, what are some standard answers you should put? I find it's different for every paper, I can't figure out the pattern.