OCR AS biology coursework planning exercise.

Watch
This discussion is closed.
nafan
Badges: 0
Rep:
?
#1
Report Thread starter 16 years ago
#1
hey, can anyone help me with this, i really need some help with this question:

"you are required to plan an invetigation to find out if there is a relationship between cell size & diffusion

(cells of agar made with sodium carbonate & containing phenopthalein (a ph indicator change colour when they are placed into a dilute acid. as the acid diffuses through the block, the ph changes & the pink colour of the indicator dissapears
your planning must be based on the assumption that you are provided with the following:
*blocks of agar
*a ph indicator (may be cut to size)
*supply of 2M hydrochloric
*your scools labs resouces


any help appreciated!!!
0
nafan
Badges: 0
Rep:
?
#2
Report Thread starter 16 years ago
#2
my teacher said there are some special things i need to put to get high grades but wont tell me what
any ideas??
0
LS.
Badges: 8
Rep:
?
#3
Report 16 years ago
#3
What exactly are you stuck on?
0
nafan
Badges: 0
Rep:
?
#4
Report Thread starter 16 years ago
#4
im wondering what i should write in my background section

& what exactly is the relationship between cell size & diffusion

im so terrible at biology
0
Dil
Badges: 0
Rep:
?
#5
Report 16 years ago
#5
(Original post by nafan)
im wondering what i should write in my background section

& what exactly is the relationship between cell size & diffusion

im so terrible at biology
small size means high surface area:volume ratio therefore rate of diffusion is also high and vice-versa
0
GH
Badges: 13
Rep:
?
#6
Report 16 years ago
#6
You can also probably do a rate equation as well.
0
nafan
Badges: 0
Rep:
?
#7
Report Thread starter 16 years ago
#7
:confused: whats a rate equation & how do i do one? please explain!
0
GH
Badges: 13
Rep:
?
#8
Report 16 years ago
#8
You have this coloured circular area, at the end of the experiment. Working out the area, then the volume. And you now have the gel matrix entrained substance, which can be worked out, if assuming homogenous mixture. And so you have a time result as well. Therefore you can find out the rate of diffusion [cm^3/min]
0
Da-Dapper
Badges: 0
#9
Report 16 years ago
#9
Is that for this year pratical exam for OCR AS Biology?
0
nafan
Badges: 0
Rep:
?
#10
Report Thread starter 16 years ago
#10
(Original post by Da-Dapper)
Is that for this year pratical exam for OCR AS Biology?
thats this years ocr planning cousework. the practical exam will be something slightly related to it.
0
nafan
Badges: 0
Rep:
?
#11
Report Thread starter 16 years ago
#11
any ideas about what to put for the risk assessment of agar jelly?
0
hihihihi
Badges: 0
Rep:
?
#12
Report 16 years ago
#12
lol im doing this one too

im unsure about safety, but something to do with the acid i suspect.
0
hotchilli
Badges: 0
#13
Report 16 years ago
#13
(Original post by nafan)
my teacher said there are some special things i need to put to get high grades but wont tell me what
any ideas??
to get the high grades you need to justify what you are going. for example you must say why you have decided to use the basic equipment and what can go wrong. also you must identify the independant variable ( the two conditions) and the dependent variable ( the rate of diffusion) you could also say what you could have done to make the experiment more reliable. to get reallllly high marks you must use scientific language and scientific context. to help you with this read past experiments in textbooks. when i did my coursework, i pretended i wrote the coursework as though i was writing a degree level document not AS.
hope this helps.
0
X
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Regarding Ofqual's most recent update, do you think you will be given a fair grade this summer?

Yes (268)
34.1%
No (518)
65.9%

Watched Threads

View All