Biology P5

[MukeshG93]

Why M/J 07 no 1 iv) the mark scheme write plus minus 1Sm not 2Sm???

The Sm means the standard error, meaning the actual value may be errored by that much, either positively or negatively. So, it would be mean +- Sm. The 2Sm comes from the fact that the difference between m + Sm and m - Sm = 2Sm. Use mathematics people, just because this is biology does not mean you can ignore the good ol' numbers!

 

[zeebujha]

Why M/J 07 no 1 iv) the mark scheme write plus minus 1Sm not 2Sm???

The Sm means the standard error, meaning the actual value may be errored by that much, either positively or negatively. So, it would be mean +- Sm. The 2Sm comes from the fact that the difference between m + Sm and m - Sm = 2Sm. Use mathematics people, just because this is biology does not mean you can ignore the good ol' numbers!

the thing is the book quotes it as +-2Sm and this would result the range being 4SM

 

[MukeshG93]

For a respirometer, I'd recommend using a manometer with a moving dye indicator. It is more accurate as no air can pass through the dye at all whereas it may pass through in a gas syringe. It's all about accuracy and reliability and using the best suitable apparatus.

 

[MukeshG93]

For a respirometer, I'd recommend using a manometer with a moving dye indicator. It is more accurate as no air can pass through the dye at all whereas it may pass through in a gas syringe. It's all about accuracy and reliability and using the best suitable apparatus.

Speaking of which, cheap marks galore:

- The volume decrease is determined by measuring the distance moved by dye
- The actual volume is = l x (pi)r^2 where l is the distance moved by the dye and r is the radius of cross-section of the capillary tube (the gas syringe is already calibrated to give volume so there is no opportunity for marks here if you are speaking of using a gas syringe)

 

[MukeshG93]

POTOMETER ADDITIONAL PROTIP:

Cut the plant underwater to avoid air bubbles from entering the xylem vessels! Air bubbles block out the passage of water.

 

[zeena123]

Has anyone finished writing the paper?

 

[MukeshG93]

Ugh, could the questions get any more boring? What are you supposed to write in that sort of exam? I will surely get an A but it's not an A worth boasting about. I had prepared so well and worked my ass off for that? =_=

 

[zeebujha]

Can't think of any skill that I mentioned in the forum that came in handy!!!!!!!!!!

 

[zeebujha]

very boring and confusing paper!

 

[Newbie]

It happens .....

But who cares ... I think most of the people liked this paper overall .... I hope it went good for you too :Yahoo!: :Yahoo!:

 

[Salimsaid89]

This was a really weird paper 52..the 1st question required careful planning and thinking...very easy to make mistakes.Btw what do you guys think the threshold will be?