Urgent help require in p5!

[rodent123]

can anybody please give me a proper explanation regarding dependent variable and independent variable? and also how to identify them in an experiment in all chemistry physics and biology p5? can anybody also share some good tips and ideas on how to best tackle p5 for all three subjects? please help I am quiet weak in p5! i didn't get good grades in my practicals last year and i fear that p5 is kind of an practical paper so i might not fare good in it

 

[sweetiepie]

http://www.xtremepapers.com/community/threads/some-different-notes-website-are-available.10423/

 

[rodent123]

i can't find tips on paper 5!!! neither any information on dependent or independent variable! help people!

 

[XPFMember]

As-salam-o-alaikum wr wb!

in simple words...independent is the thing you are changing, and dependent is the thing which is being affected by the change u made...

eg u want to see the effect of temp on the rate of reaction....so u'll take different temp...in otherwords temp is what u r changing so it'll be the independent variable...and the rate is being affected by temperature..so it is the dependent variable!

 

[XPFMember]

As-salam-o-alykum!

Well, I think you should write in paragraph form

the points you shud include in 8 marks question like these:

-independent variable(s)
-dependent variable
-control variable(s) and how to control them
-procedure: how the apparatus will be used, etc.
-reliability,( must be atleast 3 repeats for each set of readings...)
-safety precaution (any 'one' required!)

(this is for biology)

 

[Doctor Nemo]

can anybody please give me a proper explanation regarding dependent variable and independent variable? and also how to identify them in an experiment in all chemistry physics and biology p5? can anybody also share some good tips and ideas on how to best tackle p5 for all three subjects? please help I am quiet weak in p5! i didn't get good grades in my practicals last year and i fear that p5 is kind of an practical paper so i might not fare good in it

The independent variable is the condition that you control and you vary and the dependent variable is the variable that you measure. That is it, there is nothing else to it and it doesn´t matter whether it is biology, chemistry or physics.

You plot the independent variable on the x-axis and the dependent variable on the y-axis.

The difficulty of paper 5 comes from the lack of predictability as to its content. You can be asked about experimental situations that you would not have encountered in your school laboratory. There is no way around it, the way to prepare for paper 5 is by doing the past papers. This is generally true but especially for paper 5. By doing the papers and then examining carefully the mark schemes you can see what is expected in your answers.

For example you are always asked to design an experiment. At times these questions are rather vague. By looking at the past papers you can see what type of answers are accepted, often you can get points by stating rather obvious things. You can get points by mentioning some safety precaution or by stating that to improve the reliability of the results by repeating the measurements.

Also by examining the past papers and their mark schemes you can see what are acceptable ways of making certain measurements such as the volume of gas produced in a reaction or how to prepare a saturated solution of a salt.

 

[rodent123]

Thanks Nemo and the moderator as well I guess can you also please clarify what si the difference between validity.accuracy and reliability and what should I write when asked for this?

 

[XPFMember]

assalamoalaikum wr wb!

Remember for accuracy, it's how accurate ur readings are...like u can measure up to a 0.1 or 0.01...and all that..
To increase the accuracy, u may use a different apparatus...which gives better readings..

for reliability, it's how many times u repeat...esp. for biology..u must say that repeat atleast THRICE! no less than that..and then average..

a common error is to say about repeating when they ask how to increase accuracy...so AVOID that! accuracy is abt the apparatus...reliability about how consistent ur readings are..

 

[Doctor Nemo]

Thanks Nemo and the moderator as well I guess can you also please clarify what si the difference between validity.accuracy and reliability and what should I write when asked for this?

Accuracy is the technical term for the level of uncertainty in the measurements. They are +/- 1% for example.

Validity and reliability are overall assessments of the correctness of the experimental procedures, the collection of the data and the methods used to evaluate the data. The Biology and Chemistry syllabuses mention the need for judging how reliable is the investigation and how much trust can be placed in its outcomes.

Generally you are being asked to evaluate the procedures for the sources of error and how the procedures could be improved to eliminate them. For example in measuring the rate of decomposition of varies carbonates you could suggest weighing them as a more reliable method then measuring the volume of carbon dioxide or in general collecting more data by doing more time points or repeating the experiments.