A level Biology: Post your doubts here!

[qwertypoiu]

What about the RNA and DNA questions. RNA form hydrogen bonds between each other, right?

Yeah single RNA strands may form hydrogen bonds within itself like tNRA does.

 

[mohammad tareq]

Hey guys .. Any one have tips for paper 3 biology ... Practicles !! Exam after two days need it fast !! Pls .

 

[mohammad tareq]

No ..its not purkenji tissue..i wrote that too.:/
AVN is made up of muscle tissue.
You thought the asme way i did

... So goys the answer for it was AVN ,... Ok ... Is non-conducting fires correct .. Cus I saw it once in Mcq ...

 

[Midnight dream]

... So goys the answer for it was AVN ,... Ok ... Is non-conducting fires correct .. Cus I saw it once in Mcq ...

-___- already know.:/

 

[alexkay]

paper 4 tips, predictions?

 

[Hassan Mirza Aziz]

Can anyone predict the practical for biology paper 33

 

[saturn21]

Should be right insha Allah I just checked width of cell walls they're measured in nanometers. (Eg 40nm)

Yup InshAllah

 

[qwertypoiu]

Can anyone predict the practical for biology paper 33

Ooooh predictions! I'm amazing at predictions. Here's some predictions I've made:

1. There's gonna be two questions
2. No 1 will be about observing stuff under the microscope
3. no2 will be a "wet" experiment (food test, osmosis, etc.)
4. There will be a part about drawing a simple line/bar graph
5. We'll have to record our results for wet experiment
6. We'll have to make a conclusion in wet experiment
7. We'll have to make a plan diagram in microscope question
8. Oh and you'll also have to do a high power detail diagram of three cells or something
9. You'll also have to label these diagrams

Good luck for exam buddy.

 

[Hassan Mirza Aziz]

Th

Ooooh predictions! I'm amazing at predictions. Here's some predictions I've made:

1. There's gonna be two questions
2. No 1 will be about observing stuff under the microscope
3. no2 will be a "wet" experiment (food test, osmosis, etc.)
4. There will be a part about drawing a simple line/bar graph
5. We'll have to record our results for wet experiment
6. We'll have to make a conclusion in wet experiment
7. We'll have to make a plan diagram in microscope question
8. Oh and you'll also have to do a high power detail diagram of three cells or something
9. You'll also have to label these diagrams

Good luck for exam buddy.

Thank you

 

[Studydayandnight]

Hi guys! I need some help in paper 3.

Firstly, Can some one please tell me how to calibrate the eye piece graticule thing with the stage micrometer?

Also, do they ever ask us to actually calibrate one using a microscope? Or do we just need to know how to do that on paper??

 

[saturn21]

Ooooh predictions! I'm amazing at predictions. Here's some predictions I've made:

1. There's gonna be two questions
2. No 1 will be about observing stuff under the microscope
3. no2 will be a "wet" experiment (food test, osmosis, etc.)
4. There will be a part about drawing a simple line/bar graph
5. We'll have to record our results for wet experiment
6. We'll have to make a conclusion in wet experiment
7. We'll have to make a plan diagram in microscope question
8. Oh and you'll also have to do a high power detail diagram of three cells or something
9. You'll also have to label these diagrams

Good luck for exam buddy.

And what about paper 31?

 

[saturn21]

Can someone help me in serial dilution?? Thanks in advance )
ohh and what's the difference between serial and simple dilution?

 

[My Name]

Can someone help me in serial dilution?? Thanks in advance )
ohh and what's the difference between serial and simple dilution?

Hey I don't exactly have notes for this but I think some videos might help you.

And if you want you can try Paper 3 2011 O/N ( if I remember correctly) it has some part about Serial Dilution.
Btw there is also this formula which you can use (when sometimes in the question they give you some values and you need to CALCULATE some concentration)
C1V1=C2V2
(C=concentration
V=volume)

 

[qwertypoiu]

Hi guys! I need some help in paper 3.

Firstly, Can some one please tell me how to calibrate the eye piece graticule thing with the stage micrometer?

Also, do they ever ask us to actually calibrate one using a microscope? Or do we just need to know how to do that on paper??

I once answered a question about it here. It may help you understand better.
I think we have to know how to measure the size of stuff in diagrams just like in paper 2 sometimes.
As for calibration, I haven't done practically before, (but that's probably because my school never gave us enough practice), but I've read on the syllabus specifically about how they will provide the schools with stage micrometer whereas school should get eyepiece graticule. The skill of calibration is marked with [PA] in the syllabus, it means they may ask you to calibrate.

 

[qwertypoiu]

Can someone help me in serial dilution?? Thanks in advance )
ohh and what's the difference between serial and simple dilution?

I found an excellent site here.
Look at the first two only, the rest are not required.

 

[qwertypoiu]

And what about paper 31?

My "predictions" are so good they apply to all paper 3 variants.

 

[bobbydylan]

For large plan diagrams, do we draw the cells or only the layers?

 

[Mahnoorfatima]

For large plan diagrams, do we draw the cells or only the layers?

Plan is always layers. When they ask you to draw 2 or 3 cells, forexample, then u draw it on high power and obviously the individual cells.

 

[qwertypoiu]

For large plan diagrams, do we draw the cells or only the layers?

The first question is usually about drawing a PLAN DIAGRAM. In this you draw with little magnification, and you only outline tissues. You DONT draw the individual cells.
And then they'll say something like draw three cells touching each other. THEN you draw the individual cells, with highest magnification.

 

[Mahnoorfatima]

I don't get how are we supposed to calculate the percentage concentrations, like forexample we have to do simple dilution and in the first thing we take 20cm^3 of sucrose solution and 0cm3 of H2O and at the beginning it';s mentioned that the sucrose provided is 4 % so we'll say this 20cm3 is 4% right?
But when we, say, take 10cm3 of sucrose and 10cm3 of h2o what wll be the %age conc? Is there is a specific formula for doing so? Our teacher once told us but I forgot. :/