# Cells, Exchange and Transport - PAST PAPER QUESTION HELP

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#1
http://www.ocr.org.uk/Images/175432-...-transport.pdf

How do you work out surface area to volume ratio in question 2a, help!

Thank you!
1
4 years ago
#2
(Original post by rm_27)
http://www.ocr.org.uk/Images/175432-...-transport.pdf

How do you work out surface area to volume ratio in question 2a, help!

Thank you!
Wouldn't it just be 6:10 after you cancel them???
0
4 years ago
#3
It would be 0.6:1

SA : V

600 : 1000

Divide both by 1000 as it is sa TO vol ratio

0.6:1
0
#4
(Original post by CrazyFool229)
It would be 0.6:1

SA : V

600 : 1000

Divide both by 1000 as it is sa TO vol ratio

0.6:1
Hey, thanks so much for answering!! I still don't really get it, do you mind doing steps on how you worked each thing out? I've got an exam tomorrow so all help is greatly appreciated!!
0
4 years ago
#5
No problem
So you read off the table the SURFACE AREA and the VOLUME. It tells you to read the values for the 10mm length I believe (On my phone, sorry).

Now, surface area TO volume ratio means you always divide the SURFACE AREA by the VOLUME. As it is a ratio you always get something like this

SA : 1

Notice how the second number is 1? This is because every time you DIVIDE BOTH SIDES by the VOLUME, and dividing the same number by itself always equals 1.

So here's an example

A cube has a SURFACE AREA of 10cm^2
VOLUME of 5cm^3

Setup the equation so it is like this

SURFACE AREA : VOLUME

Now the SA(surface area) is 10cm^2 and the volume is 5cm^3 so it will look like this

10 : 5

Now you DIVIDE BOTH SIDES BY THE VOLUME

So 10÷5 is 2
5÷5 is 1

2:1

I have an exam too on AQA Bio AS. Good luck!
Posted from TSR Mobile
2
#6
[QUOTE=CrazyFool229;65182197]No problem
So you read off the table the SURFACE AREA and the VOLUME. It tells you to read the values for the 10mm length I believe (On my phone, sorry).

Now, surface area TO volume ratio means you always divide the SURFACE AREA by the VOLUME. As it is a ratio you always get something like this

SA : 1

Notice how the second number is 1? This is because every time you DIVIDE BOTH SIDES by the VOLUME, and dividing the same number by itself always equals 1.

So here's an example

A cube has a SURFACE AREA of 10cm^2
VOLUME of 5cm^3

Setup the equation so it is like this

SURFACE AREA : VOLUME

Now the SA(surface area) is 10cm^2 and the volume is 5cm^3 so it will look like this

10 : 5

Now you DIVIDE BOTH SIDES BY THE VOLUME

So 10÷5 is 2
5÷5 is 1

2:1

I have an exam too on AQA Bio AS. Good luck!
Posted from TSR Mobile[/QUOTE

THANK YOU!!! Good luck too!
0
4 years ago
#7
Where did you get that answer from? The mark scheme says it is 0.6:1 because

600:1000

600 divided by 1000 = 0.6
1000 divided by 1000 = 1

Hence ratio is 0.6:1

Posted from TSR Mobile
0
4 years ago
#8
yeah CrazyFool229 is correct, it is simply the SA divided by the Vol. The decimals may have confused you. 0.6:1
0
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