• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Biology P5 Doubts, Guess Papers, Important Concepts and Leaks.

nimzy95

nimzy95

Messages
30
Reaction score
66
Points
8
Yeah sure, well c1 is the concentration of the original solution, the one that you are provided with , also know as the stock solution
M1 is the mass of solute in it , usually sucrose glucose whatever depending on the question
V1 is the volume of the stock solution that you are going to use . I think it's best to use 10cm3 . It is easier to make the dilutions with that as the total volume

C2 is the concentration of the solution that you want to make using the stock solution
M2 is the mass of the solute you will use for that dilution
V2 is the volume of the new solution that you are making , I.e 10cm3 too
Hope this helps
 
SanAntonioSpurs

SanAntonioSpurs

Messages
2
Reaction score
4
Points
1
AOA,

I wanted to ask about dilution techniques. Could someone please explain me the working behind how the marking scheme has been able to come up with the ratios in Q1 b) i) (November 2012/ 51)?
 

Attachments

  • 9700_w12_qp_51.pdf
    91 KB · Views: 11
  • 9700_w12_qp_51.pdf
    91 KB · Views: 3
nimzy95

nimzy95

Messages
30
Reaction score
66
Points
8
SanAntonioSpurs said:
AOA,

I wanted to ask about dilution techniques. Could someone please explain me the working behind how the marking scheme has been able to come up with the ratios in Q1 b) i) (November 2012/ 51)?
Click to expand...
It's like you have a stock solution of 4000mgdm-3 . You have to make 2000,1000,500,250
Do you see the trend ? You are basically taking half the preceding solution every time
So take 10cm3 of the 4000 in a test tube
Now for a dilution of 2000 take 5cm3 of the prev solution ( 4000) in this case, and add 5 cm3 of distilled water
Nest take 5cm3 of this solution and add 5 cm3 of water
This is a form of serial dilution in which you half the previous concentration every time by adding water
Hope this helps
 
J

JoHN_95

Messages
6
Reaction score
12
Points
11
nimzy95 said:
It's like you have a stock solution of 4000mgdm-3 . You have to make 2000,1000,500,250
Do you see the trend ? You are basically taking half the preceding solution every time
So take 10cm3 of the 4000 in a test tube
Now for a dilution of 2000 take 5cm3 of the prev solution ( 4000) in this case, and add 5 cm3 of distilled water
Nest take 5cm3 of this solution and add 5 cm3 of water
This is a form of serial dilution in which you half the previous concentration every time by adding water
Hope this helps
Click to expand...
nimzy95 said:
Yeah sure, well c1 is the concentration of the original solution, the one that you are provided with , also know as the stock solution
M1 is the mass of solute in it , usually sucrose glucose whatever depending on the question
V1 is the volume of the stock solution that you are going to use . I think it's best to use 10cm3 . It is easier to make the dilutions with that as the total volume

C2 is the concentration of the solution that you want to make using the stock solution
M2 is the mass of the solute you will use for that dilution
V2 is the volume of the new solution that you are making , I.e 10cm3 too
Hope this helps
Click to expand...
Thank you soo much...may all ur papers go bombstick n good luck x
 
SanAntonioSpurs

SanAntonioSpurs

Messages
2
Reaction score
4
Points
1
nimzy95 said:
It's like you have a stock solution of 4000mgdm-3 . You have to make 2000,1000,500,250
Do you see the trend ? You are basically taking half the preceding solution every time
So take 10cm3 of the 4000 in a test tube
Now for a dilution of 2000 take 5cm3 of the prev solution ( 4000) in this case, and add 5 cm3 of distilled water
Nest take 5cm3 of this solution and add 5 cm3 of water
This is a form of serial dilution in which you half the previous concentration every time by adding water
Hope this helps
Click to expand...
Thanks a lot! Now I do get it!;)
 
nimzy95

nimzy95

Messages
30
Reaction score
66
Points
8
SB29597 said:
For that, you need to find the standard error, given by standard deviation/ sq root of number of measurements. Plot that value as a bar over the main bar or point- try googling around for images- you'll immediately understand when you read this explanation with a picture.
Click to expand...
Umm hey , about the error bar , do we have to multiply the standard error by 2?
 
omarjaved619

omarjaved619

Messages
70
Reaction score
117
Points
18
Q1. The b(i) part has brought me down to my knees!

Ok. So our objective is to find the rate of movement of water. That is Distance moved/ Time taken. Now my confusion arises here. HOW DO WE FIND OUT HOW MUCH THE WATER HAS TRAVELLED?

The first part of the question talks about cutting the stem into sections and observing under a microscope to locate the water+dye containing tissue.

NOW, if we do the same thing with the plant, and find out water HAS NOT reached that point yet, our experiment is screwed.

So my question is, how do we find out the distance the dye has travelled? Thanks!
 

Attachments

  • 9700_s09_qp_5.pdf
    211.8 KB · Views: 5
nimzy95

nimzy95

Messages
30
Reaction score
66
Points
8
omarjaved619 said:
Q1. The b(i) part has brought me down to my knees!

Ok. So our objective is to find the rate of movement of water. That is Distance moved/ Time taken. Now my confusion arises here. HOW DO WE FIND OUT HOW MUCH THE WATER HAS TRAVELLED?

The first part of the question talks about cutting the stem into sections and observing under a microscope to locate the water+dye containing tissue.

NOW, if we do the same thing with the plant, and find out water HAS NOT reached that point yet, our experiment is screwed.

So my question is, how do we find out the distance the dye has travelled? Thanks!
Click to expand...
I think you can see the dye in the leaves since the veins are comparatively thinner .so you can record the time taken for the dye to reach the leaves? I am not that sure but I am guessing
 
SB29597

SB29597

Messages
259
Reaction score
192
Points
53
omarjaved619 said:
Q1. The b(i) part has brought me down to my knees!

Ok. So our objective is to find the rate of movement of water. That is Distance moved/ Time taken. Now my confusion arises here. HOW DO WE FIND OUT HOW MUCH THE WATER HAS TRAVELLED?

The first part of the question talks about cutting the stem into sections and observing under a microscope to locate the water+dye containing tissue.

NOW, if we do the same thing with the plant, and find out water HAS NOT reached that point yet, our experiment is screwed.

So my question is, how do we find out the distance the dye has travelled? Thanks!
Click to expand...

Heres a basic idea:

You take a stem, cut a section to show that no coloring or pigmentation exists. Then you mix dye in the water- preferably something like red or dark blue and let the samples be in water for 5, 10, 15, 20 min. Take three samples per time.

Find mean for all. You will be able to obtain values to plot a graph or whatever.
 
You must log in or register to reply here.
Top