AS SNAB Edexcel Biology

does anyone else have to write up practicals and tick off boxes on a sheet? Does anyone know what that's about and if it counts towards our grades?

also what is the acid/alcohol/ cold water for in the 'observing mitosis' practical for? My teacher said the acid is to break down the cell wall and the alcohol is to break down the membrane. the ice cold water pauses the whole process and cleans it. But the snab revision guide only says the acid is used to soften the cell. ????

What did your teachers say?

Reply 41

BooAlphie

Original post by thegreenchildren

does anyone else have to write up practicals and tick off boxes on a sheet? Does anyone know what that's about and if it counts towards our grades?

also what is the acid/alcohol/ cold water for in the 'observing mitosis' practical for? My teacher said the acid is to break down the cell wall and the alcohol is to break down the membrane. the ice cold water pauses the whole process and cleans it. But the snab revision guide only says the acid is used to soften the cell. ????

What did your teachers say?

On the practical sheet it says:

to see the chromosomes inside the cells the cells must be seperated into layers that are ideally one cell thick. Plants cells are glued together by a middle lamella of pectins. The acid will break down the pectins that hold the cells together.

so That's probably what the revision guide meant by soften - soften so that the cells can be spread.

I have no clue what the ice cold water is for though. I'd be interested in what other people say :s-smilie:

I hadn't even t hought about the role of the ice cold water but on the sheet it does say that the root tips will be fragile after adding the ice cold water and to be careful when blotting the tips afterwards or a ppt could form, if thats any help?

Reply 42

TravH

Original post by Hdizzle

hiya

is the conference any good do you know?

Yes, they've been doing the course for a few of years. Pretty intensive, but only costs £15 for a full day. And Guildford is v easy to get to

Reply 43

TravH

Original post by Hdizzle

hiya

is the conference any good do you know?

The examiner with the practicals CD is called Gary Skinner

Reply 44

Munir.M

Do you still have em? haha

Reply 45

Munir.M

Original post by Stryder402

ive got really good notes for unit 2 if anybody wants it

Have you still got them? May I have them it might be 3 years too late lol. :smile:

Reply 46

Ray.Inspiration

2

Hi all,
I am retaking my AS coursework. My teacher forced me to do it on the use of HPV vaccine to postpone cervical cancer. I find it very very difficult to research on it, my deadlines is in 2 days. I have done most of it but I thought if someone has an A/B grade example of this topic, would really help as I could to use it as a checklist.
Any help would be greatly appreciated.
Thanks in advance...

Reply 47

tobermoray