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A level Biology: Post your doubts here!

Noor Ahmad

Noor Ahmad

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knowitall10 said:
The ruler measurment is converted into micrometers or whatever the unit the question measures it in. and then apply the magnification formula:
Whatever you measured/ the actual = magnification. you know the magnification because you're using a microscope right? So if ur using x10 then put that in the formula and if ur using x40,then put that.
I hope i'm clear.
Click to expand...

Thank you so much. But i've got a question.
do we use the ruler to calibrate the eye piece graticule or do we directly measure the specimen using the ruler?
 
knowitall10

knowitall10

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dornam said:
Not really
Click to expand...
Ok...
C1= concentration provided
C2= concentration you want to make
V1= volume of the original solution u must use
V2= total volume of the solution (which you must keep constant)

C1V1=C2V2
According to the question, the total volume being kept constant is 10cm3
Your C1= o.1
V1= x
C2= 0.05
V2= 10
Now apply the formula.
0.1x= 0.05 x 10
x= 5
so you're taking out 5cm3 of the original solution and diluting it with (10-5 =5) 5cm3 water.
Now, try the table yourself. I explained what they did in the question. Tell me if u still don't get it.
You should make your own concentrations, a minimum of 5.
 
knowitall10

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Noor Ahmad said:
Vertical transmission,is the inheritance of genetic material,from parents to offsprings.
Horizontal transmission is the transfer of genetic material (Plasmids) from one bacterium to another.
Click to expand...
Yes. But both of them can be the transfer of plasmids.
 
knowitall10

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I don't really know man...practicals was never really my thing...
I'm sorry i can't help.....i'm having a very bad day.............................
 
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strangerss

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dornam said:
Can you help me with this one? If I have 6.25 cm^3 of 10% solution, and I mix it with 3.75 cm^3 of water, what will be the concentration of the solution?
Click to expand...
Use this formula:volume of solute =(required concentration/initial concentration )* the total volume of solution . In your case the required concentration is missing , so if we put all the values given in the formula then solve it , we get the required concentration with a value of 6.25% . Please correct me if I'm wrong.
 
Noor Ahmad

Noor Ahmad

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dornam said:
Can you help me with this one? If I have 6.25 cm^3 of 10% solution, and I mix it with 3.75 cm^3 of water, what will be the concentration of the solution?
Click to expand...

C1V1=C2V2
Where the total volume is 6.25+3.75=10
6.25x10 = 10 x C2
C2 = 6.25
 
Noor Ahmad

Noor Ahmad

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Irfan1995 said:
Just draw the three layers. Ignore the details outside the artery. It must be large and proportional (it must be like an oval, not a circle).
The mark scheme provides a good example of a drawing.
Click to expand...


No no i meant the question below that,about the eye piece graticule and the stage micrometer?
 
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