Edexcel A2 Biology Unit 4(6BIO4) 13/06/11 - OFFICIAL THREAD !

What is the brine shrimp practical? I have no idea :s-smilie:

can anyone tell me it step by step? and the one about temperature on organisms?

This is the one abt the Effect Of Temperature on organisms!

Chill it's prolly nt gna come .. But yea just chk out the notes sm1n posted earlier ... it's got the whole process in Detail! xD

Reply 321

bashx

you know for our specification, is it justthe january 2010 paper that is the latest?
im confused
can we use the janu 09 papers?

Reply 322

darkiee

10

Original post by LibbyU

What is the brine shrimp practical? I have no idea :s-smilie:

can anyone tell me it step by step? and the one about temperature on organisms?

Decide on the range of temperatures to be tested
• Place a tiny pinch of egg cysts onto a large sheet of white paper
• Wet the piece of graph paper using a few drops of salt water. Dab the paper onto the white
sheet to pick up approximately 40 eggs
• Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of
forceps to gently remove the paper, making sure that all the egg cysts have washed off into the
water
• Repeat for all the temperatures that are to be investigated
• Incubate the beakers at the appropriate temperatures, controlling exposure to light as far as
possible
• The next day count the number of hatched larvae in each of the beakers. Do this for several days
• Record the number of larvae that have successfully hatched at each temperature

Reply 323

Samia99

Original post by darkiee

Decide on the range of temperatures to be tested
• Place a tiny pinch of egg cysts onto a large sheet of white paper
• Wet the piece of graph paper using a few drops of salt water. Dab the paper onto the white
sheet to pick up approximately 40 eggs
• Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of
forceps to gently remove the paper, making sure that all the egg cysts have washed off into the
water
• Repeat for all the temperatures that are to be investigated
• Incubate the beakers at the appropriate temperatures, controlling exposure to light as far as
possible
• The next day count the number of hatched larvae in each of the beakers. Do this for several days
• Record the number of larvae that have successfully hatched at each temperature

Yea this is it!
And we had to write this entire procedure for 6BIO8 ppr!

Reply 324

bashx

where are the jnaury 09 and une 09 past papers?

Reply 325

darkiee

10

Original post by bashx

where are the jnaury 09 and une 09 past papers?

There is none, this is a new syllabus that started 2008, so do the maths the 1st A2 for the new syllabus will be 2010

Reply 326

Samia99

Original post by bashx

where are the jnaury 09 and une 09 past papers?

The first ppr of the new spec was Assessd in Jan 1O.

Though yu can get old spec ppr too!
Google it! or try xtremepapers.net :rolleyes:

Reply 327

InItToWinItGetIt?

11

Original post by Samia99

Umm yeah! That was Dna profiling!
PCR's still didn't :tongue:

Evn though Dna's amplifyd thru it and used in the gel electrophoresis to create a Profyl ... Relatd :tongue:

Ahan, let's just focus on PCR & Gel Elctrophoresis , Ecology too!

Brine Shrimps came up this year! for 6BIO8!
They nevr give the same practical for 6BIO8 & 6BIO4!

Although there's no harm in revising :tongue:

how do you know?

Reply 328

bashx

thank you. i just wanted to see any past paper questions.
how you feeling about the exam?

Reply 329

Samia99

Original post by InItToWinItGetIt?

how do you know?

lool They nevr pop up da same practical Q!
Lyk me all int'l Candidates gave 6bio8 ..nd many r giving unit 4 & 5 too ...
So the Xaminer's dnt really give the same Q for both the papers .. they'll try a diffrnt practical ...

But,just to b on da safe syd it wldn't hurt to go thru the practical once :tongue:

Reply 330

InItToWinItGetIt?

11

What's clonal selection in reference to lymphocytes?

Reply 331

InItToWinItGetIt?

11

Original post by Samia99

lool They nevr pop up da same practical Q!
Lyk me all int'l Candidates gave 6bio8 ..nd many r giving unit 4 & 5 too ...
So the Xaminer's dnt really give the same Q for both the papers .. they'll try a diffrnt practical ...

But,just to b on da safe syd it wldn't hurt to go thru the practical once :tongue:

if that's the case, then gel electrophoresis or PCR is probably coming up. I don't think they've asked either of them.

Reply 332

LibbyU

Original post by darkiee

Decide on the range of temperatures to be tested
• Place a tiny pinch of egg cysts onto a large sheet of white paper
• Wet the piece of graph paper using a few drops of salt water. Dab the paper onto the white
sheet to pick up approximately 40 eggs
• Put the paper with the 40 eggs into the beaker (eggs-side down). After 3 minutes, use a pair of
forceps to gently remove the paper, making sure that all the egg cysts have washed off into the
water
• Repeat for all the temperatures that are to be investigated
• Incubate the beakers at the appropriate temperatures, controlling exposure to light as far as
possible
• The next day count the number of hatched larvae in each of the beakers. Do this for several days
• Record the number of larvae that have successfully hatched at each temperature

thank you! :smile:

so the brine shrimp practical and the effect on temperature is the same practical?

Reply 333

LibbyU

Is unit 4 a synpotic paper? I know in the last one it asked some things from AS like structure of cellulose, but I thought it was only unit 5 that was synoptic? and apart from that one AS question the rest seemed to be just unit 4?

Ahh well, the good thing about being a failure and having to resit all your AS and A2 exams means you're pretty clued up for synoptic stuff I guess :P

Reply 334

idiotone

How does HIV stimulate the immune system to produce antibody molecules?

The mark scheme says that antibody on B-lymphocytes bind to antigens acting as lables allowing phagocytes to recognise and destroy the cell..

Whats confusing is does phagocyte need a APC to be activated? and how comes B cell comes first than T cell?

Reply 335

LibbyU

Does anyone else have other exams tomorrow as well as this one or is it just me? Ive got an exam at 9am then this one at 1.30pm :frown:

FML

Reply 336

darkiee

10

Original post by idiotone

How does HIV stimulate the immune system to produce antibody molecules?

The mark scheme says that antibody on B-lymphocytes bind to antigens acting as lables allowing phagocytes to recognise and destroy the cell..

Whats confusing is does phagocyte need a APC to be activated? and how comes B cell comes first than T cell?

WTF, i confidently said it doesnt to myself, I swear HIV bind tto t-helper cells and replicates.....

It doesnt stimulate it to produce antibody molecules :s-smilie:

am confused

Reply 337

InItToWinItGetIt?

11

Original post by idiotone

How does HIV stimulate the immune system to produce antibody molecules?

The mark scheme says that antibody on B-lymphocytes bind to antigens acting as lables allowing phagocytes to recognise and destroy the cell..

Whats confusing is does phagocyte need a APC to be activated? and how comes B cell comes first than T cell?

I have that question:

the MS is just asking what is the B-cell response.

- recognition of foreign antigen
- b cell proliferation (divides by mitosis)
- to produce plasma cells and memory cells
- plasma cells produce specific antibodies
- clonal selection

Original post by darkiee

WTF, i confidently said it doesnt to myself, I swear HIV bind tto t-helper cells and replicates.....

It doesnt stimulate it to produce antibody molecules :s-smilie:

am confused

HIV does infect t-helper cells, but remember there are probably BILLIONS of t-helper cells in your blood. Not all of them will be infected.

It does produce antibodies. EVERY foreign antigen leads to a production of antibodies.

HIV +ve people are identified as HIV +ve by looking for presence of HIV antibodies in their blood.

Reply 338

doobucks

16

Original post by Samia99

Umm yeah! That was Dna profiling!
PCR's still didn't :tongue:

Evn though Dna's amplifyd thru it and used in the gel electrophoresis to create a Profyl ... Relatd :tongue:

Ahan, let's just focus on PCR & Gel Elctrophoresis , Ecology too!

Brine Shrimps came up this year! for 6BIO8!
They nevr give the same practical for 6BIO8 & 6BIO4!

Although there's no harm in revising :tongue:

Likelyhood will be PCR then. Also I think there'll be a time of death question as there was no time of death question last time, maybe an explanation of rigor mortis?

Reply 339

nackai

ma gooods im feeling so confused about this exam.... ive got the jan 2011 one and the jan 2010 one.... definately going to be something on DNA profiling and mabey on ecology... but there was alot of stuff on ecology in jan 2011.

I DONT KNOW WHAT TO FOCUS ON..... IM FREAKIN BALLS :P :P :P

Edexcel A2 Biology Unit 4(6BIO4) 13/06/11 - OFFICIAL THREAD !

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