OCR 2010 A2 Biology Unit 2 - Control, Genome and Environment

hi, i was wondering does anyone know of an official AQA chemistry thread for the unit 5 exam this year? cant seem to find it....

Reply 1741

dopeyangel101

HELPME-ology

Does anyone have good material or revision notes they used for the Immune system and disease etc?

thats for the Biology OCR June AS exam.. pleaseeeeeee help me!!!!!!!!

the people who re-sat this paper in Jan 2010 said it was mainly all Biochemistry.. so i have a feeling all the immune system and disease is to definitely come up..

might have some on my school VLE, pm me your email, will lookee-see and if so will email any- and everything i find :smile:

Reply 1742

tara592

Hey can anyone help me on the control of body plan development??
Im a bit confused - are homeobox genes and homeotic genes the same? I have two textbooks that call them different things but seem to have the same function...
Homeotic genes code for the proteins needed to control body plan development. The homeotic genes have regions called homeobox sequences that code for the homeodomain (which is part of the protein). The homeodomain binds to specific sites on the DNA which allows the protein to work as a transcription factor, which are located at the start of developmental genes, activating or repressing transcription which alters the production of proteins involved in the development of body plans.
is that right at all??
also Im not sure where hox clusters fit into it all - all I know is that the homeobox genes (are these homeotic genes??) are arranged in hox clusters...
thanks!

Reply 1743

smflesh

2

Liverpool F.C.™

Here

Thank you!!

Reply 1744

ViolinGirl

9

Sakujo

describe how the distribution and abundance of organisms can be measured, using line transects, belt transects, quadrats and point quadrats (HSW3);

I'd rep if someone does this.

Ok, you can take samples within a habitat in order to determine the abundance/distirbution of a particular species, and then you see if this is determined by other species or environmental factors such as light or nitrates in the soil. e.g. There may type of one plant growing in the light, but lots more of another species in the shade.

Ideally, it would be best to count all the individuals in the habitat, but this is not possible so samples are taken. There are various methods of taking samples:

1) Quadrats- these are square frames 1m by 1m that define the sample space, they have string inside the frame separating the square into 100 smaller squares. You can either find out the distribution of a species by counting the presence/absence of them in the quadrat or you can estimate the abundance by taking a percentage cover estimate.

You can do this just with a quadrat but taking a % coverage is more acurate using a point frame/quadrat.

You point the frame into the ground within the quadrat, and record the species that are touching each of the pins, this is representive of the cover.
There are 10 pins on each frame and this can be repeated 10 times in a quadrat.

2) Transects- these are lines taken across a habitat and you record the samples along the line at regular intervals.
You can use this in association with a quadrat, whereby you place a quadrat by the line at intervals and use that to measure abundance/percentage cover. This is called a belt transect.

Reply 1745

uer23

15

dopeyangel101

might have some on my school VLE, pm me your email, will lookee-see and if so will email any- and everything i find :smile:

anything yet about the genetics questions ? done the rest, just waiting for genetics now.

Reply 1746

dopeyangel101

i'll see what i can do tomorrow, shall attempt to use my scanner at home, if not will take photos of each page then upload them. sorry i havent done it yet, have honestly been too busy revising for chemistry....

Reply 1747

Sakujo

14

Genetics pack mark scheme.doc

Genetics pack-1.doc

Genetics questions and mark schemes for those who want it, uer23. :smile:

EDIT: Fixed

Reply 1748

dopeyangel101

Sakujo

Attachment not found

Genetics pack mark scheme.doc

Genetics questions and mark schemes for those who want it, uer23. :smile:

the actual questions dont work on my computer, comes up with a load of random numbers and letters...

Reply 1749

Liverpool F.C.™

11

Sakujo

Attachment not found

Genetics pack mark scheme.doc

Genetics questions and mark schemes for those who want it, uer23. :smile:

Hey brother thanks a lot :smile:

Do you more of these question packs, like the ones you did for chem ?

Reply 1750

Sakujo

14

dopeyangel101

the actual questions dont work on my computer, comes up with a load of random numbers and letters...

Should be fixed for some reason the document was in rtf format not doc

Reply 1751

Sakujo

14

Liverpool F.C.&#8482

Hey brother thanks a lot :smile:

Do you more of these question packs, like the ones you did for chem ?

My humble apologies bro but I don't, I really wished I did though. :sigh:

Reply 1752

dopeyangel101

Sakujo

Should be fixed for some reason the document was in rtf format not doc

thanks, tis sorted now :smile:

saved me a lot of hassle too :smile:

Reply 1753

zoop

Thank ViolinGirl.

Right, what does niche mean in this sentence?

'The more niches overlap, the more likely competition will occur.'

Reply 1754

ViolinGirl

9

zoop

Thank ViolinGirl.

Right, what does niche mean in this sentence?

'The more niches overlap, the more likely competition will occur.'

No problem. Please ask away :smile:

Well, the niche is the role an organism plays in its ecosystem, this can include what it feeds on, what it excretes, how it reproduces.

Some niches of different species can be similar, but they are never identical, as it just isn't possible.

So the more similar the niches are, it means that the organisms are more likely to comptete with one another, as for example they may share the same food sources, so will have to comptete over this. One species may be better adapted at harvesting that food source, they will be the species that thrives while the other one has more of a struggle to survive.

Reply 1755

zoop

ViolinGirl

No problem. Please ask away :smile:

Well, the niche is the role an organism plays in its ecosystem, this can include what it feeds on, what it excretes, how it reproduces.

Some niches of different species can be similar, but they are never identical, as it just isn't possible.

So the more similar the niches are, it means that the organisms are more likely to comptete with one another, as for example they may share the same food sources, so will have to comptete over this. One species may be better adapted at harvesting that food source, they will be the species that thrives while the other one has more of a struggle to survive.

Aha my typing is appalling!! Thanks again, completely get it now. Man u'll ace this easily! How do u revise if u don't write any notes? U seem to know it all real well! U're off for vet med too aren't u? Where are ya going?

Would + rep you but can't for another 28 days app :o:

Reply 1756

dopeyangel101

ViolinGirl

No problem. Please ask away :smile:

Well, the niche is the role an organism plays in its ecosystem, this can include what it feeds on, what it excretes, how it reproduces.

Some niches of different species can be similar, but they are never identical, as it just isn't possible.

So the more similar the niches are, it means that the organisms are more likely to comptete with one another, as for example they may share the same food sources, so will have to comptete over this. One species may be better adapted at harvesting that food source, they will be the species that thrives while the other one has more of a struggle to survive.