*Biology Paper 5 tips*

[Dania_Yz]

not needed

Ok thank youu umm there's this q about the chi squared test on/11/53 b) (iii) I'm not being able to solve it can you clear for me how they got the expected value?

 

[Moi]

PP52
Winter 12
Q 2 - B iii

Which row do we use?
0.05 or 0.01 Probability

The T test shows the difference is Significant.

And the marking scheme states that we need to use row 0.05 Probabilty.... But why??
Doesn't o.o5 mean its Insignificant and due to chance??

 

[baqer mohammed]

Salmu alakom guyz ,
In question 3 O/N2007 P5 ,
how to calculate the expected result for the chi square ???
I really don't know how did they calculate it and have got 80 !! + how did they get the degrees of freedom = 2 ??? wont it be 1 ???

Here is the paper :
http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_w07_qp_5.pdf

and here is the MS :
http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_w07_ms_5.pdf


Waiting for your help

 

[baqer mohammed]

Salmu alakom guyz ,
In question 3 O/N2007 P5 ,
how to calculate the expected result for the chi square ???
I really don't know how did they calculate it and have got 80 !! + how did they get the degrees of freedom = 2 ??? wont it be 1 ???

Here is the paper :
http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_w07_qp_5.pdf

and here is the MS :
http://papers.xtremepapers.com/CIE/...and AS Level/Biology (9700)/9700_w07_ms_5.pdf


Waiting for your help

 

[Zarif009]

They reject serial dilutios? I dont think so.


heat screen/heat filter.

incubator

What's a heat screen? never heard of one

And thanks!

 

[Moi]

Salmu alakom guyz ,
In question 3 O/N2007 P5 ,
how to calculate the expected result for the chi square ???
I really don't know how did they calculate it and have got 80 !! + how did they get the degrees of freedom = 2 ??? wont it be 1 ???

Here is the paper :
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_qp_5.pdf

and here is the MS :
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w07_ms_5.pdf


Waiting for your help

Salmu Alaikom !

For the expected results:
Add the values and divide by the number of values
So (36+90+114)/ 3 = 80 (It's like taking the mean)

The Degrees of Freedom = No. of classes (objects) we are testing Minus 1 (n-1)
We are testing three classes, grazed for two years, ungrazed for 10 years, ungrazed for 30.
These are three things to test
using the formula n-1 -----> 3-1 = 2
2 is the degrees of freedom

Hope it helped

 

[1357911]

What's a heat screen? never heard of one

And thanks!

They havent mentioned in detail. They have only mentioned this word. An additional point which may help u to score.

My pleasure.

 

[BeBeskii108]

you should always write in the null hypothesis that the differences are not significant. That's what the null hypothesis is defined by

Ok thanks.

 

[BeBeskii108]

Good luck to all of you for your tomorrow's paper 5

 

[goodluckayesha]

View attachment 41579
mayjune 2010 paper 52 question1 (c) i
how to do this?

theres a hint in the question itself c the units and do ull get the answer

 

[Malik777]

Hey! I am not getting more than 19 marks in P5

 

[Dania_Yz]

here's this q about the chi squared test on/11/53 b) (iii) I'm not being able to solve it can you clear for me how they got the expected value?

 

[sitooon]

They reject serial dilutios? I dont think so.


heat screen/heat filter.

incubator

Some times they Reject waterbath and use room temp,
and in other cases Reject room temp, and use waterbath !
how to know this ?

 

[1357911]

Some times they Reject waterbath and use room temp,
and in other cases Reject room temp, and use waterbath !
how to know this ?

Depends upon the type of the experiment and the type of question asked .

 

[sitooon]

Can you say on what conditions will we use the two

 

[Malik777]

Can anyone tell me the difference between reliability and Validity ? :S

 

[shafayat]

Can anyone tell me the difference between reliability and Validity ? :S

validity depends on the type of test. chi-squared or t-test
reliability depends on the number of times the test is conducted
and accuracy depends on instrumentation used during the exp. :')

hope it helps

 

[Alool]

here's this q about the chi squared test on/11/53 b) (iii) I'm not being able to solve it can you clear for me how they got the expected value?

They have said in the question that the cats without tails are always heterozygous.. so in cross 1: both parents are heterozygous..
and since the allele without tail is dominant, then each parent has the alleles Rr ..
when both are crossed: Rr x Rr
offsprings will be RR, Rr, Rr, rr
so there is 3/4 chance that the offspring is without a tail..
therefore (3/4) * 112 = 84
112 is the total number of osprings
and there is 1/4 chance that the offspring has tail
(1/4) * 112 = 28
then continue the calculation to find chi square

 

[shafayat]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Biology (9700)/9700_w10_qp_53.pdf

In question no. 1 part c(iii)

why are we not multiplying the standard error with 2 when drawing the graph i.e why not drawing the error bars +-2(1x2) and +-4(2x2)?

I think when teachers say 2 Standard error units above and below. by that they mean
one above and one below total making two...

cuz I didnt find any other Explanation

 

[Alool]

null hypothesis means there is 'NO SIGNIFICANT DIFFERENCE' always.. there is no question of significant or not, cuz its always not...

umm it is more like stating the opposite of the statement