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edexcel biology unit 2 and 3b

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Reply 60

MarshmallowBob

hahah ow god i am sooo scared! ahhhh! lol.

Reply 61

demdil

Original post by MarshmallowBob

hahah ow god i am sooo scared! ahhhh! lol.

i am really scared, i only solved may 2009 !!!

Reply 62

MarshmallowBob

Original post by demdil

i am really scared, i only solved may 2009 !!!

I've solved all the pastpapers, and IM STILL SCARED!! lol.i finished them 3 weeks ago. and i cant recall anything :s-smilie:

Reply 63

demdil

Original post by MarshmallowBob

I've solved all the pastpapers, and IM STILL SCARED!! lol.i finished them 3 weeks ago. and i cant recall anything :s-smilie:

once they give you questions tomorrow, you will start to remember everything :smile:

i always feel like i dont remember anything before the exam, but during the exam it all comes back to me :biggrin:

Reply 64

verdikt

Here are some external resources I found for mitosis + totipotency. Enjoy:
http://www.nuffieldfoundation.org/practical-biology/investigating-mitosis-allium-root-tip-squash

https://docs.google.com/viewer?a=v&q=cache:3mnWF4zk5RYJ:www.saps.org.uk/attachments/article/289/SAPS%2520-%2520Student%2520Sheet%252012%2520-%2520Fast%2520tissue%2520culture.pdf+&hl=en&pid=bl&srcid=ADGEESh5xhdfeEUbnWmGoIFTk8e_UX1rlWFehHoq_u6eqvuPxf2ijYTiTFWmhRE2zugjKMkzLGuNYeAKlThQReakG2MBQM5gYZevOgzC3BZxT2AsckjqIyFnWAKVjcZwJpIm0pdw5iZH&sig=AHIEtbQctfEnBixux5lo4BTnCr2wTuJ0Kw

Reply 65

shahlakh

Original post by verdikt

hey thanks buddy! :smile:

Reply 66

demdil

Original post by verdikt

thank youu .. btw, i hope they ask about totiopotency and observing mitosis tomorrow!!!!

Reply 67

shahlakh

Original post by demdil

thank youu .. btw, i hope they ask about totiopotency and observing mitosis tomorrow!!!!

yeah pal seriously........... i also wish. do u think they will repeat any of the experiments that have previously come?

Reply 68

demdil

Original post by shahlakh

yeah pal seriously........... i also wish. do u think they will repeat any of the experiments that have previously come?

they might ask from the experiments that came before, but they will have to change a lot and i dont know how they can change the beetroot experiment for instance. and if they dont change, and ask (eg beetroot) then the exam would be like the one in 2009 :O so either way is good :smile:

they will either ask from what we solved through the past papers or they will ask totiopotency and observing mitosis. İ believe they will ask something they didnt ask before. or could be daphnia because it was in sample assesment, so doesnt really count as "came in the exam before".. dont know .. hope we all do well :smile:

Reply 69

shahlakh

Original post by demdil

yeah and as one guy stated here that what will the students of june 2013 do if all the experiments would have come up???

Reply 70

demdil

Original post by shahlakh

yeah and as one guy stated here that what will the students of june 2013 do if all the experiments would have come up???

they will change the sylabus :P joking.. i dont know. i only hope that they ask totiopotency and observing mitosis..

Reply 71

verdikt

Original post by demdil

they will change the sylabus :P joking.. i dont know. i only hope that they ask totiopotency and observing mitosis..

One of my teachers said they just might and she was dead on sure that either of the two will come. But trust no one! I don't want some flame war going on if it does really come now :P

Reply 72

mrperfect

Hey guys: Why is Hydrochloric acid added to the root tip when observing mitosis?

Reply 73

demdil

Original post by mrperfect

Hey guys: Why is Hydrochloric acid added to the root tip when observing mitosis?

as far as i know, it is to break the middle lamella and separate cells from each other so that they are in single layer and not on the top of each other..

Reply 74

verdikt

Original post by mrperfect

Hey guys: Why is Hydrochloric acid added to the root tip when observing mitosis?

To soften the tissues :smile:

Reply 75

mrperfect

Thanks to those who answered. How can I make the root tip experiment safer and more accurate?

Reply 76

ro0ro0

Original post by mrperfect

Thanks to those who answered. How can I make the root tip experiment safer and more accurate?

safer by wearing eye goggle when handling the acid and stain

Reply 77

verdikt

Original post by mrperfect

Thanks to those who answered. How can I make the root tip experiment safer and more accurate?

Goggles, gloves are the main keypoints. Also take care when cutting.

I heard something about not adding excess stain to it. Is this a safety measure and if so, can anyone explain why?

Reply 78

DevilSmite

Original post by mrperfect

Thanks to those who answered. How can I make the root tip experiment safer and more accurate?

Use gloves when dealing with HCL or orcein
If your using orcein as your stain, make sure to avoid skin contact cuz its corrosive and highly flammable. Wear eye protection(safety goggles)
and to improve accuracy, first thing that comes to mind is repeat the experiment a few times using the same vol of HCL,stain etc, same length of root, eg:5mm
u cud even repeat it using a different root tip like broad bean.

all the best man, even im pretty nervous, im just memorising all the experiments from the CGP book and doing the past papers from june 09 to jan 12, hope it all works out. Also I asked my teacher what might come in ques 2, u know that article thing, he told me to learn the lifestyle and risk factors(heart disease and stuff) and clinical trial, Obviously im not depending on that, but he's been right before so who knows :P

Reply 79

DevilSmite

Original post by verdikt

Goggles, gloves are the main keypoints. Also take care when cutting.

I heard something about not adding excess stain to it. Is this a safety measure and if so, can anyone explain why?

adding excess stain comes under precaution. Normally you add stain to darken the chromosomes in the root so mitosis can be observed more clearly, so adding too much stain might make the chromosomes even darker which wud make it difficult to observe mitosis...