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Edexcel 6BIO7/01 (International Unit 3B) ~ 7th May 2013 ~ AS Biology

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GUYS FOR THE MITOSIS EXPERIENCE! Putting root tips into watch glass containing approx. 2cm3 of alcohol for a minimum of 12 hours. Ín the Scribd As Biology core practicals, its 12 min. what is right?
Original post by gimme those exams
GUYS FOR THE MITOSIS EXPERIENCE! Putting root tips into watch glass containing approx. 2cm3 of alcohol for a minimum of 12 hours. Ín the Scribd As Biology core practicals, its 12 min. what is right?


It should be mts. Not hours.

Posted from TSR Mobile
1) Cut final 5mm of a root tip from a plant such as an onion - This is where mitosis occur in a root
2) Add stain (orcein ) and acid - To highlight the chromosomes and acid to soften the tissues
3) Gently break open on a microscope slide and squash carefully - To spread out the cells so the layer is only one cell thick for ease of viewing
4) Add more stain and warm then look at slide on a microscope - Warm is to intensify the stain
5) some safety points: -Care when cutting
- Eye and skin care with acid and stain, so wear goggles ad gloves

Relaxedexams is this procees gd? enough?
Reply 443
Avatar for fadyfox95
fadyfox95
guys I use pencil to plot the graph and labeling it.is this correct and there is no scanning issue
Original post by thextractor007
Select the subject and click on marking scheme then

http://www.edexcel.com/quals/gce/gce08/Pages/default.aspx


they r asking to log in ..
can someone plz give me ms for 2013 bio unit 3 plz my exam is tmrw plz
Reply 445
Avatar for SKK94
SKK94
1
Original post by aishahsiddiqi
how do you plot the standard deviation? I'm doing the jan 2012 paper and i dont know how to include st deviations :s-smilie:


[btw This was explained previously in the thread]

First, draw a normal line graph.
Next, you have to do this for each point, I'll explain it for the first one (at 20oC)
- the s.d value is 0.09
- count up by 0.09 from 4.1 and draw a short horizontal line
- count down by 0.09 from 4.1 and draw another short horizontal line
- connect both of these lines with a vertical line
- this will now resemble the capital letter "I"
(you have to use the scale of the y-axis when plotting the sd values)

Here's is an example of the graph you are talking about (taken from the examiner report)
d.jpg

:smile:
Reply 446
Avatar for SKK94
SKK94
1
Original post by fadyfox95
guys I use pencil to plot the graph and labeling it.is this correct and there is no scanning issue


Yeah, it's fine. :smile:
The question papers state that you need an "HB pencil"
Make sure it is dark enough before submitting your paper.
Make sure there are no 'double lines' in your graph.
Draw single, clear lines.

I prefer to label the scales in pen. I think it should be fine either way?
Original post by Daniel Atieh
1) Cut final 5mm of a root tip from a plant such as an onion - This is where mitosis occur in a root
2) Add stain (orcein ) and acid - To highlight the chromosomes and acid to soften the tissues
3) Gently break open on a microscope slide and squash carefully - To spread out the cells so the layer is only one cell thick for ease of viewing
4) Add more stain and warm then look at slide on a microscope - Warm is to intensify the stain
5) some safety points: -Care when cutting
- Eye and skin care with acid and stain, so wear goggles ad gloves

Relaxedexams is this procees gd? enough?


I think there are different methods. My method:
1.) Cut 1-2 cm root tips
2.) Place roottips into watchglass with 2cm3 of acetic alcohol for 12 min
3.) Then add roottips into 5cm3 of distilled water for 4-5 min
4.) Dry tips on filter paper
5.) Add tips into watchglass containing pre-heated 2cm3 of Hydrochloric Acid
6.) Transfer one tip to microscope slide using sterile forceps(watch out: tip is fragile)
7.) Cut 4-5mm of growing area of tip
8.) Break open using sterile mounted needle and add drop of ethanoic stain and leave for 2 min
9.) add coverslip and blot firmly using tissue to squash root cells
10.) Observe under microscope, 400x resolution

Too detailed I guess`??
Reply 448
Avatar for SKK94
SKK94
1
Original post by sarahjehovah
they r asking to log in ..
can someone plz give me ms for 2013 bio unit 3 plz my exam is tmrw plz


Get them from here

https://www.xtremepapers.com/community/threads/edexcel-january-2013-question-papers-all-gce.23183/

(Qp was too large to upload)
6BI07_01_rms_20130307.pdf125.5KB
SKK94 is my mitosis experiment enough to gain 5 marks if they asked to?
Reply 450
Avatar for fadyfox95
fadyfox95
can I start the x axis by not using zero.for example starting x axis from 60, is this correct???
Reply 451
Avatar for kevsamuel
kevsamuel
Original post by daniya12
Yeah it would depend on the question and the context they out it in. The actual 'observing mitosis' core practical has no control, independant variables per se, but they could easily put it in a context where there would be independant variables. Eg/ how temperature or conc of acid affects number of cells in a particular stage of mitosis? So obvs, there would be such variables in this case.

The exam will be based on an experiement similar to the core practicals but in a different context.


So if the independent variable is either conc of acid or temperature, then what would the control variable and dependant variable be?
Reply 452
Avatar for SKK94
SKK94
1
Original post by Daniel Atieh
SKK94 is my mitosis experiment enough to gain 5 marks if they asked to?


Generally it's fine- may earn about 4 though.
Better to mention that you count the number of cells in each stage of mitosis, when observing under the microscope.
Depends on the question really.

ok, I'm off!
Good Luck for tomorrow! :smile:
Why is a stain used in the mitosis experiment?

To highlight the cells so they cn be observed easily under a microscope?

Posted from TSR Mobile
Someone has a good, easy-going description of the totipotency experiment for a typical 5 mark question

•

gimme those exams
1) Take a few plant cells of one type, called an explant
2)Place on agar which has certain growth regulators added
3)Cells divide by mitosis to form a cluster of cells
4)Divide cluster and then place in container with agar
5)Add different growth regulators to above to the agar hich stimulates plant cells to differentiate into roots, stem and leaves etc

Reply 456
Avatar for elfajare
elfajare
G00D nIgTh GoOd LuCk !! tHe END....
Original post by Relaxedexams
Why is a stain used in the mitosis experiment?

To highlight the cells so they cn be observed easily under a microscope?

Posted from TSR Mobile

It's either Orcein
or Toluidine blue
:smile:
Reply 458
Avatar for kevsamuel
kevsamuel
How would you comment on the validity of something?
in bibliography.
referencing books:
> authors name(s) (family names and then initials)
>year of publication in brackets
>full title of book (underlined) , with edition no. if not first edition.
>publisher

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