Edexcel biology 2017 As level paper

How was the Edexcel Biology As level paper for you?

Edexcel Biology B

Heard you guys got a really harsh question on microscope resolution

had like half a minute to answer that question

What did you say?
Friend told me Qs
1)6 marker on the different things that contribute to the resolution of microscopes
2)4 marks on how to obtain magnification of a drawing compared to real cell using micrometer (eye piece graticule)
3)4 marks on how to make some root tip cells more visible under a microscope

1 is harsh id say
type of microscope, light and electron
electron wavelength is smaller and so gives higher resolution, less scatter
Prep of sample- how well it is prepared as freezing and other processes reduce resolution. artifacts etc
Low illumination or wrong angle id say, sample not thin enough
Very harsh, expect a little leniency there

2-for the second one you would just say m=image/ actual,measure image using ruler on drawing, take average of couple cells, find actual length from micrometer, be sure to measure the same way around ( length on both or width on both)
then calculate m.

3- squash root tip to get a fine layer of cells
use conc stain toluidine
wet cover slip to get better sticking together and less air bubbles
lay down at angle and try to minimise air bubbles, slide layer of air away as you do.

I agree with your three and one. But for the 1 i talked a lot about the trends and give many figures and percentage increase/decrease stuff. The question 2 was the one i ran out of time on but i managed to get something in on eyepiece graticule and magnification. The third i said the same stuff and also to use a paper towel to press down on the cover slip. (it was in the core practical instructions sheet) and I also named the acid i think i said hcl

Yes the paper towel and acid are right, that question is nice because there is more than 4 marks worth to say, there is like 6 marks to say and probably 6 marking points

I'm still really gutted about the eyepiece graticule thing. I had read over that core practical like 5 times but i skipped it to do the 6 pointer and when i came back to it i had time to put three lines in

What did you say? I`m in a2
Friend told me Qs
1)6 marker on the different things that contribute to the resolution of microscopes
2)4 marks on how to obtain magnification of a drawing compared to real cell using micrometer (eye piece graticule)
3)4 marks on how to make some root tip cells more visible under a microscope

1 is harsh id say
type of microscope, light and electron
electron wavelength is smaller and so gives higher resolution, less scatter
Prep of sample- how well it is prepared as freezing and other processes reduce resolution. artifacts etc
Low illumination or wrong angle id say, sample not thin enough
Very harsh, expect a little leniency there

2-for the second one you would just say m=image/ actual,measure image using ruler on drawing, take average of couple cells, find actual length from micrometer, be sure to measure the same way around ( length on both or width on both)
then calculate m.

3- squash root tip to get a fine layer of cells
use conc stain toluidine
wet cover slip to get better sticking together and less air bubbles
lay down at angle and try to minimise air bubbles, slide layer of air away as you do.

What spec is this for? Is it Biology A Salters-Nuffield?